PRECIS-2: a tool to improve the applicability of randomised controlled trials

Abstract

Background: RCTs are the best design to evaluate the effect of different interventions but randomisation does not itself promote the applicability of the results to situations other than the one in which the trial was done. PRECIS is a tool that helps trialists consider the effects of their design decisions on applicability. Aim: To produce an improved and validated version of PRECIS. Methods: The study has three phases. Phase 1 involves brainstorming and a two-round Delphi survey of authors who cited PRECIS. The Delphi results will then be discussed and alternative versions of PRECIS-2 developed and user-tested by experienced trialists. Phase 3 will evaluate the validity and reliability of the most promising PRECIS-2 candidate using a sample of 15-20 trials rated by 15 other trialists. Results: Brainstorming sessions identified the PRECIS presentation (a wheel), lack of a scoring system and domain weighting as issues for exploration in the Delphi. Ninety individuals were invited to complete round 1 of the Delphi; completed responses were received from 34. Many respondents wanted a scoring system, were unhappy about presentation format and suggested several additional domains for PRECIS-2. Based on these responses, round 2 of the Delphi tested specific scoring alternatives, tabular vs a wheel presentation and new domains. Early responses to round 2 support using both wheel and tabulated forms of PRECIS, several new domains (eg. recruitment setting), 1-7 scoring and show continued uncertainty over weighting. The next stage will use the Delphi suggestions to create alternative versions of PRECIS-2 for user-testing in spring 2013. Conclusions: We have concrete suggestions for improving PRECIS and a growing list of enthusiastic individuals interested in contributing to this work. By the end of 2013 we expect to have a validated PRECIS-2.