The Stockholm non-affective psychoses study (snaps): the importance of including out-patient data in incidence studies

Acta Psychiatr Scand. 2010 May;121(5):389-92. doi: 10.1111/j.1600-0447.2009.01500.x. Epub 2009 Oct 30.


Objective: To estimate the incidence rate of schizophrenia and non-affective psychoses from registers, to highlight the importance of including data from out-patient care, and to assess the proportion of persons treated in out-patient care only.

Method: Data from out-patient and in-patient psychiatric care in Stockholm and information from several national registers constitute 'The Stockholm Non-Affective Psychoses Study' (SNAPS). Incidence rates based on SNAPS data were calculated and compared to in-patient care incidence rates.

Results: The incidence rate was 72/100 000 for non-affective psychoses (age group 18-44) and 28/100 000 for schizophrenia (age group 18-34) in the SNAPS. This was higher compared to in-patient based incidence rates (42 and 13/100 000 respectively). The proportion of individuals with psychosis treated in out-patient care only was 25%.

Conclusion: There are substantial differences in the incidence rates of non-affective psychoses and schizophrenia depending on the availability of data. Not including out-patient care will underestimate the incidence rates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Ambulatory Care / statistics & numerical data*
  • Cross-Sectional Studies
  • Female
  • Health Surveys
  • Hospitalization / statistics & numerical data*
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Psychotic Disorders / diagnosis
  • Psychotic Disorders / epidemiology*
  • Registries
  • Schizophrenia / diagnosis
  • Schizophrenia / epidemiology*
  • Selection Bias
  • Sweden
  • Urban Population / statistics & numerical data*
  • Young Adult