Prevalence of psychoses in Stockholm County—A population-based study using comprehensive healthcare registers

Abstract

Background: Major variations in the prevalence of schizophrenia and other psychoses have been reported in different geographical areas, partly explained by the methodology used as well as characteristics of the area. Aims: The purpose of this study was to estimate the 1-year prevalence of schizophrenia (ICD-10 F20) and non-affective psychoses (ICD-10 F20–F29) in Stockholm County using population-based health records from inpatient and outpatient care. Methods: Psychiatric outpatient and inpatient healthcare data during the period 1997 to 2006 in Stockholm County was collected from mental health facilities in a defined geographical area covering almost one million adult inhabitants. Data included 13,561 individuals with ICD-10 diagnoses of non-affective psychoses, their contacts with healthcare and demographic variables constituting the Stockholm Non-Affective Psychoses-registry. Results: The 1-year prevalence was 6.7/1000 for non-affective psychoses and 3.7/1000 for schizophrenia. The estimates were markedly stable during the study period, years 2000–2005. However, a substantial variation in the 1-year prevalence between areas in Stockholm County was noted (range 3.5/1000–13.2/1000). The 1-year prevalence was correlated to the proportion of immigrants as well as the proportion of individuals receiving social welfare benefits, in the area. An increase in the proportion of individuals only visiting outpatient care was seen. Conclusion: The 1-year prevalence of schizophrenia was 3.7/1000 and approximately twice as high for non-affective psychoses. The estimates were stable over time but varied substantially between local areas, corresponding to social and demographic factors.

• Non-affective psychoses
• Prevalence
• Register
• Schizophrenia

Acknowledgement

The authors thank Mattias Agestam, Lars Bejhed, Guy Karlsson and Anna Åberg Wistedt for help in gaining access to data from registers and Margareta Falk Hogstedt for scrutinizing medical records.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

The study was supported by the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet.