|The effectiveness of chiropractic for treatment of low back pain: an update and attempt at statistical pooling
|Assendelft W J, Koes B W, van der Heijden G J, Bouter L M
To determine the effectiveness of chiropractic treatment for patients with low-back pain, and to update a previous review (see Other Publications of Related Interest).
MEDLINE and EMBASE were searched from 1966 to 1995 for studies published in the English language; the search terms were provided. The reference lists of relevant studies were also reviewed for additional studies. Abstracts and unpublished studies were excluded.
Study designs of evaluations included in the review
Randomised controlled trials (RCTs) with a follow-up of more than one day were eligible for inclusion. RCTs that used inadequate methods of randomisation were excluded.
Specific interventions included in the review
Studies of chiropractic treatment involving, for example, manipulation or mobilisation of the spine, were eligible for inclusion. The comparison group varied and was pragmatic (e.g. physiotherapy, massage, back school or medical treatment) or placebo (sham procedure, minimal force or massage). Further details were given in the report.
Participants included in the review
Studies of participants with low-back pain were eligible for inclusion. The location of initial referral, duration of pain, and radiating complaints varied between the studies. Further details were given in the report.
Outcomes assessed in the review
Specific inclusion criteria for the outcomes were not given. The outcomes assessed in the included studies were success rate, severity of pain, and back-pain specific and generic functional status. Success rate was defined as the proportion of patients recovered, as determined by the patient or assessor. Physiological variables were not used in the assessment of results.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.
Assessment of study quality
All the studies were assessed according to the following criteria: baseline comparability, generation of allocation sequence, concealment of randomisation, blinding of the patient and assessor, the numbers lost to follow-up, and the use of intention-to-treat analysis (internal validity). Additional criteria were used to assess the quality of the reporting and precision of each individual study. Two reviewers independently assessed the validity of each individual study. Any disagreements were resolved by consensus or by consulting a third reviewer.
The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction. Data were extracted on each outcome and the duration of follow-up, as reported in each individual study. The overall result of each study was reported as either 'positive' or 'negative', according to the interpretation of the original trialist.
Methods of synthesis
How were the studies combined?
The studies were tabulated and combined in a narrative discussion, according to whether the duration of pain was acute (less than 3 weeks) or chronic (more than 3 weeks).
How were differences between studies investigated?
Differences between the studies were discussed according to methodological quality, patient characteristics, type of comparison and outcome measurement.
Results of the review
Eight RCTs (n=1,744) were included. Four of the studies employed a pragmatic control group, one used placebo, and three used both pragmatic and placebo.
Each of the included studies had methodological weaknesses in their internal validity, quality of reporting and precision. Only three studies used adequate methods of randomisation, two studies had low loss to follow-up, and two used an intention- to-treat analysis. The blinding of the patients or outcome assessors was not achieved in the majority of the studies. In addition, the sample size in most of the studies was inadequate. Acute pain.
Three of the four studies that evaluated patients with acute low-back pain found an overall positive improvement in back pain-specific functioning or severity of pain associated with chiropractic treatment at short-term follow-up, compared with control. However, the benefit was not maintained. One further study that combined patients with acute and chronic low-back pain reported a positive success rate associated with chiropractic treatment at short-term follow-up, compared with control. However, the authors stated that the sample size was too small to derive definitive conclusions.
Three of the eight studies found an overall positive improvement in, respectively, back pain-specific functional status, severity of pain and recovery associated with chiropractic treatment, compared with control. One study found an improvement in pain, but not back pain-specific functional status, immediately after the intervention. Three studies found no improvement in back pain-specific functional status or severity of pain. One further study that combined patients with acute and chronic low-back pain reported a positive success rate at short-term follow-up associated with chiropractic treatment, compared with control. However, the authors stated that the sample size was too small to derive definitive conclusions.
There was insufficient evidence to demonstrate the effectiveness of chiropractic treatment for acute or chronic back pain owing to methodological weaknesses and the inadequate reporting of each of the included studies. Further well-conducted trials are required.
The review question was clear in terms of the participants and intervention. The authors reported that studies using inadequate methods of randomisation were not eligible for inclusion. However, it was not possible to determine the method of randmisation in most of the included studies.The search strategy was limited to published studies and was restricted by language, thus the potential for publication and language bias cannot be ruled out. It is unclear whether methods were used to reduce bias when selecting the studies for inclusion or when extracting the data. Two reviewers independently assessed the validity of each included study, thereby reducing the potential for bias.
The authors acknowledged that heterogeneity precluded a statistical pooling. Details of each included study were tabulated. However, the results were not reported separately for patients with acute and chronic back pain, and the overall result presented for each study was based on the interpretation of the original trialist. This makes it difficult for the reader to interpret the results. Furthermore, the reviewers were unable to analyse the level of intervention delivered to the comparison group and how this may influence the apparent effectiveness of chiropractic treatment. Consequently, the authors' conclusion, that there was insufficient evidence on the effectiveness of chiropractic treatment for acute and chronic back pain, is appropriate given the limitations of the review and the evidence presented.
Implications of the review for practice and research
Practice: The authors did not state any implications for practice.
Research: The authors stated that further well-conducted RCTs are required to determine the effectiveness of chiropractic treatment for acute and chronic low-back pain. The authors also stated that guidelines on the conduct and reporting of RCTs evaluating chiropractic treatment are required, and that a register of RCTs should be established.
Assendelft W J, Koes B W, van der Heijden G J, Bouter L M. The effectiveness of chiropractic for treatment of low back pain: an update and attempt at statistical pooling. Journal of Manipulative and Physiological Therapeutics 1996; 19(8): 499-507
Other publications of related interest
Assendelft WJ, Koes BW, van der Heijden GJ, Bouter, LM. The efficacy of chiropractic for back pain: blinded review of relevant randomized clinical trials. J Manipulative Physiol Ther 1992;15:487-94. Assendelft WJJ, Morton SC, Yu EI, Suttorp MJ, Shekelle PG. Spinal manipulative therapy for low back pain. a meta-analysis of effectiveness realtive to other therapies. Ann Intern Med 2003;138:871-81.
Subject indexing assigned by NLM
Chiropractic; Humans; Low Back Pain /therapy; Manipulation, Orthopedic; Treatment Outcome
Date bibliographic record published
Date abstract record published
This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.