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.