Exploring the Unidimensionality of the GAD-7 for South African First Responders: Evidence from Multiple Psychometric Approaches

Generalized Anxiety Disorder (GAD) is a prevalent mental health condition and the GAD-7 is widely used as a screening tool and measure of GAD severity. However, research has yielded conflicting findings regarding the factor structure of the instrument, with some studies supporting a unidimensional interpretation while others suggest a two-factor solution. These inconsistencies highlight the importance of validating the GAD-7 across diverse populations. This study aimed to assess the psychometric properties and factor structure of the GAD-7 among South African first responders (n = 429). Participants completed a demographic questionnaire along with the GAD-7, the Patient Health Questionnaire, the Post-Traumatic Stress Disorder Checklist, and subscales from the Maslach Burnout Inventory, namely Emotional Exhaustion and Depersonalization. The dimensionality of the GAD-7 was examined using Mokken Scale Analysis (MSA), parallel analysis, and Confirmatory Factor Analysis (CFA) with a Schmid-Leiman transformation. Results supported the unidimensionality of the GAD-7. MSA indicated that all items were loaded onto a single scale, with strong inter-item correlations and a high H-coefficient. The parallel analysis confirmed that only one factor was necessary, and the Schmid-Leiman transformation extracted a general factor accounting for 84% of the item variance. Furthermore, the reliability of the GAD-7 was excellent, with alpha and omega coefficients exceeding 0.90, indicating high internal consistency. The strong reliability and validity of the GAD-7 in this study reinforce its utility as a reliable tool for assessing generalized anxiety in a non-clinical setting.