Interdisciplinary rehabilitation of patients with chronic widespread pain: primary endpoint of the randomized, nonblinded, parallel-group IMPROvE trial.

This study examined the functional and psychological outcomes of a 2-week, group-based multicomponent treatment course that targeted patients with chronic widespread pain. Patients (192 included in the intention-to-treat population), all fulfilling the 1990 American College of Rheumatology classification criteria for fibromyalgia, were consecutively recruited from a tertiary care setting and randomized (1:1) to either the treatment course or a waiting list control group. Co-primary outcomes were the Assessment of Motor and Process Skills (AMPS) and SF-36 Mental Composite Score (MCS) evaluated at 6-month follow-up. Primary endpoints were partly achieved with a statistically significant improvement in AMPS activities of daily living motor (group mean difference: 0.20 [95% confidence interval (CI): 0.09 to 0.31] logits; P=.0003) and AMPS activities of daily living process (0.20 [95% CI: 0.12 to 0.27] logits, P<.0001) ability measures, whereas no difference in the SF-36 MCS (1.14 [95% CI: -1.52 to 3.81], P=.40) was observed. Individual patient responses varied, and the proportion of patients achieving a clinically meaningful change of at least 0.3 logits on the AMPS seemed influenced by the reporting of a pending social welfare application at the time of enrollment. We conclude that even in fibromyalgia patients presenting with a substantial disability established over many years, the 2-week multicomponent treatment course resulted in observable improvement of functional ability in a subgroup of patients at 6-month follow-up. This improvement, however, was not reflected in secondary patient reported outcomes, including scores of self-reported functional ability on standardized questionnaires. We suggest including observation-based assessments in future clinical trials focusing on functional outcomes in patients with fibromyalgia.