Validation of the PHQ-4 as a unidimensional screener in 191,519 Australian children and adolescents

OBJECTIVE: A promising short-form tool for screening mental health in children is the Patient Health Questionnaire (PHQ-4) which contains two items each assessing anxiety and depression. Despite its emerging use, the construct validity of the PHQ-4 remains to be fully established in children and especially in pre-adolescent children as does its convergent validity. METHOD: Children completed an online survey containing demographic and PHQ-4 items during school time in 2024 to 88,587 pre-adolescent (7-11y: 48% F, 49% M, 3% Minority Gender (MG)), 66,561 early adolescent (12-14y: 50% F, 47% M, 3% MG), and 36,731 late adolescent (15-18y: 53%F, 44% M, 3% MG) Australian children. In each age by gender identity groupings, dimensionality was tested using exploratory/confirmatory factor analyses (EFA/CFA) and exploratory graph analysis (EGA). Convergent validity was tested with Life Satisfaction Score and Child Hope Scale (CHS). RESULTS: PHQ-4 scores increased with age (Pre- < Early < Late Adolescent) and were higher in minority versus cisgender children (Male < Female < MG). EGA revealed that the PHQ-4 was unidimensional while CFA revealed a bidimensional model fit. PHQ-4 was moderately correlated with Life Satisfaction and CHS. CONCLUSIONS: Given the limitations of latent variable analysis when scale length is constrained, it is suggested that the PHQ-4 is best regarded as a brief unidimensional scale for screening general mental health in Australian children.