Sensitivity of review results to methods used to appraise and incorporate trial quality into data synthesis

STUDY DESIGN: Systematic review. OBJECTIVE: To determine whether results and conclusions on the effectiveness of exercise for workers with neck pain vary with the Cochrane Back Review Group Guidelines and best-evidence synthesis review methods. To identify methodologic weaknesses associated with these review methods that may impact on the validity of their results. SUMMARY OF BACKGROUND DATA: The Cochrane Back Review Group Guidelines and best-evidence synthesis have different approaches to appraising trial quality and incorporating quality into data synthesis. The impact of different review methods on the reproducibility and validity of review results is unknown. METHODS AND RESULTS: Systematic search of Medline, Embase, CINAHL, and Cochrane databases, without language restrictions. Twelve trials were selected. Two review methods were used to appraise trial quality and to incorporate quality into data synthesis. As recommended by the Cochrane Back Review Group Guidelines, trials were assigned quality scores using a scale. Results of all 12 trials were stratified into levels of evidence according to their scores. Based on these results, no treatment recommendation could be formulated. Best-evidence synthesis critically appraised methodology; trials were accepted on the strength of their scientific merit or rejected due to risk of bias. According to the 4 trials accepted for best-evidence synthesis, workers should be activated with exercise given its beneficial effect on patient-perceived recovery. Both the Cochrane Back Review Group Guidelines and best-evidence synthesis reviews were found to have weaknesses associated with their methods. CONCLUSIONS: Review results and conclusions are sensitive to methods for appraising trial quality and incorporating quality into data synthesis when the evidence consists largely of low-quality trials. Both the Cochrane Back Review Group Guidelines and best-evidence synthesis methods were found to have strengths and methodologic weaknesses that healthcare decision-makers should be aware of when interpreting systematic reviews