Table 3.

Effect sizes of the dependent variables in the CBT and OBT groups in comparison with the AP group at pre-treatment (T1), post-treatment (T2), and 6 months (T3) and 12 months (T4) after treatment

Group
	CBT – AP				OBT – AP
Variable	ES T1–T2	ES T1–T3	ES T1–T4	ES T1–T4a	ES T1–T2	ES T1–T3	ES T1–T4	ES T1–T4a
FIQ – Physical impairment	0.18	0.83	0.84	0.71	0.21	0.37	1.15	1.07
MPI – Pain	0.29	0.40	1.14	0.31	0.33	0.30	1.10	0.62
MPI – Affective distress	0.76	1.39	1.57	0.61	0.22	0.59	0.86	0.72
PRSS – Coping	1.16	1.72	2.66	1.70	0.21	0.73	1.23	0.38
PRSS – Catastrophising	0.62	0.96	1.44	0.54	0.12	0.89	0.97	0.41
Pain behaviour	0.44	0.42	0.57	0.49	0.59	0.72	1.89	1.48
MPI – Solicitous spouse behaviour	0.19	0.41	0.44	0.37	0.43	1.00	1.71	0.57

^aAdjusted ES based on the AP group with the dropout values from baseline carried forward to the 12-month follow-up. Medium (>0.5) and large (>0.8) ESs were bolded. AP, attention-placebo; CBT, cognitive behaviour therapy; ES, effect size; FIQ, Fibromyalgia Impact Questionnaire, MPI, Multidimensional Pain Inventory; OBT, operant behavior therapy; PRSS, Pain Related Self-Statements Scale.