Erratum

After publication of this work [1], we noted that we inadvertently failed to include the complete list of all coauthors. The full list of authors has now been added, and the Authors' contributions and Competing interests section modified accordingly. We are publishing this erratum to update the author list, which is as follows: Karen Overend, Helen Lewis, Della Bailey, Kate Bosanquet, Carolyn Chew-Graham, David Ekers, Samantha Gascoyne, Deborah Hems, John Holmes, Ada Keding, Dean McMillan, Shaista Meer, Jodi Meredith, Natasha Mitchell, Sarah Nutbrown, Steve Parrott, David Richards, Gemma Traviss, Dominic Trépel, Rebecca Woodhouse and Simon Gilbody.