Adult disability and mental/psychological illness in Somaliland socioeconomic inequalities and co-occurrence in the 2020 Somaliland Health and Demographic Survey

Disability is an important population-health concern, but adult-specific evidence on its distribution and socioeconomic patterning remains limited in Somaliland. This study estimated the prevalence and distribution of reported disability among adults in Somaliland and examined socioeconomic inequality, reported mental/psychological illness, and their co-occurrence. We conducted a cross-sectional secondary analysis of the 2020 Somaliland Health and Demographic Survey. The analysis included 14,579 adults aged [≥]18 years who were usual residents, had the disability module administered, and had a defined reported mental/psychological illness measure. Reported disability was defined as at least one positive response across seven disability domains: sight, hearing, speech, learning, mobility, self-care, and mental. Survey-weighted prevalence estimates and design-based comparisons were calculated. Survey-weighted logistic regression assessed associations with household wealth and other covariates. Socioeconomic inequality was assessed using a concentration index and the normalized Erreygers concentration index. Co-occurrence was evaluated by comparing observed joint prevalence with that expected under statistical independence and by survey-weighted logistic regression. The survey-weighted prevalence of any reported disability was 7.30% (95% CI 6.65-8.02). Sight was the most frequently reported domain (3.83%, 95% CI 3.19-4.59), followed by hearing (1.54%, 95% CI 1.20-1.97) and mobility (1.39%, 95% CI 1.14-1.70). Disability prevalence increased markedly with age, from 4.15% among adults aged 18-29 years to 23.96% among those aged [≥]60 years. The crude wealth pattern was non-monotonic and was not statistically detectable after adjustment for residence and region. The concentration index for reported disability was 0.0584 (SE 0.0284, p=0.0415). Reported mental/psychological illness had a weighted prevalence of 0.71% (95% CI 0.50-1.00). Both reported disability and reported mental/psychological illness occurred in 0.5032% of adults, compared with 0.05185% expected under statistical independence; the observed-to-expected ratio was 9.70 (95% CI 7.60-11.81). After adjustment for age group and sex, reported disability was strongly associated with reported mental/psychological illness (OR 42.99, 95% CI 18.45-100.18). Reported disability affected approximately one in fourteen adults in Somaliland and showed a marked age gradient and substantial geographic variation. The crude socioeconomic pattern was attenuated after adjustment for geographic context, while concentration analysis indicated modest marginal concentration toward higher wealth ranks. Reported mental/psychological illness was uncommon but co-occurred with reported disability more often than expected under independence. These findings provide an adult population baseline for Somaliland while highlighting the need to distinguish survey-reported disability from the separate mental/psychological illness construct and to interpret the findings within the limitations of cross-sectional, survey-reported measures.