RESUMEN
A short questionnaire, selecting a few items from an existing general health questionnaire is presented. A short screening questionnaire for psychiatric screening in primary care was developed. The Thai version of GHQ-60 was chosen as the source of items to be selected. A technique called search partition analysis (SPAN) was applied to the data derived from 100 patients attending a mobile community health service unit. The best subset of five items in a form of Boolean expression {(q49 > 1) or (q46 > 1) or (q55 > 0 and q1 > 1) or (q55 > 0 and q44 > 1)} was obtained. All of the validity measures except sensitivity are higher than those of the 12- and 60-item forms. The decision rule has potential for detecting psychiatric morbidity in primary care.