The Patient Health Questionnaire-9 as a Screening Tool for Depression in Individuals with Type 2 Diabetes Mellitus: The Maastricht Study.

OBJECTIVES: To assess the psychometric properties and identify the best cutoff value of the Patient Health Questionnaire-9 (PHQ-9) for depression screening in individuals with type 2 diabetes mellitus (T2DM).

DESIGN: Observational population-based cohort study.

SETTING: The Maastricht Study.

PARTICIPANTS: Individuals with and without T2DM (mean age 58.6 ± 8.1, 44.6% male) according to an oral glucose tolerance test (N = 2,997).

MEASUREMENTS: Depressive disorder and depressive symptoms were measured using the Mini-International Neuropsychiatric Interview (MINI) as the reference and the PHQ-9. Cronbach alpha, Cohen's kappa and receiver operating characteristic (ROC) analyses were used. Differences in factorial structure between participants with and without T2DM were tested using multigroup confirmatory factor analysis.

RESULTS: Based on the traditional PHQ-9 cutoff value, 133 (4.4%) participants had depressive symptoms (PHQ-9 score ≥10). Internal consistency of the PHQ-9 was good (Cronbach α = 0.87 with T2DM, 0.82 without T2DM), the kappa of agreement between the PHQ-9 and the MINI was moderate (0.40 with T2DM, 0.43 without T2DM). Area under the ROC curve for the PHQ-9 was 0.87 in participants with T2DM and 0.88 in those without. A PHQ-9 cutoff score of 5 provided the best sensitivity (92.3%), with acceptable specificity (70.4%), for T2DM, similar to sensitivity and specificity in individuals without T2DM. Factor analysis suggested a similar two-factor structure in both groups (affective and somatic symptoms).

CONCLUSION: Patient Health Questionnaire-9 performs well as a screening tool for depressive symptoms in individuals with and without T2DM based on the cutoff value of 5, indicating that the PHQ-9 can be used in two-stage screening in primary care to select individuals with T2DM for further psychological evaluation.