The validity and reliability of the Patient Health questionnaire 9 in screening poststroke depression

Abstract

Background: Poststroke depression occurred about 30% during the first five years after stroke. Timely diagnosis and management could facilitate motor recovery and improve independence. The Patient Health Questionnaire 9 (PHQ-9) is one of the best screening tools for poststroke depression. Since specific screening tool has not yet presented in Thailand, the validity and reliability of the PHQ-9 in stroke patients is clinically essential.

Objectives: To study the criterion validity and reliability of the PHQ-9 (Thai version) in screening poststroke depression by comparing to the psychiatric interview as the gold standard.

Material and Methods: First ever stroke patients age 45 years old and above who had duration of stroke from 2 weeks to 2 years were administered with PHQ-9. The gold standard was a psychiatric interview for major depressive disorder. The criterion validity and reliability analyses, and receiver operating characteristic curve analysis were performed.

Results: One hundred and fifteen stroke patients; with mean age 64+10 years old participated. The mean PHQ-9 score elicited was 5.2 + 4.8. According to the DSM-5 criteria; 23 of them (20%) were diagnosed as 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, the optimal cut-off score of PHQ-9 >/= 6 revealed a sensitivity of 0.87, specificity of 0.75, positive predictive value (PPV) of 0.46, negative predictive value (NPV) of 0.95, and positive likelihood ratio of 3.5. The area under the curve (AUC) in this study was 0.87 (95%CI=0.78,0.96).

Conclusion: The PHQ-9 has acceptable psychometric properties for screening for poststroke depression with a recommended cut-off score of six or greater.