Abstract
Background: Poststroke depression affects about 30% of stroke survivors within five years. Timely diagnosis and management facilitate motor recovery and improve independence. The Patient Health Questionnaire-9 (PHQ-9) is one of the good screening tools for poststroke depression. High validity and reliability of the PHQ-9 is clinically essential.
Methods: The objectives of the study were to determine the criterion validity and reliability of the PHQ-9 (Thai version) in screening for poststroke depression by comparing with a psychiatric interview as the gold standard. First-ever stroke patients aged ≥ 45 years with a stroke duration 2 weeks–2 years were administered the PHQ-9. The gold standard was a psychiatric interview for major depression. Diagnosis of major depression according to PHQ-9 can be categorical algorithm based and summed score based. The validity of these 2 ways of diagnosis and reliability analyses, and a receiver operating characteristic curve analysis, were performed.
Results: Enrolled were 115 stroke patients (mean age, 64 + 10 years). The mean PHQ-9 score was 5.2 + 4.8. Using DSM-5 criteria, 23 patients (20%) were diagnosed with depressive disorder. The PHQ-9 had satisfactory internal consistency (Cronbach’s alpha, 0.78). The categorical algorithm of the PHQ-9 had low sensitivity (0.52) but very high specificity (0.94) and positive likelihood ratio (9.6). Used as a continuous measure, an optimal cut-off score of ≥ six revealed a sensitivity of 0.87, specificity of 0.75, positive predictive value of 0.46, negative predictive value of 0.95, and positive likelihood ratio of 3.5. The area under the curve was 0.87 (95% CI, 0.78–0.96).
Conclusions: The PHQ-9 has acceptable psychometric properties for screening for poststroke depression, with a recommended cut-off score of ≥ six.
The Validity and Reliability of the Patient Health Questionnaire-9 in Screening for Poststroke Depression
