A trans-cultural comparison of four psychiatric case-finding instruments in a Welsh community

Background: Case-finding instruments have been developed for different purposes and in different cultural settings. Four instruments designed to detect psychiatric morbidity in community-based populations were studied in order to compare the performance of instruments from differing sources in a common setting. Methods: The study was undertaken in a Welsh primary care setting. The Revised Clinical Interview Schedule (CIS-R) was used to define caseness. The instruments studied were the General Health Questionnaire (GHQ), the Mental Health Index (MHI), the Self Reporting Questionnaire (SRQ), and the Shona Symptom Questionnaire (SSQ). Performance was assessed by standard test indices, kappa values, and receiver operating curve analysis. The content of the four instruments was also compared. Results: Sixty-nine adults completed the study. The prevalence of CIS-R caseness in this sample was 45%. No significant differences in case-recognition were found and all instruments had misclassification rates of 10% or less. The instruments showed wide variation in content. Half the items were unique to a single instrument and only three items (sleep, unhappiness and decision making) were shared by three instruments. The most frequent symptom within the total sample, and among cases, was the Zimbabwean concept of 'thinking too much'. Conclusions: Etic instruments (SRQ and SSQ) performed as well as emic ones (GHQ and MHI) in this setting, despite the wide variation in instrument structure.