Valid group comparisons can be made with the Patient Health Questionnaire (PHQ-9): A measurement invariance study across groups by demographic characteristics.
David Villarreal-ZegarraAnthony Copez-LonzoyAntonio Bernabé-OrtizG J Melendez-TorresJuan Carlos Bazo-AlvarezPublished in: PloS one (2019)
The evidence presents support for the one-dimensional model and measurement invariance of the PHQ-9 measure, allowing for reliable comparisons between sex, age groups, education level, socioeconomic status, marital status, and residence area, and recommends its use within the Peruvian population.