Validation and cross-cultural adaptation of the depression Patient’s Health Questionnaire – 9 in the Romanian population of patients with Type 2 Diabetes Mellitus

Purpose: To validate and to evaluate the performance in depression screening of the Patient’s Health Questionnaire – 9 (PHQ-9) for Romanian patients with Type 2 Diabetes Mellitus (T2DM). Patients and methods: In a consecutive-case, population-based, non-interventional study design 107 hospitalized patients with T2DM were enrolled. The PHQ-9 was evaluated in regard to its acceptability, ceiling and floor effect, reproducibility, and test–retest performance. Its validity was tested by comparing it to the Beck depression scale, which is a validated tool for this patient population. Results: The PHQ-9 questionnaire had an excellent acceptability, having no non-responders for any of its questions and a median completion time of 3 mins and 12 s, a good reliability with a Cronbach’s α=0.897 [0.865–0.924] 95%CI, a good test–retest performance (Spearman’s rho =0.972; p<0.001 between two administrations of the test) without any ceiling or floor effect observed for the total score. At the same time, the score demonstrated a good validity when compared to a more complex and previously validated instrument like the Beck depression scale (Spearman’s rho =0.777; p<0.001). The limits of agreement (Bland-Altmann analysis) between the two measurements are 2.6 to −2.5 points. Conclusion: The PHQ-9 is a valid, useful instrument for depression screening in Romanian patients with T2DM.