We thank the members of Cochrane Effective Practice and Organisation of Care for their valuable input during the update of this review. The Norwegian Satellite of the EPOC Group receives funding from the Norwegian Agency for Development Cooperation (Norad), via the Norwegian Institute of Public Health, to support review authors in the production of their reviews. We would like to thank Jan Odgaard‐Jenssen for his guidance, advice, and assistance with statistical meta‐analyses and sensitivity analyses. We thank Marit Johnson who advised on the search strategy and helped with computerised searches, as reported in this update. We would also like to acknowledge Simon Lewin for his appreciated editorial input into the updated review, as well as the following editors and peer referees, who provided comments to improve the protocol: Claire Glenton, Jane Noyes, Connor Emdin, and Claudia Maier; and to Dolores P. Matthews for copyediting this review.

We would like to acknowledge the following people, who were involved in the original review: Steve Rose and Richard Heywood, who advised on the search strategy and helped with computerised searches (original searches until 2002); Michelle Sergison and Bonnie Sibbald, who helped design the review and assisted with early data extraction; and Shirley Halliwell, who obtained study articles and helped to screen papers suitable for data extraction; David Reeves, who helped with statistical analysis in the original review (published in 2005). Finally, we have removed David Reeves, Rosella Hermens, Joze Braspennig, and Richard Grol as authors of this updated review, as owing to other obligations they lack sufficient time to commit to the process of this update. With regret, we have also removed Bonnie Sibbald from the list of review authors, as Bonnie was (together with Michelle Sergison and Miranda Laurant) one of the initiators of this systematic review and had been intensively involved in the review update until the time of her retirement. We would like to thank Bonnie for all of her input into this review until now.

The Effective Health Care Research Consortium provided funding to make this review open access. The Consortium is funded by UK aid from the UK Government for the benefit of developing countries (Grant: 5242). The views expressed in this review do not necessarily reflect UK government policy.