Abstract
To evaluate the agreement of the 2-item (PHQ-2) and 8-item (PHQ-8) Patient Health Questionnaires compared to the PHQ-9 and clinical diagnosis for depression screening in Brazilian adults, and to examine associated sociodemographic and behavioral factors. We analyzed cross-sectional data from 148,733 participants in the 2013 and 2019 Brazilian National Health Surveys. ROC curve analyses identified optimal cutoffs for PHQ-8 and PHQ-2 against the PHQ-9 (≥ 10) and clinical indicators. Logistic regression and Ratio of Odds Ratios (ROR) compared associations across screening tools and self-reported diagnosis. The PHQ-8 (cutoff ≥ 10) showed near-perfect agreement with the PHQ-9 (AUC = 0.982). For the PHQ-2, a ≥ 3 cutoff optimized specificity (96.4%) and overall agreement (94.7%), with an AUC of 0.877. Optimal cutoffs against clinical indicators shifted lower (≥ 4 for PHQ-8; ≥ 1 for PHQ-2). Both brief versions identified associations profiles consistent with the PHQ-9 (e.g., higher odds in women, low-income individuals, and those with chronic diseases). However, ROR analyses revealed a significant healthcare gap: higher income and advancing age strongly predicted formal diagnosis, while Black/Brown populations and those with poor health were significantly underrepresented clinically compared to symptom screening. All scales showed strong reliability (α, ω > 0.85), including the PHQ-2 (r = 0.55; ρsb = 0.71). The PHQ-8 is a psychometrically equivalent alternative to the PHQ-9 in Brazil, and the PHQ-2 is a reliable, ultra-brief tool ideal for rapid, large-scale population screening. While these scales accurately capture symptom burden, the observed discrepancies with formal diagnosis highlight significant systemic barriers to mental healthcare access for vulnerable subgroups.
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Acknowledgements
The authors acknowledge the support of the Federal University of Ouro Preto (UFOP) and the Group for Research and Education in Nutrition and Collective Health (GPENSC) for their support and encouragement. We also extend our gratitude to the General Coordination of Chronic Non-Communicable Diseases (CGDNT) of the Department of Epidemiological Analysis and Surveillance of Non-Communicable Diseases (DAENT) of the Secretariat for Health and Environment Surveillance (SVSA) of the Ministry of Health (MS) for their collaboration in conducting this research and their valuable support. L.M.J. would like to thank the Brazilian National Council for Scientific and Technological Development (CNPq) and the Coordination for the Improvement of Higher Education Personnel (CAPES) for the postdoctoral fellowship (Call 26/2021).
Funding
This study was funded by the Brazilian Ministry of Health. Additional support was provided by the Brazilian Council for Scientific and Technological Development (CNPq, Distrito Federal, Brazil), the Coordination for the Improvement of Higher Education Personnel (CAPES, Brazil) and the Minas Gerais State Research Support Foundation (FAPEMIG, Minas Gerais, Brazil).
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Informed consent was obtained from all individual participants included in the study.
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The Brazilian National Health Survey (PNS) was approved by the National Commission for Ethics in Research (CONEP) (Report No. 10853812.7.0000.0008) in June 2013, in compliance with Resolution No. 466/2012 of the National Health Council (CNS). All participants provided informed consent. Participation was voluntary, with guarantees of anonymity and the right to withdraw at any time.
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de Oliveira, L.R.F., Barbosa, B.C.R., Vidigal, M.C.A. et al. Agreement among brief patient health questionnaire (PHQ) versions for measuring symptoms of depression in the Brazilian national health survey (PNS). Sci Rep (2026). https://doi.org/10.1038/s41598-026-51712-7
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DOI: https://doi.org/10.1038/s41598-026-51712-7
