Psychometric properties and symptom profiles of the PHQ-9 and DASS-21 among medical and non-medical university students: a cross-sectional study in Pakistan.

Authors

Taimoor Asghar, Ali Hassan, Ifrah Sahar, Muhammad Tahir, Bilal Shahid, Komal Komal

Published in

BMC psychology. Volume 14. Issue 1. Aug 12, 2026. Epub Aug 12, 2026.

Abstract

Depression is a leading cause of disability among university students. While medical students are often assumed to be at highest risk, cross-disciplinary comparisons in South Asia remain scarce. This study examined depressive symptom differences between medical and non-medical students in Pakistan and evaluated the concurrent psychometric performance of the PHQ-9 and DASS-21.
A cross-sectional survey of 602 undergraduate students (424 medical, 178 non-medical) was conducted at universities in Lahore, Pakistan. Measures included the PHQ-9 and DASS-21. Analyses comprised descriptive statistics, Wilcoxon rank-sum tests, multivariable linear regression (separate models for PHQ-9 and each DASS-21 domain), confirmatory factor analysis, item response theory using a graded response model, and symptom network analysis with stability testing.
Non-medical students had higher PHQ-9 scores than medical students (median 10.0 vs. 9.0). In adjusted models, non-medical students scored higher on PHQ-9 (β = -1.43, p = 0.004), DASS Depression (β = -1.82, p = 0.003), and DASS Anxiety (β = -2.31, p = 0.001); the DASS Stress difference was non-significant (β = -0.89, p = 0.089). Female gender predicted higher scores across all domains (all p < 0.001). Each additional hour of sleep was associated with lower PHQ-9 scores (β = -0.37, p = 0.010). Prior depression treatment was the strongest predictor (β = 4.15, p < 0.001). DASS-21 confirmatory factor analysis showed adequate fit (CFI = 0.954, TLI = 0.948, RMSEA = 0.052), but latent factor correlations were very high (Depression-Stress r = 0.939; Anxiety-Stress r = 0.949). Cronbach's α ranged 0.82-0.88 across scales. Item response theory indicated that self-worth, concentration, down, and appetite items showed the highest discrimination; interest (anhedonia) showed the lowest (a = 0.468). In network analysis, self-worth, concentration, and downheartedness were the most central nodes; stability coefficients ranged 0.31-0.44. Measurement invariance across discipline was supported. Model R² values were low (0.029-0.041).
Non-medical students reported higher depressive and anxiety symptoms than medical students in this Pakistani sample, although academic discipline explained only a small proportion of variance. Both instruments performed adequately, though the DASS-21's near-unity latent correlations may raise questions about subscale distinguishability in this population. Cognitive and self-worth symptoms emerged as the most informative for screening purposes. Campus mental health strategies should address the whole student population, with particular attention to female students and sleep health.

PMID:
42806369
Bibliographic data and abstract were imported from PubMed on 29 Sep 2026.

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