Objectively Measured Sleep Disorders in Rheumatoid Arthritis and Their Association With Disease Activity.

Abstract

Poor self-reported sleep is common in rheumatoid arthritis (RA), but studies using objective sleep measures are rare. We report the prevalence of objectively measured sleep characteristics in individuals with RA and their association with clinical measures of RA disease activity. Data were from a longitudinal study with four measurement periods at 6-month intervals. Sleep data were collected by actigraphy over 7 days at each period. Primary actigraphy sleep variables were sleep efficiency (SE; time asleep/time in bed), time awake after sleep onset (WASO), and total sleep time. At baseline, WatchPAT devices were also used for two nights to assess presence of sleep-disordered breathing (SDB; primarily obstructive sleep apnea (OSA) indicated by the apnea-hypopnea index [AHI]). Disease activity measures (Clinical Disease Activity Index [CDAI], Disease Activity Score [DAS] 28 joints, DAS C-reactive protein [CRP], and DAS erythrocyte sedimentation rate) were completed by rheumatologists before each sleep-monitoring period. Prevalence of sleep problems was estimated, and associations of sleep characteristics with RA disease activity were analyzed with regression models. Of 133 individuals enrolled, 116 had sufficient actigraph wear time for scoring at baseline, and 63 completed WatchPAT monitoring. More than 40% of the cohort had poor SE (<85%) at all measurement periods completed. More than half with WatchPAT assessments had moderate to severe OSA (AHI ≥ 15). Lower SE and higher WASO were associated with greater disease activity across all measures. AHI was associated with CDAI and DAS-CRP. Objectively measured sleep problems were frequent and associated with RA disease activity. Given high rates of sleep disorders and their significant negative health effects, greater attention to sleep disorders among individuals with RA is warranted.