Depression and Addiction as Key Predictors of Suicidal Ideation Among Medical and Nursing Students: An Integrated Analysis Using Regression, ROC, and Structural Equation Modeling

Abstract

Background: Suicidal ideation among medical and nursing students is a clinically important concern for student mental health. Recent regional evidence from medical sciences students in Iran indicates that suicidal ideation is associated with mental health problems, while the broader student literature links suicidal thoughts to depression, hopelessness, and behavioral vulnerability. Objectives: This study examined depression, addiction tendency, and selected sociodemographic correlates of suicidal ideation among Iranian medical and nursing undergraduates. Methods: We conducted a cross-sectional study among undergraduate medical and nursing students at Zahedan University of Medical Sciences. Using a two-stage stratified cluster sampling method, we invited 600 eligible students; 20 declined participation and 18 returned incomplete questionnaires, yielding 562 analyzable responses. We assessed suicidal ideation (BSSI), depression (BDI-II), and addiction tendency (ZAPS) using standardized Persian instruments. We estimated associations using multiple regression, evaluated discrimination using ROC/AUC analysis, and examined hypothesized direct and indirect pathways using structural equation modeling (SEM). We also assessed regression assumptions and multicollinearity. Results: Depression showed the strongest cross-sectional association with suicidal ideation, whereas addiction tendency showed a smaller independent association. The multivariable model explained more than half of the variance in suicidal ideation. The logistic model demonstrated high apparent discrimination in the same cross-sectional sample (AUC = 0.92). SEM supported a direct association between depression and suicidal ideation, as well as a statistically significant indirect pathway via addiction tendency (standardized indirect effect = 0.077; 95% bootstrap CI: 0.033 to 0.124). Conclusions: In this single-site cross-sectional sample, depression was the primary correlate of suicidal ideation, whereas addiction tendency provided independent explanatory information and contributed to a statistically significant indirect pathway. Because the study was cross-sectional and the model was not externally validated, the indirect pathway should not be interpreted causally, and the high AUC should be interpreted with caution. Prospective multicenter studies are needed before this model is used to guide screening or implementation decisions.