Clinical utility and psychometric validity of the International Adjustment Disorder Questionnaire in a sample of South African working adults

Background: Adjustment disorder (AjD) is a significant yet often underdiagnosed condition in workplace mental health. The International Adjustment Disorder Questionnaire (IADQ) has shown promise as a screening tool, but its clinical utility within South African (SA) occupational settings remains unexplored. Aim: To assess the psychometric validity and clinical utility of the IADQ in an educated SA workplace population. Setting: The research was conducted across various occupational sectors in South Africa. Methods: A cross-sectional survey included the IADQ alongside validated measures of depression, anxiety, post-traumatic stress disorder and psychological resilience. Confirmatory factor analysis assessed structural validity, while performance of the IADQ algorithm was evaluated against clinical interviews. A grey zone approach was considered to refine screening thresholds. Results: Adjustment disorder point prevalence was 4.3% in this sample. Confirmatory factor analysis supported the two-factor model of AjD symptoms, with measurement invariance observed across gender and language groups. The IADQ algorithm demonstrated good diagnostic accuracy for screening purposes, with sensitivity and specificity values exceeding 0.95. Psychological resilience was associated with lower odds of AjD. Conclusion: The IADQ demonstrated good psychometric properties and clinical utility for comparable workplace mental health screening. The grey zone approach may offer a practical framework for graduated triage in resource-limited settings. Contribution: Our study supported the global applicability of the two-factor AjD symptom model, provided updated AjD prevalence rates for a SA workplace sample, and considered a refined screening method for use in occupational mental health services.