The effects of prevalence of inequalities in mental disorders between groups using Blinder– Oaxaca decomposition

BACKGROUND: The prevalence of inequalities in sociodemographic factors in some mental disorders (MDs) has been shown in previous reports. The aim of this study was to assess the main contributors that affected prevalence of inequalities in MDs between groups. MATERIALS AND METHODS: This was a cross-sectional study that was conducted on adults in 10 cities from Ilam province. We selected participants using cluster sampling; clusters were cities (n(1) = 10), geographical area (n(2) = 153), and households (n(3) = 382). Screening tools and clinical interview were applied through standardized and validated questionnaires, namely, GHQ-28 and DSM-IV-TR, respectively. Participants were divided into socioeconomic groups via principal composition analysis (PCA). Blinder–Oaxaca approach was applied to distinguish the gap in inequalities between groups. RESULTS: The prevalence of MDs in the advantage group was 22.6% and, in disadvantages was 35.6%. The concentration index (CI) of the MD prevalence rate was −0.013 (95% CI: −0.022, −0.004) which indicated that MDs were more common in the disadvantaged groups. The odds of MDs in advantaged people was 81% more compared to the disadvantaged group (OR: 1.81; 95% CI: 1.28, 2.57), also in females compared to males (1.60; 95% CI: 1.21, 2.24). Analysis of gap inequality between groups showed that the gap in prevalence rates of MDs between groups was 12%. CONCLUSION: This study revealed a socioeconomic inequality in MD rates in the adult population. Therefore, results of this study provide contributors in MDs inequality in order to control and reduce the prevalence of MDs in the community.