Cyclobenzaprine and back pain: a meta-analysis

CRD COMMENTARY:

This was a reasonably well-conducted systematic review. The research question was clearly stated, although the types of participants were unclear and the patient demographics were not reported. This information would have been helpful as patient variables such as age, gender, type of back pain and co-morbid conditions, may affect the outcomes. The literature search was comprehensive and efforts were made to identify unpublished research. However, the restriction to English language publications could result in some studies being missed.
Some details of the review process, such as the number of reviewers selecting the studies, were not reported. A validity assessment was carried out, reported and used in the investigation of heterogeneity. Study details were not fully reported in terms of the outcomes. It seemed appropriate to pool the data, although unexplained heterogeneity in the global improvement outcome means that this result should be treated with caution. For the continuous outcomes, the rationale and process for data extraction at three different time points was unclear. The adverse events comparisons were rudimentary.
The authors' conclusion, that the effect of cyclobenzaprine compared with placebo is modest and comes at the price of greater adverse effects, does follow from the results presented. The conclusion that shorter courses of cyclobenzaprine may be better does not seem to be based on strong evidence.