Abstract
BackgroundMost depression screening tools in Thailand are lengthy. The long process makes them impractical for routine use in primary care. This study aims to examine the reliability and validity of a Thai version Patient Health Questionnaire (PHQ-9) as a screening tool for major depression in primary care patients.MethodsThe English language PHQ-9 was translated into Thai. The process involved back-translation, cross-cultural adaptation, field testing of the pre-final version, as well as final adjustments. The PHQ-9 was then administered among 1,000 patients in family practice clinic. Of these 1,000 patients, 300 were further assessed by the Thai version of the Mini International Neuropsychiatric Interview (MINI) and the Thai version of the Hamilton Rating Scale for Depression (HAM-D). These tools served as gold-standards for diagnosing depression and for assessing symptom severity, respectively. In the assessment, reliability and validity analyses, and receiver operating characteristic curve analysis were performed.ResultsComplete data were obtained from 924 participants and 279 interviewed respondents. The mean age of the participants was 45.0 years (SD = 14.3) and 73.7% of them were females. The mean PHQ-9 score was 4.93 (SD = 3.75). The Thai version of the PHQ-9 had satisfactory internal consistency (Cronbach's alpha = 0.79) and showed moderate convergent validity with the HAM-D (r = 0.56; P < 0.001). The categorical algorithm of the PHQ-9 had low sensitivity (0.53) but very high specificity (0.98) and positive likelihood ratio (27.37). Used as a continuous measure, the optimal cut-off score of PHQ-9 ≥ 9 revealed a sensitivity of 0.84, specificity of 0.77, positive predictive value (PPV) of 0.21, negative predictive value (NPV) of 0.99, and positive likelihood ratio of 3.71. The area under the curve (AUC) in this study was 0.89 (SD = 0.05, 95% CI 0.85 to 0.92).ConclusionThe Thai version of the PHQ-9 has acceptable psychometric properties for screening for major depression in general practice with a recommended cut-off score of nine or greater.
Highlights
Most depression screening tools in Thailand are lengthy
In Thailand, most patients with mental disorders are often treated by general practitioners (GPs) because the number of psychiatrists in the country is still small
We excluded from the study 76 of the 1,000 respondents who participated in the study and 21 of the 300 respondents who were further assessed by the Mini International Neuropsychiatric Interview (MINI) and the HAMD due to incomplete data
Summary
Most depression screening tools in Thailand are lengthy. The long process makes them impractical for routine use in primary care. This study aims to examine the reliability and validity of a Thai version Patient Health Questionnaire (PHQ-9) as a screening tool for major depression in primary care patients. During the past two decades, health care professionals have made major progress towards the treatment of depressive disorders. In Thailand, most patients with mental disorders are often treated by general practitioners (GPs) because the number of psychiatrists in the country is still small. People are reluctant to seek help from a psychiatrist, because of existing prejudices against psychiatric disorders. This has been reported in studies from several countries [3,4,5]. GPs in Thailand, as in many other countries, play an important role in taking care of patients with mental heath problems
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