Update of the standardization of the Patient Health Questionnaire-4 (PHQ-4) in the general population

INTRODUCTION: PHQ-4, consisting of PHQ-2 and GAD-2, is a widely used screening instrument for depressive and anxiety symptoms in clinical settings and in epidemiological studies. In the present study we provide an update of normative data from the German general population.

METHODS: Data was collected in two randomly selected samples representative of the German general population in 2020 (N = 2503) and 2021 (N = 2519). We computed percentile norm values for the total sample (N = 5022) and for different age groups, stratified by gender.

RESULTS: Compared to previous data, only minor changes in normative values were observed. 95 %-thresholds were at a score of 6-7 for the PHQ-4, and 3-4 for PHQ-2 and GAD-2 respectively. The scales showed acceptable reliability with McDonald's omega of ω = 0.77 for PHQ-2, ω = 0.78 for GAD-2, and ω = 0.85 for PHQ-4.

LIMITATIONS: Lack of a diagnostic gold standard and suboptimal response proportion (44.2 %) are limitations of this study.

CONCLUSION: This update supports the continued use of PHQ-4 scales as reliable instruments. For psychometric application, the reported normative data for PHQ-2, GAD-2 and PHQ-4 facilitates more up-to-date comparisons.