1. Main characteristics of included studies.

Author	Country	Type of CBT	Type of control group	Duration CBT (weeks)	Number of CBT sessions Total treatment time CBT (hours)	Number of patients in CBT group % women	Number of patients in control group % women
Alda 2011 *	Spain	CBT	TAU	12	6 15	57 95	56 96
Ang 2010 *	USA	CBT	TAU	12	6 3	17 100	15 100
Burckhardt 1994 *	Sweden	CBT	Delayed treatment	6	6 9	28 100	30 100
Castel 2009 *	Spain	CBT	TAU	11	12 18	18 94	12 86
Castel 2012 *	Spain	CBT	TAU	14	14 28	34 94	30 100
Edinger 2005 *	USA	CBT	TAU	6	6 6	16 94	12 100
Falcao 2008 *	Brazil	CBT	TAU	10	20 30	30 100	30 100
Kashikar‐Zuck 2005 **	USA	CBT	Active control	8	8 12	14 100	14 100
Kashikar‐Zuck 2012 **	USA	CBT	Active control	8	8 6	57 95	57 90
King 2002 *	USA	CBT	Delayed treatment	12	12 18	48 100	39 100
Luciano 2011 *	Spain	CBT	TAU	8	8 16	108 95	108 98
Miro 2011 *	Spain	CBT	Active control	6	6 9	20 100	20 100
Nicassio 1997 *	USA	CBT	Active control	10	10 15	36 89	35 89
Oliver 2002 *	USA	Self‐management	TAU	52	10 20	207 96	193 94
Redondo 2004 *	Spain	CBT	Active control	8	8 20	21 100	19 100
Rooks 2007 *	USA	Self‐management	Active control	16	8 16	51 100	50 100
Soares 2002 *	Sweden	CBT	Attention control	10	10 120	18 100	18 100
Thieme 2003 *	Germany	Operant therapy	Active control	5	25 75	42 100	21 100
Thieme 2006a *	Germany	Operant therapy	Attention control	15	15 30	42 100	20 100
Thieme 2006b *	Germany	CBT	Attention control	15	15 30	43 100	20 100
Vlayen 1996 *	Netherlands	CBT	Active control	6	12 18	49 93	43 82
Wigers 1996 *	Norway	CBT	TAU	14	15 30	20 90	20 95
Williams 2010 *	USA	Self‐management	TAU	26	NR	59 95	59 95
Woolfolk 2012 *	USA	CBT	TAU	NR	NR	38 89	38 87

* Studies included only adults  

** Studies included only children and adolescents

NR = Not reported and not provided on request

TAU = Treatment as usual