PLoS One. 2016; 11(8): e0160037.
Published online 2016 Aug 3. doi: 10.1371/journal.pone.0160037
PMCID: PMC4972425
Tim Friede, Editor
Abstract
Background Context
Low
back pain (LBP) is one of the leading causes of disability worldwide
and among the most common reasons for seeking primary sector care.
Chiropractors, physical therapists and general practitioners are among
those providers that treat LBP patients, but there is only limited
evidence regarding the effectiveness and economic evaluation of care
offered by these provider groups.
Purpose
To
estimate the clinical effectiveness and to systematically review the
literature of full economic evaluation of chiropractic care compared to
other commonly used care approaches among adult patients with
non-specific LBP.
Study Design
Systematic reviews of interventions and economic evaluations.
Methods
A
comprehensive search strategy was conducted to identify 1) pragmatic
randomized controlled trials (RCTs) and/or 2) full economic evaluations
of chiropractic care for low back pain compared to standard care
delivered by other healthcare providers. Studies published between 1990
and 4th June 2015 were considered. Primary outcomes included
pain, functional status and global improvement. Study selection,
critical quality appraisal and data extraction were conducted by two
independent reviewers. Data from RCTs with low risk of bias were
included in a meta-analysis to determine effect estimates. Cost
estimates of full economic evaluations were converted to 2015 USD and
results summarized using Slavin’s qualitative best-evidence synthesis.
Results
Six
RCTs and three full economic evaluations were scientifically
admissible. Five RCTs with low risk of bias compared chiropractic care
to exercise therapy (n = 1), physical therapy (n = 3) and medical care
(n = 1). Overall, we found similar effects for chiropractic care and the
other types of care and no reports of serious adverse events. Three low
to high quality full economic evaluations studies (one
cost-effectiveness, one cost-minimization and one cost-benefit) compared
chiropractic to medical care. Given the divergent conclusions (favours
chiropractic, favours medical care, equivalent options), mixed-evidence
was found for economic evaluations of chiropractic care compared to
medical care.
Conclusion
Moderate
evidence suggests that chiropractic care for LBP appears to be equally
effective as physical therapy. Limited evidence suggests the same
conclusion when chiropractic care is compared to exercise therapy and
medical care although no firm conclusion can be reached at this time. No
serious adverse events were reported for any type of care. Our review
was also unable to clarify whether chiropractic or medical care is more
cost-effective. Given the limited available evidence, the decision to
seek or to refer patients for chiropractic care should be based on
patient preference and values. Future studies are likely to have an
important impact on our estimates as these were based on only a few
admissible studies.
Background
Low back pain (LBP) is the most common occupational disorder in North America [1, 2], a major cause of work absenteeism [3, 4] and a leading cause of disability worldwide [5].
The 2010 Global Burden of Disease Study revealed that the LBP
disability-adjusted life years increased from 58.2 million in 1990 to
83.0 million in 2010[6], although the majority of LBP patients experience non-specific symptoms that cannot be attributed to a serious disease [7].The global point prevalence of LBP is 9.4% [6] and the life time prevalence is around 85% [8, 9].
A
number of factors drive patients’ choice for a specific health
provider. First, access to professionals is influenced by a traditional
medical model of referral [10]. Other structural factors include the regional supply of providers [11, 12] or coverage of provider services in medical insurance schemes [13].
Financial reasons (such as out of pocket expenses), socio-cultural
(such as traditions) and personal beliefs and preferences are also
driving factors [14]. Perhaps as a result, patients with LBP tend to first consult general physicians [10]. However, an increasing number of LBP sufferers seek care directly from other healthcare professionals [15, 16]. From 2006 to 2010, the proportion of patients self-referring to physiotherapists in The Netherlands rose from 22% to 43%[17]. LBP patients also commonly seek chiropractic care [18–20]. At least one third of back pain patients in Denmark choose to see a chiropractor as their entry into the healthcare system [15].
North
American health technology assessments on chiropractic care conducted
over a decade ago were unable to provide clear guidance to inform
decision-making on the effectiveness and cost effectiveness of
chiropractic care compared to medical and physiotherapy care [21, 22].
This was primarily because their analysis was based on a limited number
of studies of acceptable methodological quality and partial economic
evaluations (cost description, cost analysis and cost-outcome
description) [21, 22].
In
a fastidious trial, the efficacy of spinal manipulative therapy (SMT)
is tested under optimal conditions in order to isolate its effect from
the confounding factors [23].
While in a pragmatic trial, the effectiveness of chiropractic care is
tested in close to ‘real-world’ clinical settings to measure the degree
of beneficial effect under this type of conditions [23].
More recently, systematic reviews on the effectiveness of SMT combined
the two types of studies and concluded that this approach was as
effective as other commonly used treatment modalities [24–26]. While SMT is an important component of chiropractic care [27], these providers commonly use multimodal care to treat their patients with LBP in order to enhance treatment outcome [28] [29]. SMT is also performed by a range of other healthcare professionals [25, 26].
Thus, studies evaluating the effectiveness of SMT can guide clinicians
in the choice of treatment modality, but provide little guidance to
patients regarding which healthcare provider they should seek care from.
When
referring to other providers, inter-professional relations appear to be
important to clinicians, where cost is likely a major driver for third
party payers when deciding to include a type of provider within a
healthcare plan [30–32].
However, healthcare providers, policy makers and third party payers
should likely consider the clinical effectiveness, the
cost-effectiveness, the safety of the approach, and patient preference
and values when referring (LBP) patients for a specific type of care or
including a service in a medical insurance scheme, [24, 25, 33].
Full economic evaluation (cost-effectiveness analysis, cost-utility
analysis, cost-benefit analysis) of standard care practice offers the
advantage of simultaneously considering the resources involved (costs)
and the health outcomes (outputs) [34]. This is important when formulating recommendations on the optimal use of healthcare resources [35].
This review therefore aimed to synthetize recent high quality evidence
to better inform patients, clinicians, policy makers, and third party
payers about the clinical effectiveness and cost-effectiveness of
standard chiropractic care for LBP in comparison to usual standard care
provided by other healthcare providers. The specific objectives of this
review were: 1) to estimate the extent to which chiropractic care is
effective for adult patients with non-specific low back pain compared to
other conservative care approaches (e.g. medical care and
physiotherapy), and 2) to systematically review the literature of full
economic evaluation of chiropractic care for adult patients with
non-specific LBP compared with other conservative care approaches
conducted from any perspective.
Materials and Methods
Eligibility criteria
We conducted two systematic reviews: 1) a review of clinical effectiveness and 2) an economic review.
Study characteristics
For
the clinical effectiveness review, only randomised controlled trials
were eligible for inclusion. For the economic review, studies with a
full economic evaluation (i.e. cost-effectiveness, cost-utility,
cost-benefit analyses and cost-minimization analysis alongside a
clinical trial [36]) were eligible.
Population under study
Adult
patients (≥ 18 years) with non-specific LBP with or without sciatica of
any duration were eligible for inclusion. We excluded studies reporting
on spinal pain without separate results for LBP and studies examining
specific pathologies (e.g., disc herniation or compression fractures).
Types of interventions
We
compared pragmatic trials of chiropractic standard care with standard
care delivered by other healthcare providers. Chiropractic standard care
was defined as patient-centred, multimodal care (e.g. combinations of
SMT, soft tissue techniques, prescription of exercise, advice and
reassurance) planned and delivered by a licensed chiropractor. We
excluded studies investigating chiropractic care combined with care
delivered by other healthcare providers, studies investigating a
specific treatment modality or technique, and trials aiming to isolate
the effect of SMT (i.e. fastidious trials). The lead authors of
potentially relevant studies were contacted for further clarity
regarding type of care.
The
comparators were conservative, standard care for LBP delivered by other
healthcare providers (e.g. medical doctor, physical therapist, exercise
therapist or acupuncturist). Studies were judged eligible if the
original author, when contacted for clarification, considered the
comparator group as standard care. Study arms including surgical
treatment or multidisciplinary care were excluded.
Types of outcome measures
- For the clinical effectiveness review:
Primary outcomes:
- Pain (e.g., visual analogue scale, numerical rating scale, McGill pain score)
- Functional status (e.g. Roland-Morris questionnaire, Oswestry Disability Index)
- Global improvement (e.g., the proportion of patients recovered)
Secondary outcomes:
- Health related quality of life (e.g., SF-36, EuroQol)
- Return to work (e.g. number of days to return to work or proportion of patients at work)
- Adverse events
-
For the economic review: an incremental measure of the extra cost
required to improve an additional unit of outcome (e.g., an incremental
cost-effectiveness ratio (ICER) or an incremental net benefit measure)
with the exception of cost-minimization studies for which only costs
were considered.
Additional criteria
Studies
published in languages other than English or French, duplicate
publications and studies without full text manuscript available (e.g.
abstracts, conference proceedings, presentations) were excluded.
Information sources
Electronic searches
We
developed our search strategies with an experienced health sciences
librarian (JB) (The complete search strategies can be found in the
published protocol[37]).
A second librarian (PH) reviewed the search strategy for completeness
and accuracy. We searched the following databases: Ovid Medline, Ovid
AMED, Ovid EMBASE, CINAHL, the Cochrane Database of Systematic Reviews,
and PubMed. We further searched for economic evaluations in four
additional databases: Index to Chiropractic Literature (ICL); Cochrane
Library; Health Technology Assessment Database; and ECONLIT. We searched
all bibliographic databases from 1990 to 7th June 2016.
The
search strategies (clinical effectiveness and economic evaluation) were
first developed in MEDLINE and subsequently adapted to the other
bibliographic databases. The search terms included subject headings (eg,
MeSH) specific to each database and free-text words relevant to low
back pain. We used Endnote (version X7.3.1, Thomson Reuters,
Philadelphia, PA, USA) to create a bibliographic database to manage the
search results.
Other resources
We
screened reference lists of relevant publications, including reviews
and meta-analyses, for relevant articles, and reviewed the gray
literature available from the following websites: Canadian Institute for
Health Information (CIHI); Canadian Agency for Drugs and Technologies
in Health (CADTH); Canadian Institute of Health Research (CIHR); Tufts
Medical Center Cost-effectiveness Analysis Registry; Agency for
Healthcare Research and Quality; National Institute for Health Research
Health Technology Assessment program; and National Institute for Health
and Care Excellence (NICE).
Study selection
Two
pairs of authors independently screened titles, abstracts, and full
text papers for the clinical effectiveness (MAB and MJS) and for the
economic evaluation reviews (MAB and AB). A third reviewer (MJS) was
included in the full text screening of the economic evaluations.
Reviewers met to resolve disagreements and reach consensus on the
eligibility of studies.
Quality assessment
Clinical effectiveness studies
Two
reviewers with expertise related to chiropractic care and clinical
trials (MAB and MJS) critically appraised the internal validity of
included studies using the 13 criteria recommended by the Cochrane Back
Review Group [38].
Studies that met at least 6 criteria out of 13 were considered low risk
of bias. Items related to the blinding of patients, care providers, and
outcome assessors (patient reported outcomes) were reported in the risk
of bias assessment, but cannot be fulfilled when studying the outcome
of different groups of healthcare providers.
Economic evaluations
The
methodological quality of the economic evaluation was independently
assessed by two reviewers using the Drummond BMJ Check list [39–41]:
one with expertise related to chiropractic care and epidemiology (MAB)
and one with expertise related to healthcare administration and health
economics (RBDS). The checklist included 35 items related to study
design; data collection; data analysis; and interpretation of results.
Additionally, the reviewers formulated a qualitative appreciation of the
quality level (low, medium, high) of every study:
High quality:
The majority of the quality assessment criteria are met. There is
little or no methodological flaw that might influence the study
conclusion.
Medium quality: Most of the quality assessment criteria are met. Some flaws in the study may influence the study conclusion.
Low quality:
Either most of the quality assessment criteria are not met, or
significant flaws relating to key aspects of study are likely to
influence the study conclusion.
Data extraction
Data
extraction was performed by the lead investigator (MAB) and checked for
accuracy against the original publication by a second reviewer for the
clinical effectiveness trial (MJS) and the economic evaluation (RBDS).
The standard form developed by the Cochrane back review group [42]
was used to extract descriptive and outcome data from the clinical
effectiveness studies. Authors of studies only reporting between group
differences [43–46]
were unsuccessfully contacted in order to obtain mean and standard
deviation of primary outcomes at relevant time points. Therefore, the
means were inferred from graphical representations and our analysis were
based on the reported between group differences. Data extracted from
studies at high risk of bias were not reported.
A customized data extraction form [37]
was used for the economic evaluations. Authors of the economic
evaluations were contacted in order to gain precision about the
perspective of analysis and the type of care considered.
Data analysis
Clinical effectiveness studies
Primary
and secondary outcomes of studies with low risk of bias were evaluated
in meta-analyses. Final scores of reported outcomes were used for the
meta-analyses. Data were estimated, using the Review Manager calculator
(RevMan version 5.3, The Cochrane Collaboration, Copenhagen, Denmark)
when change scores and between group differences were reported. Outcomes
were assessed at 1, 3, and 12 months. In order to minimize clinical
diversity, we stratified by: healthcare provider (chiropractic care
versus medical care, physical therapy and exercise therapy), symptom
duration (sub-acute/chronic (6 weeks or more) and mix/not specified),
and outcomes (type of outcome and time of assessment). To facilitate
comparison between different instruments, comparisons were made using
standardized mean difference for continuous outcomes and a risk ratio
for dichotomous outcomes. Due to substantial heterogeneity, we used a
random effect model. Heterogeneity was investigated by subjective
interpretation and by statistical testing using the Q (Chi2), Tau2 and I2 test. We, a priori, determined a cut-off of 40% at the I2
test for reporting pooled estimates. However, due to the limited number
of studies, we decided to present the pooled results along with
potential sources of heterogeneity even if this criterion was not met.
Sensitivity analysis by adding studies with high risk of bias and
construction of funnel plots to evaluate possible publication bias were
planned [37],
but not conducted because the high risk of bias study retrieved only
reported results graphically and the number of studies retrieves was too
low to construct a meaningful funnel plot. All meta-analyses
calculations and related metrics were conducted in Review Manager for
Mac OS X (RevMan version 5.3, The Cochrane Collaboration, Copenhagen,
Denmark).
Economic evaluations
In
order to compare costs across different currencies and account for
differential timing, costs of the original study were converted to 2015
United-States (US) dollar using a web-based tool based on purchasing
power parities (PPP) and gross domestic product deflators (GDPD) values
from the World Economic Outlook Database [47].
The level of evidence of the economic findings was assessed using a
5-point ordinal scale defined by Slavin’s qualitative best-evidence
synthesis approach [48]. The following criteria were assessed in stepwise descending manner:
Strong Evidence: minimum of 3 high quality studies; at least three-quarters of high and medium quality studies must concur on findings.
Moderate Evidence:
minimum of 2 high quality studies, or 3 of medium and high quality;
more than two thirds of all studies must report consistent findings.
Limited Evidence: minimum of 1 high quality study or 2 medium quality studies, more than 50% of all studies must report consistent findings.
Mixed Evidence: findings from medium and high quality studies are contradictory.
Insufficient/No Evidence: no high quality studies; one or no medium quality studies; any number of low quality studies.
Reporting
The
systematic review was organized and reported based on the Preferred
Reporting Items for Systematic Reviews and Meta-Analyses statement[49].
Systematic review registration
The
protocol was registered with the International Prospective Register of
Systematic Reviews on October 20, 2014 (CRD42014008746) at: http://www.crd.york.ac.uk/PROSPERO.
FDA device/drug status: Not applicable.
Results
Clinical effectiveness
Study selection
Our search retrieved 4,095 articles. We removed 1,764 duplicates and screened 2,331 articles for eligibility (Fig 1).
After screening, 2,281 articles did not meet our selection criteria,
whereas 50 citations were assessed for eligibility in full-text. Eight
citations [43–46, 50–53] originating from six individual studies were included in the review (Fig 1).
The main reasons for exclusion after full test screening were: care not
provided by a chiropractor or investigation of a specific treatment
modality. One potentially relevant study with no results available was
identified on clinicaltrials.gov (NCT01357343).
Flow diagram for the selection of clinical effectiveness studies.
Study characteristics
Characteristics of the included studies are presented in Table 1. One Canadian study [52]
comparing chiropractic care to physical therapy care had a high risk of
bias; therefore we did not include its results into our quantitative
analysis and did not further report study findings. The remaining five
low risk of bias studies were published between 1990 and 2011 and were
conducted in the US (n = 3) [45, 46, 50–52], United Kingdom (UK, n = 1) [43, 44], and Denmark (n = 1) [53]. Chiropractic care was compared to exercise therapy care in one study [50], to physical therapy care in four studies [43, 44, 51, 53] and to medical care in one study[45, 46].
Cohort sizes varied from 155–741 participants and follow-up periods
varied from one to three years. We obtained effect estimates for all our
primary and secondary outcomes with the exception of return to work.
Only the two most recent studies reported responder analysis [50, 53].
Characteristics
of the clinical effectiveness studies included into the quantitative
synthesis of Chiropractic care for non-specific low back pain.
Risk of bias within studies
The methodological quality of the scientifically admissible studies is presented in Table 2.
Most studies (5/6) had a low risk of bias with the exception of one
which had a high or unclear risk of bias for the majority of the
evaluated item (12/13) [52]. Among the low risk of bias studies, one publication provided an unclear description of the randomization [51] and another one did the same for the allocation concealment [43, 44].
As expected items related to the blinding of patients, care providers,
and outcome assessors were at high risk of bias in every study due to
the intervention and outcome considered in this review. Selective
outcome reporting was suspected in one study reporting an unusual
primary outcome [53]. Co-interventions use was different between groups in one study [45, 46] and unclear in another one [43, 44]. Compliance was different between the two treatments group in one study [53] and could not be clearly evaluated in two studies [43, 44, 51].
The possibility of an additional bias was suspected in one study that
restricted the number of treatment sessions in only one of its treatment
groups [43, 44].
Risk of bias of the included clinical effectiveness studies of chiropractic care for non-specific low back pain.
Summary of evidence
Chiropractic care vs exercise therapy care
Bronfort et al. [50]
compared chiropractic care to exercise therapy in the United States for
LBP subjects of at least six weeks duration. The extracted results are
presented in Table 3.
Outcomes of pain, functional status and global improvement assessed at
one, three and 12 months revealed no significant difference between the
two provider groups. The responder analysis (proportion of patients with
at least 50% and 75% improvement) was coherent with the averaged
results and no significant difference was found between the two types of
provider for pain, functional status and global improvement assessed at
three and 12 months.
Chiropractic care versus Exercise therapist care.
Health
related quality of life was assessed at one, three and 12 months using
the physical and mental health subscales of the SF-36. The only
statistically significant difference favour chiropractic care for the
mental subscale at three months follow-up.
The rate of adverse effects did not differ significantly between the two treatment groups (Table 4).
These were rare (2% and 6% for chiropractic and exercise therapy care
respectively), transient in nature, and necessitated minimal or no
change in activity level.
Adverse events.
Chiropractic care vs physical therapy care
Three studies compared chiropractic to physical therapy care; they were conducted in the United-States [51], United Kingdom [43, 44] and Denmark [53]. Two included a mix of LBP duration [43, 44, 51] and one included subjects with symptom onset of six weeks or more [53]. The extracted results and pooled effect are presented in Table 5 and Fig 2.
Forest plots of comparison: Chiropractic care versus Physical therapy care.
Chiropractic care versus Physical therapy care.
Pain
was assessed at three and 12 months by only one study. There was no
significant difference between the two treatment groups.
Functional
status was assessed at 1 month (n = 2), 3 months (n = 2) and 12 months
(n = 2). None of the individual studies or the pooled effects showed
significant between group differences. The only exception was the Danish
study [53],
in which a small statistically significant effect in favour of physical
therapy care at the 12 months follow-up was reported. The responder
analysis (number of patients with an absolute Roland Morris score below 5
points or at least 5 points reduction) of that study revealed no
significant between group difference for functional status at three and
12 months. This study was the only one to report functional status at 12
months for subacute/chronic subpopulation. Nevertheless, the pooled
effect, including results of the Meade study [43, 44]
from a mixed subpopulation, did not reveal significant between group
differences. The heterogeneity analysis of the pooled three and 12
months outcomes showed substantial heterogeneity. Potential sources
were: different settings (USA, UK and Denmark), different subpopulations
in terms of symptom duration, and different physical therapy approaches
(McKenzie method) and usual hospital outpatient clinic.
Global improvement was assessed at one and three months in one study. At one month, Meade et al. [43, 44] reported a statistically significant advantage in favour of chiropractic care, while at three months Petersen et al. [53] reported a statistically significant advantage in favour of physical therapy care.
Health related quality of life was only reported by Petersen et al. [53]
at three and 12 months using the general health perception and mental
health subscales of the SF-36. None of the comparisons significantly
statistically favoured one type of care.
Return to work was also reported in the Danish study [53].
Since the two treatment groups were significantly different regarding
their number of participants off work at baseline, we chose not to
extract data for that particular outcome.
Chiropractic care vs medical care
Only
one study compared chiropractic care to medical care. The study was
conducted by Hurwitz et al. in the United States and included subjects
with a mixed symptom duration of LBP [45, 46]. Extracted results for this study are presented into Table 6.
Chiropractic care versus Medical care.
Pain
and functional status were assessed at one and 12 months. There was no
significant difference between the two treatment groups.
Global
improvement, health related quality of life, and return to work were
not assessed. No serious adverse events were recorded in neither of the
treatment group (Table 4).
Overall,
the pooled results did not show significant differences in
effectiveness between chiropractic care and the other type of standard
care studied. When reported, no serious adverse events were recorded in
any of the chiropractic, exercise therapy [50], physical therapy [51] or medical [45, 46] treatment groups (Table 4).
Economic evaluation
Study selection
Our search yielded 2,725 citations. We removed 905 duplicates and screened 1,820 articles for eligibility (Fig 3).
After screening, 1,761 articles did not meet our selection criteria.
Fifty-nine articles were assessed for eligibility and only three
articles were scientifically admissible. The main reasons for exclusion
of the full papers were: partial economic evaluations or lack of any
cost evaluation.
Flow diagram for the selection of economic evaluations.
Study characteristics
The characteristics of these included studies are presented in Table 7.
All three included studies were conducted in the United-States,
included between 417 and 2780 participants, and involved follow-up
periods ranging from 1 to 3.7 years. The types of economic evaluation
performed were: cost-effectiveness analysis (n = 1) [54], cost-benefits analysis (n = 1) [55], and cost-minimizations analysis conducted along with a randomized clinical trial (n = 1) [56].
All three included studies compared chiropractic care to combinations
of medical care. The quality assessment of the included studies is
reported in Table 8.
Characteristics, key findings of economic evaluations of Chiropractic care for non-specific low back pain.
Quality assessment of economic evaluation of chiropractic cares for non-specific low back pain.
Summary of evidence and quality assessment
Butler et al. [55]
conducted a cost-benefit study in the US from the perspective of the
employer as a proxy of the societal perspective. The authors used data
from a prospective cohort study as an exemplar to present a method for
adjusting rehabilitation costs and benefits for health capital. The
cohort consisted of patients with occupational low back pain from five
employers across 37 federal states. Chiropractic care (n = 15 patients)
was compared to different types of providers: medical doctors (n = 20
patients), medical doctors and physical therapists (MDPt, n = 144
patients), chiropractors and medical doctors (n = 105 patients), and
surgeons or emergency physicians (n = 133 patients). Direct costs
(offices visits, consultations, physical medicine, radiographs,
medication) and indirect costs (saving from work loss day) were
considered. Costs related to the household sector were not included.
Based on the nearly identical adjusted net benefits for physician only
care (135,824$), physician plus physical therapy care (130,064$), and
chiropractic care (132,989$), the three types of care seemed equivalent.
Net benefits of care were lower for combined physician/chiropractic
care (104,025$), and lowest for all other forms of care (104,025$).
Precision of the estimates and sensitivity analysis were not reported.
Butler et al. presented the analysis as an exemplar and therefore the
sample size in the chiropractic group was low. With only 15 patients
receiving chiropractic care, the parametric multivariate analyses
conducted by the author is likely underpowered and their conclusions
therefore not robust. Based on this, we rated the study quality as low
despite the high quality of their methodology.
Haas et al. [54]
conducted a cost effectiveness study from the perspective of the
healthcare system (Medicare) based on a prospective cohort study. They
recruited participants from 51 chiropractic clinics (n = 60 providers
and n = 1855 patients) and 14 general practice community clinics (n =
111 medical providers and n = 925 patients) in Oregon and Washington,
US. The effectiveness measures were based on patient- reported outcomes
including pain, functional status, treatment satisfaction, and physical
and mental health. The following direct costs were considered: office
visits, radiographs and medication. The costs related to advance imaging
[57], surgical [58] and physical therapy consultations [51]
were imputed from previous published studies. The services provided
were assigned Current Procedural Terminology (CPT) codes that were
converted to Medicare relative value units, and a conversion factor was
applied to estimate the Medicare payment. The adjusted mean differences
(AMDs) of total cost at 12 months revealed that chiropractic care was
slightly more expensive than medical care for acute (63$, P = 0.352) and
chronic patients (1.5$, p = 0.993), but the differences were not
significant. The AMDs for pain and functional status at 12 months
significantly advantaged chiropractic care, but were not clinically
important (AMDs < 10, P < 0.01). The ICER ranged from 4.5$ to
23.6$ per unit of change of the considered outcomes for the acute
patients and from 0.0$ to 4.5$ for the chronic patients. Formal
willingness to pay and sensitivity analysis were not reported. Given the
very small ICER for the chronic patients, chiropractic care appears
relatively cost effective. The interpretation is less clear for acute
patients, but chiropractic and medical care appear to perform
comparably. Our overall assessment of the study lead us to rate this
study as high quality, because it considered all the costs and outcomes
relevant to the perspective of the analysis.
Kominski et al. [56] conducted a cost-minimization analysis alongside the randomized controlled trial reported by Hurwitz[45, 46]
from the perspective of the healthcare provider group. The authors
recruited Health Maintenance Organization (HMO) patients from three
large medical group practices in Southern California, US. Chiropractic
care (n = 162) was compared to medical care (n = 162), medical care
combined with physical therapy (n = 167) and chiropractic care combined
with physical modalities (n = 163). The medical group received capitated
payments from the insurer. The costs in this study were imputed using
CPT codes and a Medicare fee schedule. The following direct costs were
considered: offices visits, diagnostic and therapeutic services. The
mean total cost for chiropractic care (769$) was significantly higher
than medical care (647$) without producing significantly better clinical
outcomes. The addition of physical therapy (1070$) to medical care and
physical modalities to chiropractic care (790$) also generated greater
costs for similar clinical outcomes. Sensitivity analyses were not
reported. The study quality was rated as medium, because the healthcare
provider group used a remuneration system that likely differed from the
Medicare one. As a consequence, the method used for cost imputation
might not reflect the actual cost of the healthcare provider group.
Additionally, medication costs were not considered. Inclusion of these
costs might considerably influence the overall care cost, and in
particular the medical care costs, and thereby the study conclusions.
In
summary, according to the Slavin’s best-evidence synthesis approach,
the level of evidence of the economic findings relating to chiropractic
compared to medical care is mixed as the three included studies reported
inconsistent conclusions regarding chiropractic care.
Discussion
Summary of findings
We
identified six clinical effectiveness RCTs and three full economic
evaluations. Overall, individual studies showed similar effects of
chiropractic care compared to exercise therapy, physical therapy or
medical care for the treatment of low back pain regardless of type of
outcome, and the risk of bias was low in five out of six included
studies. Similarly, the pooled results revealed no significant
difference in effectiveness between providers groups. No serious adverse
events were reported for any treatment approaches. The three full
economic evaluation studies comparing chiropractic care to medical care
were of low to high methodological quality. These studies provided
conflicting results regarding cost-effectiveness, and the resulting
level of evidence is mixed.
Unfortunately, very few
studies met our inclusion criteria and all our effect estimates
regarding primary and secondary outcomes came from one or two studies.
Additionally, two of our pooled estimates included a considerable level
of heterogeneity [59].
Therefore, future high quality studies are likely to influence effect
estimates. In three of the included clinical effectiveness studies, we
found individual outcomes that were not in concordance with our overall
findings. Most notable was the study by Petersen et al., in which
physical therapy care resulted in better global improvement at three
months and higher functional status at 12 months, compared to
chiropractic care in a population of subacute/chronic LBP [53]. When results were pooled with those from the other available studies for functional status at three [51] and 12 months [43, 44], the heterogeneity was considerable [59].
The inconsistent results can be explained by differences in settings
(studies conducted in Denmark, UK or US); subpopulations
(subacute/chronic vs. mixed symptom duration), and physical therapy
approaches (McKenzie method vs. non-specified physical therapy). We
found one study, which favoured chiropractic care over physical therapy
care in a mixed duration LBP population regarding global improvement at
one month [43, 44].
Finally, during our data extraction for the pooled effect estimates we
found one outcome (the mental subscale of the SF-36 at the three months
follow-up) that favoured chiropractic care over exercise therapy care in
the study by Bronfort et al. [50].
The authors did not report this difference because they performed a
multivariate analysis (instead of a final score comparison), which led
them to report a non-significant difference.
The
existing literature is currently too limited to allow for a synthesis
of economic evaluations robust enough to offer guidance to decision
makers, referring healthcare provider and patients about the
cost-effectiveness of chiropractic compared to other types of care. Two
out of three included economic evaluations had serious methodological
limitations due to low sample size and omission of direct medical costs
that could potentially impact the conclusions. Further, it is difficult
to appreciate the robustness of the conclusions of the economic
evaluations considering that sensitivity analyses were not reported.
Consistency of findings with other studies and reviews
Our
results regarding the effectiveness of chiropractic care are consistent
with previous reviews comparing chiropractors to other provider groups [21, 22] and SMT to other treatment modalities [24–26].
All have concluded that there is no clear superiority for any provider
group or modality. Regarding economic evaluations, older reports [60, 61]
have concluded that chiropractic care is highly cost-effective because
of the relatively low consultation fee and the limited use of advanced
diagnostic imaging. However, more recent rigorous systematic reviews of
partial economic evaluations have failed to show an economic advantage
of one type of care over another [21, 22]. This is consistent with the findings from our review based on a limited number of full economic evaluations.
Strengths and limitations of these reviews
To
our knowledge this is the first synthesis that exclusively considers
pragmatic trials of chiropractic care without including fastidious
trials of SMT. A comprehensive search was conducted to identify all
relevant studies and a rigorous methodology was applied. The extraction
process was performed in accordance with current guidelines and an
experienced health economist supported the economic evaluations.
Limiting our search to the past 25 years enabled us to select
publications that were compatible with contemporary healthcare delivery.
By only considering full economic evaluations and trials at a low risk
of bias, we aimed to derive conclusions from more robust evidence.
Our
review has limitations. First, we did not search the grey literature
for clinical effectiveness studies. McAuley et al. showed that the
inclusion of results from the grey literature tend to decrease
effectiveness estimates in meta-analyses because the unpublished studies
tend to report smaller treatment effects [62].
Second, critical appraisal requires scientific judgment that may vary
among reviewers. This potential bias was minimized by training reviewers
to use a standardized critical appraisal tool and using a consensus
process among reviewers to reach decisions regarding scientific
admissibility. Most of the original between-group differences and pooled
estimates in our meta-analysis did not favour a specific provider
group, and we believe it is unlikely that the inclusion of unpublished
grey literature would change our conclusions. Third, the low number of
clinical trials prevents us from conducting a meaningful investigation
for publication bias. Fourth, the majority of the included clinical
effectiveness studies (three out of five) and all three economic
evaluations were conducted in the United States. Caution should
therefore be used when generalizing our findings to other settings or
jurisdictions. With respect to economic evaluations in particular, local
healthcare systems and insurance plans may have a higher impact on cost
than the type of healthcare provider [55].
Recommendations for future researches
Our
search retrieved only a limited number of pragmatic clinical trials
comparing chiropractic care to other types of care and only one high
quality, full economic evaluation. We suggest therefore that future high
quality pragmatic trials be conducted in parallel with full economic
evaluations considering all relevant direct and indirect costs. The
perspective of the economic evaluation should be clearly specified since
it bears influence on the relevance of the health effects and cost
considered. In addition, future studies should consider the impact of
chiropractic care on return to work and include loss of income and wage
compensation, a major component of indirect cost relevant to patients,
the employers and society. Small differences in work absenteeism
(indirect cost) have previously shown to have considerable impact on
cost and the potential to reverse conclusions based on direct costs only
[63, 64].
To facilitate the interpretation and decision-making process about
types of care, we also suggest that future economic evaluations conduct
willingness to pay and sensitivity analyses. Due to the large numbers of
fastidious trials investigating the efficacy of SMT of LBP, researchers
have previously called for a moratorium on future RCTs [26, 65].
However, we believe that additional pragmatic, practice-based studies
will help clarify whether chiropractic care is truly equivalent to other
types of care in terms of effectiveness and cost. It is likely that, on
average, there is not much difference between the different
alternatives; however there may be heterogeneous treatment effects, i.e.
some treatments that are cost-effective for some and not for others.
Future studies could help elucidate this issue.
Conclusion
Moderate
evidence suggests that chiropractic care for LBP appears to be equally
effective as physical therapy. Limited evidence suggests the same
conclusion when chiropractic care is compared to exercise therapy and
medical care although no firm conclusion can be reached at this time. No
serious adverse events were reported for any type of care. Our review
was also unable to clarify whether chiropractic or medical care is more
cost-effective. Given the limited available evidence, the decision to
seek or to refer patients for chiropractic care should be based on
patient preference and values. Future studies are likely to have an
important impact on our estimates as these were based on only a few
admissible studies.
Acknowledgments
The authors would like to thank Heather Owens for the linguistic revision on the manuscript.
Abbreviations
| AMD | Adjusted Mean Difference |
| BMJ | British Medical Journal |
| CADTH | Canadian Agency for Drugs and Technologies in Health |
| CIHI | Canadian Institute for Health Information |
| CIHR | Canadian Institute of Health Research |
| CPGs | Clinical Practice Guidelines |
| CPT | Current Procedural Terminology |
| DC | Doctor of Chiropractic |
| DCPm | Chiropractic care with physical modalities |
| GDPD | Gross Domestic Product Deflator |
| HMO | Health Maintenance Organization |
| ICL | Index to Chiropractic Literature |
| LBP | Low Back Pain |
| MD | Medical Doctor |
| MD/DO | Medical Doctor or Doctor of Osteopathy |
| MDPt | Medical Doctor and Physical therapy |
| NICE | National Institute for Health and Care Excellence |
| PPP | Purchasing Power Parities |
| QALYs | Quality Adjusted Life Years |
| RCTs | Randomized controlled trial |
| SD | Standard Deviation |
| SMT | Spinal Manipulative Therapy |
| Sx/ED | Surgeons and Emergency Department |
| US | United-States |
| USD | United-States Dollard |
| UK | United Kingdom |
| VAS | Visual Analogue Scale |
Funding Statement
Canadian Institutes of Health Research to Marc-André Blanchette.
The
authors received no specific funding for this work. Participation in
this work is paid by in kind contributions from the authors’ respective
funders and institutions. The publication fees were paid by the lead
author’s PhD fellowship granted by the Canadian Institute of Health
Research. Dr. Stochkendahl’s position is funded by the Danish
Chiropractic Research Foundation. Dr. Bussieres’s position at McGill
University is funded by the Canadian Chiropractic Research Foundation.
The funders had no role in study design, data collection and analysis,
decision to publish, or preparation of the manuscript.Data Availability
All relevant data are within the paper and its Supporting Information files.
References
1. Deyo RA, Mirza SK, Martin BI. Back pain prevalence and visit rates: estimates from U.S. national surveys, 2002. Spine (Phila Pa 1976). 2006;31(23):2724–7. Epub 2006/11/02. doi: 10.1097/01.brs.0000244618.06877.cd 00007632-200611010-00014 [pii]. . [PubMed]
2. Leroux I, Dionne CE, Bourbonnais R, Brisson C. Prevalence of musculoskeletal pain and associated factors in the Quebec working population. Int Arch Occup Environ Health. 2005;78(5):379–86. Epub 2005/04/22. doi: 10.1007/s00420-004-0578-2 . [PubMed]
3. Druss BG, Marcus SC, Olfson M, Pincus HA. The most expensive medical conditions in America. Health affairs (Project Hope). 2002;21(4):105–11. Epub 2002/07/16. . [PubMed]
4. Asklof T, Martikainen J, Kautiainen H, Haanpaa M, Kiviranta I, Pohjolainen T. Paid
expenditures and productivity costs associated with permanent
disability pensions in patients with spinal disorders: Nationwide
Finnish Register-based Study, 1990–2010. Eur Spine J. 2015. Epub 2015/01/31. doi: 10.1007/s00586-015-3775-7 . [PubMed]
5. Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al.
Years lived with disability (YLDs) for 1160
sequelae of 289 diseases and injuries 1990–2010: a systematic analysis
for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2163–96. Epub 2012/12/19. S0140-6736(12)61729-2 [pii] doi: 10.1016/S0140-6736(12)61729-2 . [PubMed]
6. Hoy D, March L, Brooks P, Blyth F, Woolf A, Bain C, et al.
The global burden of low back pain: estimates from the Global Burden of Disease 2010 study. Annals of the Rheumatic Diseases. 2014;73(6):968–74. doi: 10.1136/annrheumdis-2013-204428
[PubMed]
7. Chou R, Qaseem A, Snow V, Casey D, Cross JT Jr., Shekelle P, et al.
Diagnosis and treatment of low back pain: a
joint clinical practice guideline from the American College of
Physicians and the American Pain Society. Annals of internal medicine. 2007;147(7):478–91. Epub 2007/10/03. 147/7/478 [pii]. . [PubMed]
8. Schmidt CO, Raspe H, Pfingsten M, Hasenbring M, Basler HD, Eich W, et al.
Back pain in the German adult population: prevalence, severity, and sociodemographic correlates in a multiregional survey. Spine (Phila Pa 1976). 2007;32(18):2005–11. Epub 2007/08/19. doi: 10.1097/BRS.0b013e318133fad8 00007632-200708150-00014 [pii]. . [PubMed]
9. Cassidy JD, Carroll LJ, Côté P. The Saskatchewan Health and Back Pain Survey: The Prevalence of Low Back Pain and Related Disability in Saskatchewan Adults. Spine. 1998;23(17):1860–6. [PubMed]
10. Foster NE, Hartvigsen J, Croft PR. Taking
responsibility for the early assessment and treatment of patients with
musculoskeletal pain: a review and critical analysis. Arthritis Res Ther. 2012;14(1):205 Epub 2012/03/13. ar3743 [pii] doi: 10.1186/ar3743 ; PubMed Central PMCID: PMC3392833. [PMC free article] [PubMed]
11. Davis MA, Yakusheva O, Gottlieb DJ, Bynum JP. Regional Supply of Chiropractic Care and Visits to Primary Care Physicians for Back and Neck Pain. J Am Board Fam Med. 2015;28(4):481–90. Epub 2015/07/15. doi: 10.3122/jabfm.2015.04.150005 ; PubMed Central PMCID: PMCPMC4512163. [PMC free article] [PubMed]
12. Whedon JM, Song Y, Davis MA, Lurie JD. Use of chiropractic spinal manipulation in older adults is strongly correlated with supply. Spine (Phila Pa 1976). 2012;37(20):1771–7. Epub 2012/04/11. doi: 10.1097/BRS.0b013e31825762b7 ; PubMed Central PMCID: PMCPMC3414681. [PMC free article] [PubMed]
13. Whedon JM, Goertz CM, Lurie JD, Stason WB. Beyond
spinal manipulation: should Medicare expand coverage for chiropractic
services? A review and commentary on the challenges for policy makers. J Chiropr Humanit. 2013;20(1):9–18. Epub 2014/07/30. doi: 10.1016/j.echu.2013.07.001 ; PubMed Central PMCID: PMCPMC4111075. [PMC free article] [PubMed]
14. Astin JA. Why patients use alternative medicine: results of a national study. Jama. 1998;279(19):1548–53. [PubMed]
15. Lonnberg F. [The management of back problems among the population. I. Contact patterns and therapeutic routines]. Ugeskr Laeger. 1997;159(15):2207–14. Epub 1997/04/07. . [PubMed]
16. Wolsko PM, Eisenberg DM, Davis RB, Kessler R, Phillips RS. Patterns and perceptions of care for treatment of back and neck pain: results of a national survey. Spine (Phila Pa 1976). 2003;28(3):292–7; discussion 8. Epub 2003/02/05. doi: 10.1097/01.BRS.0000042225.88095.7C . [PubMed]
17. Kooijman M, Swinkels I, Leemrijse C, de Bakker D, Veenhof C. National Information Service of Allied Health Care. 2011.
18. Hurwitz EL, Chiang LM. A
comparative analysis of chiropractic and general practitioner patients
in North America: findings from the joint Canada/United States Survey of
Health, 2002–03. BMC Health Serv Res. 2006;6:49 Epub 2006/04/08. 1472-6963-6-49 [pii] 10.1186/1472-6963-6-49 . [PMC free article] [PubMed]
19. Cote P, Cassidy JD, Carroll L. The treatment of neck and low back pain: who seeks care? who goes where?
Medical care. 2001;39(9):956–67. Epub 2001/08/15. . [PubMed]
20. Kirby ER, Broom AF, Sibbritt DW, Refshauge KM, Adams J. Health
care utilisation and out-of-pocket expenditure associated with back
pain: a nationally representative survey of Australian women. PLoS One. 2013;8(12):e83559 Epub 2014/01/01. doi: 10.1371/journal.pone.0083559 ; PubMed Central PMCID: PMCPMC3869794. [PMC free article] [PubMed]
21. Baldwin ML, Cote P, Frank JW, Johnson WG. Cost-effectiveness studies of medical and chiropractic care for occupational low back pain. a critical review of the literature. Spine J. 2001;1(2):138–47. Epub 2003/11/01. S1529-9430(01)00016-X [pii]. . [PubMed]
22. Brown A, Angus D, Chen S, Tang Z, Milne S, Pfaff J, et al.
Costs and outcomes of chiropractic treatment for low back pain (Structured abstract). Health Technology Assessment Database [Internet]. 2005; (2):[88 p.]. Available from: http://onlinelibrary.wiley.com/o/cochrane/clhta/articles/HTA-32005000361/frame.html.
23. Gartlehner G, Hansen RA, Nissman D, Lohr KN, Carey TS. A simple and valid tool distinguished efficacy from effectiveness studies. Journal of clinical epidemiology. 2006;59(10):1040–8. Epub 2006/09/19. doi: 10.1016/j.jclinepi.2006.01.011 . [PubMed]
24. Rubinstein SM, Terwee CB, Assendelft WJ, de Boer MR, van Tulder MW. Spinal manipulative therapy for acute low-back pain. Cochrane Database Syst Rev. 2012;9:Cd008880 Epub 2012/09/14. doi: 10.1002/14651858.CD008880.pub2 . [PubMed]
25. Rubinstein SM, van Middelkoop M, Assendelft WJ, de Boer MR, van Tulder MW. Spinal manipulative therapy for chronic low-back pain: an update of a Cochrane review. Spine (Phila Pa 1976). 2011;36(13):E825–46. Epub 2011/05/20. doi: 10.1097/BRS.0b013e3182197fe1 00007632-201106010-00016 [pii]. . [PubMed]
26. Rubinstein SM, Terwee CB, Assendelft WJ, de Boer MR, van Tulder MW. Spinal manipulative therapy for acute low back pain: an update of the cochrane review. Spine (Phila Pa 1976). 2013;38(3):E158–77. Epub 2012/11/22. doi: 10.1097/BRS.0b013e31827dd89d . [PubMed]
27. Shekelle PG, Adams AH, Chassin MR, Hurwitz EL, Brook RH. Spinal manipulation for low-back pain. Annals of internal medicine. 1992;117(7):590–8. Epub 1992/10/01. . [PubMed]
28. Stano M, Haas M, Goldberg B, Traub PM, Nyiendo J. Chiropractic and medical care costs of low back care: results from a practice-based observational study. Am J Manag Care. 2002;8(9):802–9. . [PubMed]
29. Walker BF, French SD, Grant W, Green S. A Cochrane review of combined chiropractic interventions for low-back pain. Spine (Phila Pa 1976). 2011;36(3):230–42. Epub 2011/01/21. doi: 10.1097/BRS.0b013e318202ac73 . [PubMed]
30. Busse JW, Jacobs C, Ngo T, Rodine R, Torrance D, Jim J, et al.
Attitudes toward chiropractic: a survey of North American orthopedic surgeons. Spine (Phila Pa 1976). 2009;34(25):2818–25. Epub 2009/11/17. doi: 10.1097/BRS.0b013e3181c1512f . [PubMed]
31. Blanchette M-A, Rivard M, Dionne C, Cassidy JD. Chiropractors’ characteristics associated with physician referrals: results from a survey of Canadian Chiropractors. J Manipulative Physiol Ther
2015;38(6):395–406. doi: 10.1016/j.jmpt.2014.11.001
[PubMed]
32. Nahal G, Hunnisett A, Cunliffe C. General practitioner referral for musculoskeletal therapies: Why physiotherapy and not chiropractic?
Journal of Chiropractic Education. 2015;29(1):82.
33. Dagenais S, Tricco AC, Haldeman S. Synthesis of recommendations for the assessment and management of low back pain from recent clinical practice guidelines. Spine J. 2010;10(6):514–29. Epub 2010/05/25. S1529-9430(10)00288-3 [pii] doi: 10.1016/j.spinee.2010.03.032 . [PubMed]
34. Palmer S, Torgerson DJ. Economic notes: definitions of efficiency. Bmj. 1999;318(7191):1136 Epub 1999/04/24. ; PubMed Central PMCID: PMCPmc1115526. [PMC free article] [PubMed]
35. Drummond MF, Sculpher M, Torrance G, O’Brien B, Stoddart G. Methods for the economic evaluation of health care programmes
New York: Oxford University Press;
2005.
36. Briggs AH, O'Brien BJ. The death of cost-minimization analysis?
Health economics. 2001;10(2):179–84. Epub 2001/03/17. doi: 10.1002/hec.584 . [PubMed]
37. Blanchette MA, Bussieres A, Stochkendahl MJ, Boruff J, Harrison P. Effectiveness and economic evaluation of chiropractic care for the treatment of low back pain: a systematic review protocol. Syst Rev. 2015;4:30 Epub 2015/04/16. doi: 10.1186/s13643-015-0015-5 ; PubMed Central PMCID: PMCPMC4369074. [PMC free article] [PubMed]
38. Furlan AD, Pennick V, Bombardier C, van Tulder M. 2009 updated method guidelines for systematic reviews in the Cochrane Back Review Group. Spine (Phila Pa 1976). 2009;34(18):1929–41. Epub 2009/08/15. doi: 10.1097/BRS.0b013e3181b1c99f . [PubMed]
39. Drummond MF, Sculpher MJ, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the Economic Evaluation of Health Care Programmes
3ed.
New York: Oxford University Press; 2005.
40. Tompa
E, Culyer AJ, Dolinschi R. Economic Evaluation of Interventions for
Occupational Health and Safety Developing Good Practice
New York: Oxford University Press; 2008.
41. Drummond MF, Jefferson TO. Guidelines for authors and peer reviewers of economic submissions to the BMJ. The BMJ Economic Evaluation Working Party. BMJ. 1996;313(7052):275–83. Epub 1996/08/03. ; PubMed Central PMCID: PMC2351717. [PMC free article] [PubMed]
42. group CBR. [cited 2014 June 20th]. Available from: http://back.cochrane.org/forms.
43. Meade TW, Dyer S, Browne W, Frank AO. Randomised comparison of chiropractic and hospital outpatient management for low back pain: results from extended follow up. Bmj. 1995;311(7001):349–51. Epub 1995/08/05. ; PubMed Central PMCID: PMCPmc2550426. [PMC free article] [PubMed]
44. Meade TW, Dyer S, Browne W, Townsend J, Frank AO. Low back pain of mechanical origin: randomised comparison of chiropractic and hospital outpatient treatment. Bmj. 1990;300(6737):1431–7. Epub 1990/06/02. ; PubMed Central PMCID: PMCPmc1663160. [PMC free article] [PubMed]
45. Hurwitz EL, Morgenstern H, Harber P, Kominski GF, Belin TR, Yu F, et al.
A randomized trial of medical care with and
without physical therapy and chiropractic care with and without physical
modalities for patients with low back pain: 6-month follow-up outcomes
from the UCLA low back pain study. Spine. 2002;27(20):2193–204. . [PubMed]
46. Hurwitz EL, Morgenstern H, Kominski GF, Yu F, Chiang LM. A
randomized trial of chiropractic and medical care for patients with low
back pain: eighteen-month follow-up outcomes from the UCLA low back
pain study. Spine. 2006;31(6):611–21; discussion 22. . [PubMed]
47. Shemilt I, Thomas J, Morciano M. A web-based tool for adjusting costs to a specific target currency and price year. Evidence & Policy: A Journal of Research, Debate and Practice. 2010;6(1):51–9.
48. Slavin RE. Best evidence synthesis: an intelligent alternative to meta-analysis. Journal of clinical epidemiology. 1995;48(1):9–18. Epub 1995/01/01. 0895-4356(94)00097-A [pii]. . [PubMed]
49. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ. 2009;339:b2535 Epub 2009/07/23. ; PubMed Central PMCID: PMC2714657. doi: 10.1136/bmj.b2535 [PMC free article] [PubMed]
50. Bronfort G, Maiers MJ, Evans RL, Schulz CA, Bracha Y, Svendsen KH, et al.
Supervised exercise, spinal manipulation, and home exercise for chronic low back pain: A randomized clinical trial. Spine Journal. 2011;11(7):585–98. http://dx.doi.org/10.1016/j.spinee.2011.01.036. doi: 10.1016/j.spinee.2011.01.036 [PubMed]
51. Cherkin DC, Deyo RA, Battie M, Street J, Barlow W. A
comparison of physical therapy, chiropractic manipulation, and
provision of an educational booklet for the treatment of patients with
low back pain. N Engl J Med. 1998;339(15):1021–9. . [PubMed]
52. Herzog W, Conway PJ, Willcox BJ. Effects of different treatment modalities on gait symmetry and clinical measures for sacroiliac joint patients. J Manipulative Physiol Ther. 1991;14(2):104–9. . [PubMed]
53. Petersen T, Larsen K, Nordsteen J, Olsen S, Fournier G, Jacobsen S. The
McKenzie method compared with manipulation when used adjunctive to
information and advice in low back pain patients presenting with
centralization or peripheralization: a randomized controlled trial. Spine. 2011;36(24):1999–2010. http://dx.doi.org/10.1097/BRS.0b013e318201ee8e. doi: 10.1097/BRS.0b013e318201ee8e [PubMed]
54. Haas M, Sharma R, Stano M. Cost-effectiveness of medical and chiropractic care for acute and chronic low back pain. J Manipulative Physiol Ther. 2005;28(8):555–63. . [PubMed]
55. Butler RJ, Johnson WG. Adjusting rehabilitation costs and benefits for health capital: the case of low back occupational injuries. J Occup Rehabil. 2010;20(1):90–103. http://dx.doi.org/10.1007/s10926-009-9206-z. doi: 10.1007/s10926-009-9206-z [PubMed]
56. Kominski GF, Heslin KC, Morgenstern H, Hurwitz EL, Harber PI. Economic evaluation of four treatments for low-back pain: results from a randomized controlled trial. Med Care. 2005;43(5):428–35. . [PubMed]
57. Mosley CD, Cohen IG, Arnold RM. Cost-effectiveness of chiropractic care in a managed care setting. Am J Manag Care. 1996;2:280–2.
58. Mushinski M. Treatment of back pain: outpatient service charges, 1993. Stat Bull Metrop Insur Co.
1995;76:32–9.
59. Deeks JJ, Higgins J, Altman DG. Analysing Data and Undertaking Meta‐Analyses. Cochrane Handbook for Systematic Reviews of Interventions: Cochrane Book Series. 2008:243–96.
60. Manga
P, Angus DE. Enhanced chiropractic coverage under OHIP as a means of
reducing health care costs, attaining better health outcomes and
achieving equitable access to select health services: Faculty of
Administration, University of Ottawa = Faculté d'administration,
Université d'Ottawa; 1998.
61. Manga
P, Angus D, Papadopoulos C, Swan W. The effectiveness and
cost-effectiveness of chiropractic management of low-back pain: Pran
Manga & Associates Incorporated; 1993.
62. McAuley L, Pham B, Tugwell P, Moher D. Does the inclusion of grey literature influence estimates of intervention effectiveness reported in meta-analyses?
Lancet. 2000;356(9237):1228–31. Epub 2000/11/10. doi: 10.1016/s0140-6736(00)02786-0 . [PubMed]
63. Fayssoux R, Goldfarb NI, Vaccaro AR, Harrop J. Indirect costs associated with surgery for low back pain-a secondary analysis of clinical trial data. Popul Health Manag. 2010;13(1):9–13. Epub 2010/02/18. doi: 10.1089/pop.2009.0061 . [PubMed]
64. Ivanova JI, Birnbaum HG, Kantor E, Schiller M, Swindle RW. Duloxetine use in employees with low back pain: treatment patterns and direct and indirect costs. Pain Med. 2014;15(6):1015–26. Epub 2014/02/18. doi: 10.1111/pme.12362 . [PubMed]
65. Hurwitz EL. Commentary:
Exercise and spinal manipulative therapy for chronic low back pain:
time to call for a moratorium on future randomized trials?
Spine J. 2011;11(7):599–600. Epub 2011/08/09. doi: 10.1016/j.spinee.2011.04.021 . [PubMed]
Articles from PLoS ONE are provided here courtesy of Public Library of Science
