The Cochrane Collaboration offers selleck kinase inhibitor a guide for inclusion of nonrandomized studies [59] and it has developed a tool for assessing the risk of bias in both RCT and controlled nonrandomized studies[60]. Conclusions Different study designs addressing the same question yielded varying results, with differences in about half of all examples. The risk of presenting uncertain results without knowing for sure the direction and magnitude of the effect holds true for both nonrandomized and randomized controlled trials, though, the risk of bias and confounding is probably higher in the nonrandomized ones. The integration of multiple study designs in systematic reviews is required if patients should be informed on the many facets of patient relevant issues of health care interventions.

Supporting Information Table S1 PRISMA Checklist. (DOC) Click here for additional data file.(70K, doc) Table S2 Qualitative summary of key messages. Type of review. Systematic review (first 8 papers): Cochrane Systematic Review (Archampong 2012), Health Technology Assessment of National Health Service in UK (Britton 1998), other systematic reviews not issued by Cochrane or HTA (Chambers 2009, Chambers 2010, Chou 2010, Lewsey 2000, Linde 2002, Norris 2005). Non-systematic review (rest of 34 papers): narrative review or editorial or comment or letter. Message. We extracted messages with respect to the question whether nonrandomized studies should be conducted or integrated in systematic reviews to complement available RCTs or replace lacking RCTs. We did not extract data on differences between those two study design on size or direction of effect.

NRS also: We perceived a tendency in Cilengitide the message that nonrandomized studies should also be considered in addition to RCTs in general or to answer specific research questions. RCT only: We perceived a tendency in the message that RCTs are sufficient to answer research questions in clinical trials and in systematic reviews and that nonrandomized studies cannot complement or replace them. Field.