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.

Brief summary

The coexistence of obstructive sleep apnea and restless legs syndrome is insufficiently documented in African populations despite the growing burden of sleep disorders in the region. This study provides the first population-based study estimate of comorbid obstructive sleep apnea and restless legs syndrome in sub-Saharan Africa.

Our findings suggest that individuals with both disorders represent a clinically important subgroup with substantial cardiometabolic burden and insomnia. They also raise the possibility of an even more complex overlap involving chronic insomnia, restless legs syndrome, and obstructive sleep apnea, which warrants validation in future studies.

These results support more integrated approaches to screening and management of these coexisting sleep disorders in resource-limited settings.