Prevalence and correlates of comorbid obstructive sleep apnea and restless legs syndrome in a population-based study from Benin, West Africa

Purpose: Comorbid restless legs syndrome (RLS) and obstructive sleep apnea (OSA) -(COROSA)- is poorly characterized in African populations. We estimated its prevalence and correlates in a population-based sample in Benin. Methods: This was a cross-sectional analysis of 1,810 adults aged [≥]25 years from the Benin Society and Sleep (BeSAS) study. RLS was defined by International RLS Study Group criteria and OSA by an apnea-hypopnea index [≥]5 events/h on home respiratory polygraphy; COROSA required both. Correlates were assessed by multivariable logistic regression; multinomial models compared COROSA with OSA only, RLS only, and neither disorder. An exploratory analysis examined hypertension across eight mutually exclusive sleep-disorder groups, including comorbid insomnia, RLS and OSA (COMIROSA). Results: COROSA prevalence was 3.5% (95% CI 2.7-4.4). Independent correlates were age 40-59 years (aOR 2.91, 95% CI 1.38-6.73), age [≥]60 years (aOR 3.76, 1.61-9.35), rural residence (aOR 10.54, 4.94-25.43), overweight (aOR 2.29, 95% CI: 1.16-4.49), obesity (aOR 3.83, 95% CI: 1.75-8.31), and insomnia (aOR 2.49, 1.37-4.50). Relative to OSA only, COROSA was associated with hypertension and insomnia; relative to RLS only, obesity was the main distinguishing factor. Hypertension was associated with COROSA and COMIROSA, with a larger estimate for COMIROSA (aOR 4.03 vs 2.64). Conclusion: COROSA affected 3.5% of adults in Benin and co-occurred with obesity, hypertension and insomnia. Screening for overlapping sleep disorders may improve identification of high-risk individuals. COMIROSA remains a hypothesis requiring validation in larger longitudinal studies.