Introduction: Sleep disturbance is often comorbid with chronic pain disorders, with emerging evidence suggesting a stronger effect of sleep disturbance on pain than vice versa; however, few studies have evaluated the long-term associations between sleep disturbance and pain. This study was to examine the associations of sleep disturbance with knee pain severity, number of painful sites (NPS) and persistent pain in a 10.7-year cohort study.
Methods: A total of 1099 community-dwelling older adults (age mean ± SD, 63 ± 7.5 years; 51% female) were recruited and followed up at 2.6, 5.1 and 10.7 years later. Data on demographics, body mass index, physical activity and comorbidities were collected. At each time point, sleep disturbance, knee pain severity and NPS were assessed by using questionnaires. Multisite pain (MSP) was defined as NPS ≥ 2. Persistent knee pain or MSP was defined as having knee pain or MSP at all time points, respectively. Multivariable mixed-effects models and log-binomial regression were applied.
Results: In multivariable analyses, sleep disturbance was associated with greater knee pain severity (β 0.91/unit, 95% CI 0.70-1.11) and more NPS [(relative risk (RR) 1.10/unit, 95% CI 1.07-1.14] in a dose-response manner. Persistent sleep disturbance was associated with persistent knee pain (RR 1.90, 1.26-2.87) and MSP (RR 1.29, 1.07-1.56). Persistent knee pain and MSP were also associated with persistent sleep disturbance (knee pain: RR = 1.99; MSP: RR = 2.71, both P < 0.05).
Conclusions: Sleep disturbance was independently associated with greater pain severity and NPS in a dose-response manner. A reciprocal relationship between persistent sleep disturbance and persistent pain suggests treating either problem could help the other.
Keywords: Cohort study; Multisite pain; Musculoskeletal pain; Pain intensity; Sleep disturbance.