Pérez-Aranda A, Feliu-Soler A, Montero-Marín J, et al. - Researchers investigated whether mindfulness-based stress reduction (MBSR) is effective in reducing functional impairment in people with fibromyalgia (FM). Further, they appraised the role of mindfulness-related constructs as mediators of treatment outcomes in these people. Randomization of 225 participants with FM into 3 study arms was done: MBSR plus treatment-as-usual (TAU), FibroQoL (multicomponent intervention for FM) plus TAU, and TAU alone. Findings suggest the superiority of MBSR to TAU both at posttreatment (large effect sizes) and at follow-up (medium to large effect sizes), and indicate its superiority to FibroQoL posttreatment (medium to large effect sizes), but in the long term, it was only modestly better (significant differences only in pain catastrophizing and fibromyalginess). Immediately posttreatment, the number required to treat for 20% improvement in MBSR vs TAU and FibroQoL was 4.0 (95% confidence interval [CI] = 2.1-6.5) and 5.0 (95% CI = 2.7-37.3). For FibroQoL vs TAU, they identified an unreliable number needed to treat value of 9 (not computable 95% CI). Psychological inflexibility and the mindfulness facet acting with awareness mediated the changes produced by MBSR in functional impact.