PCORI

As proposed, the call to use ‘analysis of gaps in the evidence based on systematic reviews’ is much more complex than the requirement in the prior version of the Standard. Given the increased emphasis on using systematic reviews to identify evidence gaps as well as to ensure that PCORI’s documents are as useful and accessible as possible, PCORI should consider making available on its website the best sources of systematic reviews, such as Cochrane, formally known as the Cochrane Collaboration (http://www.cochrane.org/) and Canada’s Health Systems Evidence (https://www.healthsystemsevidence.org/), so researchers have a more solid foundation from which to begin their study. Furthermore, when conducting systematic reviews, the central issue is not necessarily about what is possible, but what is useful and worthwhile. Therefore, we propose that the last sentence be: “In cases where incremental systematic reviews may not be useful over existing literature or in which the effort needed is not worthwhile, the methods used to review the literature should be explained and justified.”

For rare diseases a systematic review is seldom available. This puts undo demand on investigators in a under investigated area.

The last sentence now reads: "In the case where a systematic review is not possible.......". Is a systematic review ever not possible? Even is the evidence for something is sparse, it can still be systematically reviewed. Consider replacing "possible" with "done". {EBort}

Identification of gaps in the evidence is imperative, specially those who have excluded women, children and the elderly. However, ideally evidence-base also should include socio-economic and psychological aspects of the population.

Specifically regarding the statement "in the case where a systematic review is not possible, the methods used to review the literature should be explained and justified": it would be interesting to suggest that these methods should follow as many as possible among the components specified under the Methods section of the PRISMA statement http://goo.gl/BijVhu