Who benefits from CBT for insomnia in primary care? Important patient selection and trial design lessons from longitudinal results of the Lifestyles trial.

STUDY OBJECTIVES: Evaluate long-term effects of group interventions on sleep and pain outcomes in a primary care population of older adults with osteoarthritis pain and sleep disturbance. DESIGN: Double-blind, cluster-randomized controlled trial with 18-mo follow-up. SETTING: Group Health and University of Washington, Seattle, WA, from 2009 to 2011. PARTICIPANTS: Three hundred sixty-seven adults age 60 y and older, with osteoarthritis pain and insomnia symptoms. INTERVENTIONS: Six weekly sessions of group cognitive behavioral therapy for insomnia and pain (CBT-PI), pain alone (CBT-P), and education-only control (EOC) delivered in patients' primary care clinics. MEASUREMENTS AND RESULTS: There were no significant differences between treatment groups in sleep outcomes at 18 mo. This is a change from published significant 9-mo follow-up results for insomnia severity (Insomnia Severity Index) and sleep efficiency. There were no significant treatment differences in pain at either follow-up. Post hoc analyses of participants with greater insomnia and pain severity at baseline (n = 98) showed significant (P = 0.01) 18-mo reductions in pain comparing CBT-PI versus CBT-P (adjusted mean difference [AMD] = -1.29 [95% confidence interval (CI): -2.24,-0.33]). Moderate, albeit nonsignificant, CBT-PI versus EOC treatment effects for insomnia severity (AMD = -1.43 [95% CI: -4.71, 1.86]) and sleep efficiency (AMD = 2.50 [95% CI: -5.04, 10.05]) were also observed. Possible trial design and methodological considerations that may have affected results are discussed. CONCLUSIONS: Results suggest patients with higher levels of comorbid pain and insomnia may be most likely to experience sustained benefit from cognitive behavioral therapy interventions over time, and inclusion of insomnia treatment may yield more clinically meaningful improvements than cognitive behavioral therapy for pain alone. TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT01142349.