Background: Many healthcare interventions are of complex nature, consisting of several interacting components. Complex interventions are often described inadequately. A reporting guideline for complex interventions was published in 2012 (Criteria for Reporting the Development and Evaluation of Complex Interventions in healthcare, CReDECI) and was recently checked for its practicability. The reporting guideline was developed following the recommendations of the EQUATOR network but excluding a formal consensus process. Therefore, a consensus process was initiated, to revise the reporting guideline.
Methods: We used a three-phase consensus process consisting of (1) a web-based feedback survey on the published reporting guideline, (2) a face-to-face consensus conference, and (3) a final online review and feedback round to create the revised CReDECI. The consensus process was organized and conducted via the REFLECTION network.
Results: A total of 45 attendees from 16 European countries took part in the face-to-face consensus conference. The revised reporting guideline (CReDECI 2) comprises 13 items on three stages: development, feasibility and piloting, and evaluation of a complex intervention. Each item is illustrated by an explanation and an example. In contrast with most of the available reporting guidelines, CReDECI 2 does not focus on a specific study design, to reflect the use of different qualitative and quantitative designs and methods in the development and evaluation of complex interventions.
Conclusions: CReDECI 2 is a formally consented reporting guideline aiming to improve the reporting quality of the development and evaluation stages of complex interventions in healthcare. Since the guideline does not focus on a specific study design, design-specific reporting guidelines may additionally be used.