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A systematic review of the prevalence of schizophrenia.

Saha S, Chant D, Welham J, McGrath J - PLoS Med. (2005)

Bottom Line: Based on combined prevalence estimates, we found no significant difference (a) between males and females, or (b) between urban, rural, and mixed sites.Studies that scored higher on a quality score had significantly higher prevalence estimates (p = 0.02).These gradients, and the variability found in prevalence estimate distributions, can provide direction for future hypothesis-driven research.

View Article: PubMed Central - PubMed

Affiliation: Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, Australia.

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.

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Related in: MedlinePlus

Cumulative Plots of the Male:Female Prevalence Estimate Ratio of Schizophrenia
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pmed-0020141-g009: Cumulative Plots of the Male:Female Prevalence Estimate Ratio of Schizophrenia

Mentions: Table 8 shows the moments and quantiles for the combined prevalence estimates for persons, males, and females, and for a ratio derived from male:female estimates. Figure 8 shows the distribution of these data for males and females—these distributions were not significantly different (F1,72 = 0.68, p = 0.41). For the male:female estimate ratio (based on 57 ratios), the median value was 1.11, and the 10% and 90% quantiles were 0.50 to 1.70 (approximately a 3.4-fold difference) (see Figure 9).


A systematic review of the prevalence of schizophrenia.

Saha S, Chant D, Welham J, McGrath J - PLoS Med. (2005)

Cumulative Plots of the Male:Female Prevalence Estimate Ratio of Schizophrenia
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1140952&req=5

pmed-0020141-g009: Cumulative Plots of the Male:Female Prevalence Estimate Ratio of Schizophrenia
Mentions: Table 8 shows the moments and quantiles for the combined prevalence estimates for persons, males, and females, and for a ratio derived from male:female estimates. Figure 8 shows the distribution of these data for males and females—these distributions were not significantly different (F1,72 = 0.68, p = 0.41). For the male:female estimate ratio (based on 57 ratios), the median value was 1.11, and the 10% and 90% quantiles were 0.50 to 1.70 (approximately a 3.4-fold difference) (see Figure 9).

Bottom Line: Based on combined prevalence estimates, we found no significant difference (a) between males and females, or (b) between urban, rural, and mixed sites.Studies that scored higher on a quality score had significantly higher prevalence estimates (p = 0.02).These gradients, and the variability found in prevalence estimate distributions, can provide direction for future hypothesis-driven research.

View Article: PubMed Central - PubMed

Affiliation: Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, Australia.

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.

Show MeSH
Related in: MedlinePlus