Prevalence and correlates of sleep disturbance in systemic sclerosis--results from the UCLA scleroderma quality of life study.

OBJECTIVE Rheumatologic disorders are associated with sleep disturbances. This study examines sleep disturbance correlates in patients with SSc. METHODS Participants are 180 SSc patients in an observational study. At baseline, patients completed the Medical Outcomes Study Sleep measure (MOS-Sleep scale). In addition, patients were administered other patient-reported outcome (PRO) measures including the 36-item short form (SF-36), HAQ disability index (HAQ-DI), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue), Center for Epidemiologic Studies Depression (CESD) scale and a University of California at Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract Questionnaire (UCLA SCTC GIT 2.0). Descriptive statistics were assessed for six scales of MOS-Sleep and the 9-item sleep problem index (SLP-9; a composite index). We computed Spearman's rank-order correlations between the MOS-Sleep scales and the HAQ-DI, FACIT-Fatigue, CESD, SSc-SCTC GIT 2.0 and SF-36 scales. In addition, we developed a regression model to assess predictors of SLP-9 scores. Covariates included demographics, physician variables of disease severity and patient-reported variables of worsening symptoms and the PRO measures. RESULTS SSc patients reported a mean (s.d.) of 7.1 (1.73) h of sleep a night. Patients reported worse scores on four of six scales (except for snoring and sleep quantity) compared with the US general population (P < 0.001). SLP-9 was correlated with worsening pain and dyspnoea over the past 1 month, reflux scale of the UCLA SCTC GIT 2.0, CESD and FACIT-Fatigue (ρ 0.26-0.56). In the stepwise multivariate regression model, the CESD, worsening dyspnoea and reflux scale were significantly associated with SLP-9 index. CONCLUSION Sleep disturbances are common in SSc and are associated with worsening dyspnoea, depressed mood and severity of reflux symptoms.