Preliminary Study of the Thai Version of the Scale for the Assessment of Negative Symptoms (SANS-Thai)

OBJECTIVES: The study aimed to evaluate content validity, convergent validity, internal consistency and test-retest reliability of the Thai version of the Scale for the Assessment of Negative Symptoms (SANS-Thai). METHODS: The content validity of the SANS-Thai was assessed using four experts. The average-content validity index and item level content validity index were analyzed. The SANS-Thai and the Thai versions of the Addenbrooke’s Cognitive Examination (ACE) were administered to 40 people with schizophrenia to examine convergent validity and internal consistency. Twenty participants took the second SANS-Thai assessment within four weeks to evaluate test-retest reliability. RESULTS: The results demonstrated that the SANS-Thai has excellent content validity with the average-content validity index of 0.94. The majority of the item level content validity index range from 0.75 to 1. The global and total SANS-Thai score moderately correlated with the ACE with the correlation coefficient of -0.48 (p = 0.002) and -0.49 (p=0.001), respectively. Internal consistency by the Cronbach alpha coefficient was 0.95. Test-retest reliabilities by intraclass correlation were 0.91 (p<0.001) for global SANS-Thai and 0.9 (p<0.001) for total SANS-Thai. The Bland-Altman plot demonstrated that only 5% of the participants fell outside the limits of agreement for both global SANS and total SANS scores. CONCLUSION: The SANS-Thai appears to be a valid and reliable measure of negative symptoms in schizophrenia and could be useful for patient care and research studies.