Simplified EPOC standard of study designs considered for inclusion in the present review. Source: Bero L, Eccles M, Grimshaw J, Gruen RL, Mayhew A, Oxman AD, Tavender E, Zwarenstein M, Shepperd S, Paulsen E, Pantoja T, Lewin S, Ballini L. Cochrane Effective Practice and Organisation of Care Group (Cochrane Group Module). About The Cochrane Collaboration (Cochrane Review Groups (CRGs)). The Cochrane Library. Oxford: John Wiley, 2009; adopted by the authors.