Mental Health Screening in Prison: Psychometric Evaluation of the PHQ-9 and GAD-7 Among Incarcerated Men in Mexico

BACKGROUND: Psychometric screening tools for persons in penitentiary centers (PPC) are key to assessing their mental health needs, given the shortage of both time and mental health personnel. Depression and anxiety are among the most prevalent mental health problems in PPC. Inadequate diagnosis can lead to increased symptom severity and even suicide. Therefore, validating instruments to assess depression and anxiety in PPC populations is essential to reduce the risk of misdiagnosis and its consequences. METHODS: A cross-sectional study was conducted to evaluate the reliability and validity of the Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder-7 (GAD-7) in 272 men (>18 years old) deprived of liberty in a penitentiary center in Mexico. Both exploratory and confirmatory factor analyses were performed. Concurrent and discriminant validity were assessed using the depression and anxiety scales of the International Statistical Classification of Diseases and Related Health Problems, Eleventh Revision (ICD-11) Primary Health Care (PHC). Receiver Operating Characteristic curves were plotted to determine the best cut-off points in both instruments. RESULTS: Both the PHQ-9 and GAD-7 showed items that were representative of their underlying constructs and supported the original one-factor structure, with satisfactory goodness-of-fit indices in both exploratory and confirmatory analyses. Both instruments exhibited good internal consistency in the sample of Mexican men incarcerated in penitentiary centers (α = 0.87 and α = 0.89, respectively). Furthermore, both scales showed strong correlations with the ICD-11 PHC depression and anxiety scales, along with adequate sensitivity, specificity, false positive, and false negative rates, resulting in a low misclassification rate. CONCLUSIONS: The PHQ-9 and GAD-7 can be used to briefly and reliably assess depression and anxiety among male PPC in Mexico City and in populations with similar institutional and sociodemographic conditions Given the specific characteristics of PPC populations across different countries, it remains necessary to continue testing these instruments in underrepresented populations to ensure the development of reliable and valid tools that help identify potentially confusing items and minimize diagnostic errors.