Schizophrenia is not disappearing in south-west Scotland

Background Recent work has reported a decline in the incidence or schizophr enia, but it is unclear if these findings reflect a true decrease in its in cidence or are an artefact arising from methodological difficulties. Aims To take account of these methodological difficulties and report servic e-based incidence rates for schizophrenia in Dumfries and Galloway in south -west Scotland for 1979-98. Method Using both clinical diagnoses and diagnoses generated from the Opera tional Checklist for Psychotic Disorders (OPCRIT) computer algorithm for IC D-10 and DSM-IV schizophrenia, we measured change in the incidence rates ov er time. We used indirect standardisation techniques and Poisson models to measure the rate ratio linear trend. Results There was a monotonic and statistically significant decline in clin ically diagnosed schizophrenia. The summary rate ratio linear trend was 0.7 7. However, using OPCRIT-generated ICD-10 and DSM-IV diagnoses, there was n o significant difference over time. Conclusions OPCRIT-generated consistent diagnoses revealed no significant f all in the incidence of schizophrenia. Changes in diagnostic practice have caused the declining rates of clinically diagnosed schizophrenia in Dumfrie s and Galloway.