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Cited by 1,072Schizophrenia research and treatmentMental Health Treatment and AccessMental Health and Psychiatry

A systematic review of the incidence of schizophrenia: the distribution of rates and the influence of sex, urbanicity, migrant status and methodology

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McGrath, John, Saha, Sukanta, Welham, Joy, El Saadi, Ossama, MacCauley, Clare, Chant, David·2004·BMC Medicine
DOI 10.1186/1741-7015-2-13PMC PMC421751
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Abstract

BACKGROUND: Understanding variations in the incidence of schizophrenia is a crucial step in unravelling the aetiology of this group of disorders. The aims of this review are to systematically identify studies related to the incidence of schizophrenia, to describe the key features of these studies, and to explore the distribution of rates derived from these studies. METHODS: Studies with original data related to the incidence of schizophrenia (published 1965-2001) were identified via searching electronic databases, reviewing citations and writing to authors. These studies were divided into core studies, migrant studies, cohort studies and studies based on Other Special Groups. Between- and within-study filters were applied in order to identify discrete rates. Cumulative plots of these rates were made and these distributions were compared when the underlying rates were sorted according to sex, urbanicity, migrant status and various methodological features. RESULTS: We identified 100 core studies, 24 migrant studies, 23 cohort studies and 14 studies based on Other Special Groups. These studies, which were drawn from 33 countries, generated a total of 1,458 rates. Based on discrete core data for persons (55 studies and 170 rates), the distribution of rates was asymmetric and had a median value (10%-90% quantile) of 15.2 (7.7-43.0) per 100,000. The distribution of rates was significantly higher in males compared to females; the male/female rate ratio median (10%-90% quantile) was 1.40 (0.9-2.4). Those studies conducted in urban versus mixed urban-rural catchment areas generated significantly higher rate distributions. The distribution of rates in migrants was significantly higher compared to native-born; the migrant/native-born rate ratio median (10%-90% quantile) was 4.6 (1.0-12.8). Apart from the finding that older studies reported higher rates, other study features were not associated with significantly different rate distributions (e.g. overall quality, methods related to case finding, diagnostic confirmation and criteria, the use of age-standardization and age range). CONCLUSIONS: There is a wealth of data available on the incidence of schizophrenia. The width and skew of the rate distribution, and the significant impact of sex, urbanicity and migrant status on these distributions, indicate substantial variations in the incidence of schizophrenia.

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  • Migrants are more likely to develop schizophrenia than native-born individuals (median risk ratio = 4.6).

    “(b) migrants were more likely to develop schizophrenia than native-born individuals (median risk ratio = 4.6);”

    From A Systematic Review of the Prevalence of Schizophrenia (2005) · cites this paper as [1]

  • Males are more likely to develop schizophrenia than females (median male:female risk ratio = 1.4).

    “(a) males were more likely to develop schizophrenia than females (median male:female risk ratio = 1.4);”

    From A Systematic Review of the Prevalence of Schizophrenia (2005) · cites this paper as [1]

  • In a previous systematic review of the incidence of schizophrenia, urban sites had significantly higher incidence rates than mixed urban/rural sites.

    “In the previous systematic review of the incidence of schizophrenia, we found that urban sites had significantly higher incidence rates of schizophrenia than mixed urban/rural sites (there were too few pure rural sites to make the direct urban versus rural comparison) [1].”

    From A Systematic Review of the Prevalence of Schizophrenia (2005) · cites this paper as [1]

  • In a previous study of incidence of schizophrenia, the male:female risk ratio was 1.40.

    “In our previous study of incidence of schizophrenia we found a male:female risk ratio of 1.40 [1].”

    From A Systematic Review of the Prevalence of Schizophrenia (2005) · cites this paper as [1]

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Research works printed but not linked: 1

  1. El-Saadi O Welham J Saha S MaCaulay C Collingwood L Chant D McGrath JJ The incidence and prevalence of schizophrenia: preliminary results from a systematic review Schizophr Res 2001 S49

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Authors
McGrath, J., Saha, S., Welham, J., El Saadi, O., MacCauley, C., & Chant, D.
Affiliations
  • Park Centre for Mental Health (AU)
  • The University of Queensland (AU)
Corresponding author
McGrath, John
ORCID
Venue
BMC Medicine
Publisher
Springer Science and Business Media LLC
Published
2004-04-28
Volume
2
Issue
1
Pages
13-13
ISSN
1741-7015 (ISSN-L)
DOI
10.1186/1741-7015-2-13
PMC
PMC421751
OpenAlex
W2166384797
Cited by
1,072
References
205
Citations by year
2026: 12 · 2025: 26 · 2024: 37 · 2023: 55 · 2022: 36 · 2021: 43 · 2020: 53 · 2019: 68 · 2018: 46 · 2017: 52 · 2016: 58 · 2015: 59 · 2014: 77 · 2013: 75 · 2012: 65
FWCI
4.42
Type
journal article
Language
en
Open access
Licence
www.springer.com/tdm (unspecified)
Locations
  • BMC Medicine (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion, other-oa)
  • PubMed Central (publishedVersion, other-oa)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • Griffith Research Online (submittedVersion, other-oa)
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Schizophrenia research and treatment
  • Social Sciences › Psychology › Social Psychology › Mental Health Treatment and Access
  • Social Sciences › Arts and Humanities › Philosophy › Mental Health and Psychiatry
Keywords
schizophrenia, incidence, sex differences, urbanicity, migrant status, rate distribution, etiology, case finding, diagnostic criteria, age adjustment
MeSH terms
Female, Humans, Male, Rural Health, Schizophrenia, Transients and Migrants, Urban Health, Cohort Studies, Incidence, Sex Distribution

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