Revisiting the developed versus developing country distinction in course and outcome in schizophrenia: Results from ISoS, the WHO collaborative followup project

This article examines the long-standing and provocative finding of a differ ential advantage in coarse and outcome for persons with schizophrenia livin g in "developing" countries, using results from the newly completed World H ealth Organization (WHO) collaborative project, the International Study of Schizophrenia (ISoS). The article addresses two questions: Has the differen tial survived the 13 years since it was last reported? If so, are the resul ts demonstrably not attributable to artifactual confounding? The analysis f ocuses on the 809 subjects who make up the combined incidence cohort of ISo S. These include members of the original treated incidence cohorts of two e arlier WHO studies (the Determinants of Outcome of Severe Mental Disorders and the Reduction of Disability Studies) as well as subjects drawn from two additional samples (Hong Kong and Madras/Chennai). We first review the con sistency of the finding of a "developed versus developing" differential in course and outcome and then examine a variety of course and outcome measure s for the ISoS incidence cohorts. Evidence of differences in illness trajec tory in favor of the developing centers was consistently found. Six potenti al sources of bias are then examined: differences in followup, arbitrary gr ouping of centers, diagnostic ambiguities, selective outcome measures, gend er, and age. None of these potential confounds explains away the differenti al in course and outcome. We conclude with suggestions for further research , with particular attention to the need for close documentation of everyday practices in the local moral,worlds that "culture" refers to.