Table 2.

Schizophrenia Prevalence in Disadvantaged vs Advantaged Groups at Different Latitudes

First Author	Study Site	Study Date	Schizophrenia Prevalencea (No. Surveyed)				Relative Risk (with 95% CL)	Absolute Latitudeb
			Disadvantaged Group		Relatively Advantaged Group
Roy	Canada	c.1970	Native American	5.7 (4273)	Whites	1.6 (28 096)	3.58 (2.2, 5.8)***	52.8
Zhang	USA; ECA sites (except L.A.)	1980	African American	16.3 (4481)	Whites	9.4 (11 298)	1.75 (1.3, 2.4)**	38.8
Zhang	USA; L.A.	1980	African Americanc	6.4 (157)	Whites	6.1 (1646)	1.05 (0.1, 8.2)	33.7
Jablensky	India	1978–1979	Rurald	4.8 (61 642)	Urban	3.1 (205 786)	1.55 (1.35,1.78)***	30.4
Rin	Taiwan	c. 1962	Aboriginese	1.1 (5302)	Han Chinese	2.1 (19 931)	0.47 (0.2, 1.1)	25.0

Note: The relative risk (in disadvantaged vs advantaged groups) rather than the absolute prevalence should be compared across different sites because in this table the studies at different sites did not all use the same methods.

^aSchizophrenia prevalence is the estimated number of cases per 1000 adults in the population surveyed.

^bAbsolute latitude (in degrees north or south of the equator).

^cData on Los Angeles were analyzed separately from the other US ECA sites because published data were available for Los Angeles as opposed to the other specific ECA sites, and Los Angeles is of particular interest for our analyses because its latitude is lower than that of the other ECA sites.

^dWhile subjects from both rural and urban Chandigarh were disadvantaged relative to Western countries, the investigators described their subjects from their rural sample as coming from poorer neighborhoods with a higher illiteracy rate than in the urban sample.

^eThe investigators described the Ayatal aborigines as the least technologically advanced ethnic Taiwanese group; their main livelihood was from hunting and fishing.

**P < 0.005; ***P < 0.0005; all P values are 2 tailed.