A systematic review of the psychometric properties of the Patient Health Questionnaire-4 (PHQ-4) in clinical and non-clinical populations

The Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief instrument that measures depressive and anxiety symptoms. Although it has been frequently used in the last 15 years, no research has systematically reviewed its psychometric properties. This systematic review summarized, for the first time, the available published evidence on the psychometric properties of the PHQ-4. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was registered in the Prospective Register of Systematics Reviews (PROSPERO), under the identification code: CRD42022381809. The search strategy was applied in Medline, PsycINFO, Web of Science, and SCOPUS from 2009 (year of publication) to 2023 (present). Two independent reviewers performed screening, data extraction, and methodological quality assessment of the studies. The data was reported through a narrative synthesis. In total, 26 studies involving 93,466 participants from 19 countries, with clinical and non-clinical samples, were included. The two-factor structure was the most frequent, being invariant according to gender, age, geographic location, income, educational level, and language. The internal consistency was adequate for distress (α from .72 to .88), as well as for depression (α from .65 to .81) and anxiety (α from .74 to .84). The temporal stability of the instrument was verified through test-retest reliability, reporting an acceptable connection between both measures. Correlations with related measures were significant and in the expected direction. The PHQ-4 is a reliable and valid instrument for screening depressive and anxiety symptoms, both for the clinical and non-clinical population. Due to the brevity of its administration, the PHQ-4 could be a clinical tool that contributes to optimizing health resources.