Article type
Year
Abstract
Introduction: The Cochrane Collaboration aims at the writing and dissemination of systematic reviews for all clinical areas. The methodology for conducting systematic reviews, as described in the Toolkit and required for entering into the Review Manager (RevMan), has mainly been developed in clinical areas where large, well-performed randomized clinical trials (RCTs) exist. RCTs in these areas generally have uniform patient categories, outcome measures and follow-up moments, and are therefore eligible for statistical pooling.
Methods: For the Cochrane review "Spinal manipulation for low back pain" a protocol was written according to the guidelines in the Toolkit. We already knew that the RCTs on this topic varied considerably in size, type of patients, methodological quality and outcome measurement. To enable a sensible pooling we planned to extract data on: patients (4 different characteristics), outcomes (4 different types) and timing of follow-up (short-term, intermediate and long-term). The quality assessment list contained 8 validity items, instead of the single item "concealment of allocation" which is currently available in RevMan. The protocol has now been accepted, and as a pilot we applied the protocol to the 8 chiropractic RCTs available on this subject.
Results: We tried to pool the 8 chiropractic studies. Most outcome measures, however, in combination with the various follow-up moments, were simply not covered by enough RCTs to perform a pooling which was clinically sensible. This was mainly caused by insufficient reporting of essential details and a substantial heterogeneity in the outcome measures and follow-up timing. Therefore, we were only able discuss this subset of studies on a systematic "qualitative" study-to-study basis. A major constraint was the low adherence on many of the validity items.
Discussion: To our opinion a uniform, quantitative, presentation of systematic reviews, as presently required by the Cochrane Collaboration, will not apply to all topics. To enable inclusion of systematic "qualitative" reviews of methodologically "underdeveloped" subjects like ours, RevMan should have more manuscript processing options. In addition, the assessment of the validity of the included RCTs should receive more attention.
Methods: For the Cochrane review "Spinal manipulation for low back pain" a protocol was written according to the guidelines in the Toolkit. We already knew that the RCTs on this topic varied considerably in size, type of patients, methodological quality and outcome measurement. To enable a sensible pooling we planned to extract data on: patients (4 different characteristics), outcomes (4 different types) and timing of follow-up (short-term, intermediate and long-term). The quality assessment list contained 8 validity items, instead of the single item "concealment of allocation" which is currently available in RevMan. The protocol has now been accepted, and as a pilot we applied the protocol to the 8 chiropractic RCTs available on this subject.
Results: We tried to pool the 8 chiropractic studies. Most outcome measures, however, in combination with the various follow-up moments, were simply not covered by enough RCTs to perform a pooling which was clinically sensible. This was mainly caused by insufficient reporting of essential details and a substantial heterogeneity in the outcome measures and follow-up timing. Therefore, we were only able discuss this subset of studies on a systematic "qualitative" study-to-study basis. A major constraint was the low adherence on many of the validity items.
Discussion: To our opinion a uniform, quantitative, presentation of systematic reviews, as presently required by the Cochrane Collaboration, will not apply to all topics. To enable inclusion of systematic "qualitative" reviews of methodologically "underdeveloped" subjects like ours, RevMan should have more manuscript processing options. In addition, the assessment of the validity of the included RCTs should receive more attention.