Comparison of the incidence of schizophrenia in rural Dumfries and Galloway and urban Camberwell

BACKGROUND: Being born or living in urban areas is associated with high rates of schizophrenia. However, few studies have compared the incidence in urban/rural areas using the same methodology. AIMS: To compare service-based incidence rates for schizophrenia in rural Dumfries and Galloway in south-west Scotland with urban Camberwell in south-east London. METHOD: Using Research Diagnostic Criteria diagnoses from the OPCRIT computer algorithm, we compared the incidence of schizophrenia over 12 years (1979-1984 and 1992-1997) using indirect standardisation techniques and Poisson regression modelling. RESULTS: The incidence was 61% higher in urban Camberwell than in rural Dumfries and Galloway (standardised incidence ratio (SIR)=1.61; 95% CI=1.42-1.81). There was no difference in incidence when we compared the White population in Camberwell with Dumfries and Galloway (SIR=1.12; 95% CI=0.86-1.43). CONCLUSIONS: The incidence of schizophrenia in urban Camberwell was higher than that in rural Dumfries and Galloway; the high incidence of non-Whites in Camberwell largely explains the urban/rural difference.