Sleep quality and predictors of optimal sleep in patients with rheumatoid arthritis: data from a recent-onset cohort.

Objectives: Sleep disorders are part of the symptomatology of rheumatoid arthritis (RA) patients and are related to disease characteristics and comorbidities. The study describes sleep quality among RA patients and identifies predictors of optimal sleep.

Methods: Patients whose data were analysed were identified from the recent-onset RA cohort initiated in 2004. In 2010, the Medical Outcome Study Sleep Scale (MOS-SS) was incorporated into the patients' assessments. Up to December 2019, the cohort comprised 187 patients with at least one MOS-SS application (in 78 patients at cohort entry) and six months of outcomes behaviour (cumulative) previous to the MOS-SS application: DAS28-ESR, pain-VAS, fatigue, HAQ-DI, SF-36, treatment (corticosteroids, DMARDs/patient and adherence), Charlson score, and major depressive episodes. A trained data abstractor retrospectively reviewed their charts. Multiple logistic regression analysis estimated odds ratios (95% confidence interval) to define baseline and cumulative variables predictive of optimal sleep (dichotomised variable derived from the quantity of sleep dimension of the MOS-SS).

Results: At the first MOS-SS application, patients were primarily middle-aged women with short disease duration and low disease activity. They scored higher on the "snoring" and "sleep non-adequacy" MOS-SS dimensions. There were 96 patients (51.3%) with optimal sleep. Lower baseline BMI, better baseline fatigue score, longer follow-up at the clinic, and better SF-36 physical summary score were predictors of optimal sleep (mental summary score also remained in the model when switched to the physical summary score).

Conclusions: Optimal sleep is achieved by half of the RA patients and predicted by BMI, patient-reported outcomes, and follow-up.