Spinal manipulation for low back pain: an updated systematic review of randomized clinical trials

CRD COMMENTARY: This review includes a rigorous scoring of primary studies on 17 stated methodological criteria and reports the most common methodological flaws found. These include lack of baseline comparison of treatment groups, inadequate description of randomisation method, incomplete details of drop-outs, small sample size, lack of blinding of patients, variable effect measures and inadequate analysis and presentation of data. The authors acknowledge that by limiting the literature search they may have omitted some relevant studies. No details are given of the methods used to select studies or to extract data from the included studies. A definition of low back pain which was used as an inclusion criteria for participants would have been helpful, and some indication of patient characteristics would have been useful in assessing generalisability of the results. It is stated that manipulation could be given separately or with other therapeutic modalities, but the reporting of results does not appear to take this into account. Positive and negative outcomes are reported without reference to the sample size of the studies. Despite the considerable heterogeneity among trials there is little exploration or discussion as to possible sources of this heterogeneity. Consideration of definition of inclusion criteria, characteristics of participants, duration of therapy, duration of follow-up, intention-to-treat analysis from raw data where possible, more rigorous evaluation of outcome measures used, weighted effects measures and accounting for specific aspects of quality assessment may have revealed possible sources of heterogeneity. The authors suggest there may be evidence that manipulation is more efficacious in certain subgroups of patients with acute or chronic low back pain. This albeit tentative suggestion does not appear to be supported by the evidence offered. The authors have rigorously assessed the quality of the primary studies of spinal manipulation in patients with low back pain and found no conclusive evidence of efficacy of this therapy. The methodological flaws reported in the primary studies would appear to preclude any other conclusion.