The World Health Organization Somatoform Disorders Schedule. A preliminary report on design and reliability

The World Health Organization (WHO) Somatoform Disorders Schedule (SDS) is a highly standardized instrument for the assessment of somatoform disorders according to the tenth revision of the International Classification of Diseases (ICD-10) and the fourth edition of the Diagnostic and Statistical Manual (DSM-IV). The SDS was produced in the framework of the WHO International Study of Somatoform Disorders and tested for its reliability in Brazil, India, Italy, the USA and Zimbabwe. A sample of 180 patients from general psychiatry, primary care and general medical settings were interviewed with the SDS within a three-day interval by non-clinician and clinician interviewers. The agreement between the two interviews was tested using the intraclass correlation coefficients (ICC) and kappa statistic. The test-retest reliability of the SDS was found to be very good (the ICC for all the centres was 0.76; overall kappa value for SDS questions was 0.58; one-third of SDS questions had a kappa value of 0.60 or higher). The field test results of the SDS indicated that the instrument may be administered in larger studies by non-clinician interviewers without compromising the ability to document the prevalence of somatoform disorders in different cultures.