Characterization and determinants of sleep measured by self-report and wrist actigraphy in patients with interstitial lung disease

Abstract

PURPOSE The purpose of this study was to determine the association between sleep measurements by wrist actigraphy and patient self-report and assess the impact of physical activity and extrapulmonary symptoms on sleep quality in patients with fibrotic interstitial lung disease (ILD). METHODS Patients were recruited from specialized ILD clinics. Total sleep time, sleep efficiency, sleep latency and number of sleep disturbances were measured using the Pittsburgh Sleep Quality Index (PSQI) and an ActiGraph monitor worn on patients’ non-dominant wrist for seven consecutive days. Step counts were monitored over the same period using a waist monitor. Extrapulmonary symptoms were assessed with the Hospital Anxiety and Depression Scale and Brief Pain Inventory. Multivariable analyses were used to examine whether physical activity and extrapulmonary symptoms were determinants of sleep quality in fibrotic ILD. RESULTS A total of 111 patients were assessed (62% male, mean age 70 ± 9 years). Mean self-reported total sleep time was 494 ± 80mins/night. Median self-reported sleep efficiency and latency were 97% (94–98%) and 15 min (8–30 min), respectively. Poor sleep quality was reported in 61% of patients. Wrist monitors detected a mean total sleep time of 441 ± 72mins/night. Median sleep efficiency and latency measured by wrist monitors were 88% (83–91%) and 2 min (0–7 min), respectively. The PSQI was largely within limits of agreement in reference to the wrist monitor recordings. Higher pain severity was an independent predictor of reduced sleep efficiency, increased sleep latency and greater number of sleep disturbances measured by the PSQI on adjusted analyses. CONCLUSIONS The PSQI is generally in agreement with wrist actigraphy measurements. Pain is a determinant of sleep in fibrotic ILD.