Mid-Treatment Sleep Duration Predicts Clinically Significant Knee Osteoarthritis Pain Reduction at 6 Months: Effects from A Behavioral Sleep Medicine Clinical Trial.

STUDY OBJECTIVES: To determine the relative influence of sleep continuity (sleep efficiency, sleep onset latency, total sleep time, and wake after sleep onset) on clinical pain outcomes within a trial of CBT-I for patients with comorbid knee osteoarthritis and insomnia.

METHODS: Secondary analyses were performed on data from 74 patients with comorbid insomnia and knee osteoarthritis who completed a randomized clinical trial of 8 session Multi-Component Cognitive behavioral therapy for insomnia (CBT-I) versus an active behavioral desensitization control condition (BD), including a 6-month follow-up assessment. Data used herein include daily diaries of sleep parameters, actigraphy data, and self-report questionnaires administered at specific time points.

RESULTS: Patients who reported at least 30% improvement in self-reported pain from baseline to 6-month follow-up were considered responders (N=31). Pain responders and non-responders did not differ significantly at baseline across any sleep continuity measures. At mid-treatment, only total sleep time (TST) predicted pain response via t-tests and logistic regression, whereas other measures of sleep continuity were non-significant. Recursive partitioning analyses identified a minimum cut-point of 382 minutes of TST achieved at mid-treatment in order to best predict pain improvements 6-month post treatment. Actigraphy results followed the same pattern as daily diary based results.

CONCLUSIONS: Clinically significant pain reductions in response to both CBT-I and BD were optimally predicted by achieving approximately 6.5 hours sleep duration by mid-treatment. Thus, tailoring interventions to increase total sleep time early in treatment may be an effective strategy to promote long-term pain reductions. More comprehensive research on components of behavioral sleep medicine treatments that contribute to pain response is warranted.