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Cited by 2,168Schizophrenia research and treatmentMental Health Treatment and AccessMental Health and Psychiatry

The DOI matches its Crossref record; 223 of the 240 references it cites were found in a registry or an index, and 16 are not checked yet; none of the 40 sources its claims cite is checked for support yet.

A Systematic Review of the Prevalence of Schizophrenia

Open access
Saha, Sukanta, Chant, David, Welham, Joy, McGrath, John·2005·PLoS Medicine
DOI 10.1371/journal.pmed.0020141PMC PMC1140952
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Abstract

BACKGROUND: Understanding the prevalence of schizophrenia has important implications for both health service planning and risk factor epidemiology. The aims of this review are to systematically identify and collate studies describing the prevalence of schizophrenia, to summarize the findings of these studies, and to explore selected factors that may influence prevalence estimates. METHODS AND FINDINGS: Studies with original data related to the prevalence of schizophrenia (published 1965-2002) were identified via searching electronic databases, reviewing citations, and writing to authors. These studies were divided into "core" studies, "migrant" studies, and studies based on "other special groups." Between- and within-study filters were applied in order to identify discrete prevalence estimates. Cumulative plots of prevalence estimates were made and the distributions described when the underlying estimates were sorted according to prevalence type (point, period, lifetime, and lifetime morbid risk). Based on combined prevalence estimates, the influence of selected key variables was examined (sex, urbanicity, migrant status, country economic index, and study quality). A total of 1,721 prevalence estimates from 188 studies were identified. These estimates were drawn from 46 countries, and were based on an estimated 154,140 potentially overlapping prevalent cases. We identified 132 core studies, 15 migrant studies, and 41 studies based on other special groups. The median values per 1,000 persons (10%-90% quantiles) for the distributions for point, period, lifetime, and lifetime morbid risk were 4.6 (1.9-10.0), 3.3 (1.3-8.2), 4.0 (1.6-12.1), and 7.2 (3.1-27.1), respectively. Based on combined prevalence estimates, we found no significant difference (a) between males and females, or (b) between urban, rural, and mixed sites. The prevalence of schizophrenia in migrants was higher compared to native-born individuals: the migrant-to-native-born ratio median (10%-90% quantile) was 1.8 (0.9-6.4). When sites were grouped by economic status, prevalence estimates from "least developed" countries were significantly lower than those from both "emerging" and "developed" sites (p = 0.04). Studies that scored higher on a quality score had significantly higher prevalence estimates (p = 0.02). CONCLUSIONS: There is a wealth of data about the prevalence of schizophrenia. These gradients, and the variability found in prevalence estimate distributions, can provide direction for future hypothesis-driven research.

Checked 2026-10-06 · 16 references not checked yet

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review collated 1,721 prevalence estimates from 188 studies across 46 countries to describe the distribution of schizophrenia prevalence and examine selected moderators. Median prevalence per 1,000 persons was 4.6 for point, 3.3 for period, 4.0 for lifetime, and 7.2 for lifetime morbid risk, with higher estimates in migrants and higher-quality studies and lower estimates in least developed countries.

Key findings

  • The review identified 1,721 prevalence estimates from 188 studies drawn from 46 countries, based on an estimated 154,140 potentially overlapping prevalent cases; there were 132 core studies, 15 migrant studies, and 41 studies of other special groups.
  • Median prevalence per 1,000 persons was 4.6 for point prevalence (10%–90% quantiles 1.9–10.0), 3.3 for period prevalence (1.3–8.2), 4.0 for lifetime prevalence (1.8–11.6 in the results text), and 7.2 for lifetime morbid risk (3.1–27.1).
  • There was no significant difference between males and females (F 1,72 = 0.68, p = 0.41; male:female median ratio 1.11, 10%–90% quantiles 0.50–1.70) or between urban, rural, and mixed sites (F 2,235 = 1.63, p = 0.20).
  • Migrant status was associated with higher prevalence: median migrant:native-born ratio 1.84 (10%–90% quantiles 0.86–6.41; F 1,2 = 5.57, p = 0.04). Prevalence was significantly lower in “least developed” countries than in “emerging” and “developed” sites (p = 0.04), and higher-quality studies had significantly higher estimates (highest versus lowest quality scores, p = 0.02).

Methods

  • Systematic review following MOOSE guidelines; studies with original prevalence data published January 1965–December 2002 were identified by searching MEDLINE, PsychINFO, EMBASE, and LILACS, checking references, and contacting authors; prison/forensic and genetic family studies were excluded.
  • Estimates were sorted with sequential filters into core, migrant, and other special groups, and into point, period, lifetime, lifetime morbid risk, not otherwise specified, and inpatient-census-derived types; a “most informative” rule selected discrete estimates from overlapping studies.
  • Analyses used cumulative plots and quantiles, with SAS proc univariate and proc mixed to control for within-study variation; combined prevalence estimates were used for planned sensitivity analyses, with Bonferroni correction for post hoc comparisons.

Limitations

  • The authors state that they may have missed studies or made data entry errors; filtering and extraction rules were necessarily ad hoc; combined prevalence estimates were not based on discrete data (8 of 94 studies contributed more than one prevalence type); standard errors could be imputed for only 26% of estimates; and the mixed urban/rural category was likely heterogeneous.
  • The authors also caution against excessive data analyses and note that contributing studies were not designed to test many hypotheses examined in the review.
  • Evident from the text: no formal pooled meta-analysis was performed because of heterogeneity and limited confidence limits, and the migrant analysis was restricted to five papers and 22 prevalence ratios after exclusions.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1371/journal.pmed.0020141

Cites

223 of 239 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 40 cited sources checked · 0 supported · 0 flagged

Show all 61 claims

  • Probably not a substantial claim. 29
  • It may state two separate claims as one. 21
  • The quote only partly states this claim. 1
49 of 49

  • The authors state this as an assumption.

    The course of schizophrenia does not vary according to migrant status.

    “Assuming that the course of the illness does not vary according to migrant status, based on combined prevalence estimates for persons, we predicted that the prevalence of schizophrenia would be higher in migrants than in native-born individuals.”

  • The paper relies on this without support.

    Studies that use comprehensive case ascertainment methods identify more cases than those that rely on fewer recruitment sources.

    “For example, studies that use comprehensive case ascertainment methods (e.g., “door-knock” surveys, inpatient and outpatient records, general practitioner surveys, and/or surveys based on other community sources), should identify more cases than those that rely on fewer recruitment sources.”

  • The paper relies on this without support.

    Prevalence estimates for a disease are not static across time or place.

    “Based on first principles, there is no reason to assume that prevalence estimates for a disease remain static across time or place.”

  • The authors state this as an assumption.

    The oft-quoted statistic that schizophrenia affects about one in a hundred derives from LMR data.

    “It is reasonable to assume that the oft-quoted statistic that “schizophrenia affects about one in a hundred” derives from LMR data (see [234]).”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Abstract and results give different lifetime-prevalence quantiles

    Minor

    The abstract gives lifetime-prevalence 10%-90% quantiles of 1.6-12.1 per 1,000, whereas the results give 1.8-11.6 per 1,000.

  • Discussion understates the reported spread of prevalence estimates

    Minor

    The discussion describes 3.4-fold variation for point prevalence and 4.6-fold for period prevalence. The results instead report approximately 5-fold and 6.5-fold variation for those types, respectively.

  • Study-category totals do not account for overlapping studies

    Minor

    The three category counts add to 188, the reported total number of studies. But the paper says 11 studies appear in two categories, so the counts cannot represent 188 distinct studies.

  • Country counts account for only 33 special-group studies

    Minor

    The counts listed for the 14 countries sum to 33, not the stated 41 special-group studies.

    Reported 41 · recomputed 33

4 of 4

Citations

Cites

Flagged first, then by citations

Show all 240 references

1 of the 240 references couldn’t be matched to a known paper.

Research works printed but not linked: 53

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  4. Chattopadhyay, 1989, Indian J Public Health, 33, 37
  5. Chen, 1998, Chin J Psychiatry, 31, 72
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  7. Cooper, 1983, Nervenarzt, 54, 239
  8. Di Marco, 1982, Acta Psiquiat Psicol Amer Lat, 28, 93
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  10. Fujita, 1991, Nippon Koshu Eisei Zasshi, 38, 233
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  50. Yang, 1989, Chung Hua Shen Ching Ching Shen Ko Tsa Chih, 22, 366
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Metadata

Authors
Saha, S., Chant, D., Welham, J., & McGrath, J.
Affiliations
  • Park Centre for Mental Health (AU)
  • The University of Queensland (AU)
Corresponding author
McGrath, John
ORCID
Venue
PLoS Medicine
Publisher
Public Library of Science (PLoS)
Published
2005-05-31
Volume
2
Issue
5
Pages
e141
ISSN
  • 1549-1277 (ISSN-L)
  • 1549-1676
DOI
10.1371/journal.pmed.0020141
PMC
PMC1140952
OpenAlex
W2113758182
Semantic Scholar
b75013fbff8cc614ea7c3e41ec1aac57ad4efc20
Cited by
2,168
References
240
Citations by year
2026: 82 · 2025: 94 · 2024: 120 · 2023: 139 · 2022: 134 · 2021: 132 · 2020: 137 · 2019: 128 · 2018: 108 · 2017: 114 · 2016: 126 · 2015: 128 · 2014: 122 · 2013: 117 · 2012: 111
FWCI
6.37
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS Medicine (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Figshare (submittedVersion, cc-by)
  • Griffith Research Online (submittedVersion, cc-by)
Funders
Stanley Medical Research Institute
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Schizophrenia research and treatment
  • Health Sciences › Medicine › Psychiatry and Mental health › Mental Health Treatment and Access
  • Social Sciences › Arts and Humanities › Philosophy › Mental Health and Psychiatry
Keywords
schizophrenia, prevalence, lifetime prevalence, point prevalence, period prevalence, migrants, urban-rural differences, sex differences, study quality, risk factors, health planning, risk factor epidemiology
MeSH terms
Female, Humans, Male, Rural Population, Schizophrenia, Sex Factors, Social Class, Urban Population, Prevalence, Epidemiologic Studies, Needs Assessment

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