Global inequalities in common mental disorders: Understanding the predictors of lifetime prevalence, treatment utilisation and perceived helpfulness across 111 countries

Background Socio-economic inequalities in common mental disorders (CMDs) such as lifetime prevalence, treatment utilisation, and perceived treatment helpfulness have been documented in various settings. However, whether these inequalities are present globally (in both HICs and LMICs) and what factors explain between-country variation is unclear because of inadequate cross-national data. We therefore examine this question using a recently published global, individual-level survey data. Methods This study uses a nationally representative individual-level survey dataset (Wellcome Global Monitor 2020), in 111 countries (N= 117,088) to test if socio-economic factors (household income quintile, education), psycho-social factors (local stigma perception, trust in health professionals) and country-level factors (GDP, Gini, health expenditure) predict (1) CMD lifetime prevalence, (2) utilisation and (3) perceived helpfulness of talking to a mental health professional and taking prescribed medication. Multi-level logistic regression models were used. Findings Across both HICs and LMICs, individuals in higher household quintiles are less likely to experience anxiety or depression (OR=0.90 for each increase in income quintile, 95% CI[0.89–0.91]), more likely to talk to a mental health professional (OR=1.05[1.03–1.07]) and more likely to perceive this treatment as ‘very helpful’ (OR=1.06[1.03–1.09]). Income is not, however, linked to utilisation (OR=0.98[0.97–1.01]) and helpfulness of taking prescribed medication (OR=1.02[0.99–1.05]). Perceived stigma reduces mental health professional utilisation (OR=0.93[0.90–0.97]) and helpfulness (OR=0.76[0.72–0.81]), while trust in health practitioners increases both utilisation (OR=1.10[1.06–1.14]) and helpfulness (OR=1.32[1.24–1.40]). Country-level health expenditure is related to higher mental health professional utilisation (OR=1.11[1.04–1.19]. Interpretation This analysis reveals a global ‘triple inequality effect’, whereby the disadvantages of lower SES individuals persist in each outcome (lifetime prevalence, treatment utilisation and helpfulness). But these inequalities are moderated by background factors such as stigma and trust in health professionals, and depend on the type of treatment. These findings suggest that addressing inequalities in CMDs cannot focus on only one of these inequalities alone nor can efforts ignore the social context in which they are embedded.