AHRQ series on complex intervention systematic reviews-paper 6: PRISMA-CI extension statement and checklist

PRISMA-CI development followed the Enhancing the QUAlity and Transparency Of health Research Network guidance for extensions and focused on adding or modifying only essential items that are truly unique to complex interventions and are not covered by broader interpretation of current PRISMA guidance. PRISMA-CI provides an important structure and guidance for systematic reviews and meta-analyses for the highly prevalent and dynamic field of complex interventions.