Objective: To determine the validity and reliability of the Thai version of the WHO Psychotic Disorders Sections of the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) Version 2.1
Material and method: The SCAN interview version 2.1 Psychotic Symptoms Sections (Section 16: Perceptual disorders other than hallucinations, Section 17: Hallucinations, Section 18: Experiences of thought disorder and replacement of will, and Section 19: Delusions) were translated into Thai. The content validity of the translation was established by comparing a back-translation of the Thai version to the English original. Whenever inconsistencies were encountered, the Thai version was adapted to convey the meaning of the original. The revised Thai version was then field-tested in 4 regions (Suanprung Psychiatric Hospital, Jitavejkhonkaen Hospital, Srithanya Hospital and Suansaranrom Psychiatric Hospital, each place comprised 20 volunteers ) for comprehensibility of the relatively technical language. Between October 2004 and July 2006, thirty persons were recruited for the reliability study (16 males; 14 females). Sixteen persons were schizophrenic patients (9 males; 7 females) and 14 (7 males; 7 females) were normal persons or nonpsychotic psychiatric patients. Education and occupations varied widely. The subjects were interviewed by a psychiatrist competent in using the Thai version of SCAN and these interviews were recorded on video for later re-rating.
Results: Based on the response from Thai subjects and consultations with competent psychiatrists, content validity was established The time taken to interview a schizophrenic patient averaged 140.2 +/- 36.0 minutes (range, 75-193) vs. 81.9 +/- 25.9 minutes (range, 48-124) for a comparison subject. The respective mean +/- SD of inter-rater reliability (kappa) of Section 16, 17, 18 and 19 was 0.66 +/- 0.17, 0.71 +/- 0.16, 0. 70 +/- 0.22 and 0.64 +/- 0.23. Some items in some sections had 100 percent agreement between raters. The respective intra-rater reliability was 0.65 +/- 0. 11, 0. 74 +/- 0.17, 0.86 +/- 0.17 and 0.80 +/- 0.18. Some sections had items with 100 percent agreement from the same rater even when rated 2 weeks apart. More than half of the items in each section had kappa values, both inter-rater and intra-rater, at least in substantial level.
Conclusion: The Thai version of the Psychotic Disorders Sections of SCAN version 2.1 proved to be a valid and reliable tool for assessing psychotic symptoms among Thais.