Clinical correlates of sleep problems in systemic sclerosis: the prominent role of pain.

OBJECTIVE Problems with sleep are common in patients with SSc and impact daily function. Little research, however, has examined factors associated with sleep disruption in SSc. Therefore, the objective of this study was to investigate socio-demographic and medical factors associated with sleep disruption in SSc. METHODS Cross-sectional study of 70 patients from one Canadian Scleroderma Research Group site who were assessed with a 100-mm sleep disruption visual analogue scale (VAS). Patients also completed measures of pain and depressive symptoms and underwent clinical histories and medical examinations. Pearson's correlations were used to assess bivariate association of socio-demographic and medical variables with sleep VAS scores. Multivariable associations of socio-demographic (Step 1) and medical (Step 2) variables with sleep VAS scores were assessed using hierarchical multiple linear regression. RESULTS The mean (s.d.) sleep disruption VAS score was 38.5 (29.9). In bivariate analyses, sleep disruption was associated with marital status (r = -0.24, P = 0.042), smoking (r = 0.27, P = 0.025), gastrointestinal symptoms (r = 0.27, P = 0.023), breathing problems (r = 0.31, P = 0.009), pain (r = 0.53, P < 0.001) and symptoms of depression (r = 0.34, P = 0.004). In multivariate analysis, only marital status (standardized β = -0.24, P = 0.049) and pain (standardized β = 0.50, P < 0.001) were significantly associated with sleep disruption. CONCLUSION Sleep disruption scores were as high in SSc as in RA and higher than in the general population. Pain was robustly associated with sleep disruption. Additional research is needed on sleep in SSc so that well-informed sleep interventions can be developed and tested.