Diagnostic Interview for Genetic Studies (DIGS): validity, inter-rater and test-retest reliability of the Thai version (Th-DIGS)

Objective: to study the diagnostic validity, inter-rater reliability, and test-retest reliability of the th-digs. methods: the digs was translated into thai. the accuracy and understandability was assured by back translation, consensus review and a pilot interview. the studied subjects were recruited from three major referral mental health centers in central thailand. we recruited a total of 170 subjects with clinical psychiatric diagnoses and 33 controls. the referral psychiatric diagnoses were schizophrenia (n=33), major depressive disorder (n=31), bipolar i disorder (n=32), alcohol dependence (n=39), amphetamine dependence (n=35). to study validity and inter-rater reliability, we interviewed the subjects with the th-digs by a trained interviewer in the presence of a co-rater who simultaneously completed the th-digs. approximately four weeks later, we re-interviewed the subjects using the th-digs by a third independent interviewer to study the test-retest reliability. we then calculated the diagnosis concurrent validity, inter-rater and test-retest reliability of the th-digs. results: the overall kappa of concurrent validity was 0.82 with 93.6% sensitivity and 95.0% specificity. the overall kappa coefficients of inter-rater reliability and the test-retest reliability were 0.89 and 0.78, respectively. the excellent validity and reliability are robust to most diagnoses. the concurrent validity of alcohol dependence and the test-retest reliability of controls, major depressive disorder and alcohol dependence were in fair-to-good range. moreover, the th-digs also reliably discriminated normal controls from subjects with psychiatric disorders. conclusion: the th-digs has been developed. the study in thai subjects demonstrated a good-toexcellent validity, inter-rater and test-retest reliability. this indicates that the th-digs is a highly valid and reliable instrument for use in psychiatric studies, and studies of a variety of psychiatric disorders including alcohol dependence and amphetamine dependence