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. Author manuscript; available in PMC: 2016 Apr 1.
Published in final edited form as: J Autism Dev Disord. 2015 Apr;45(4):988–1000. doi: 10.1007/s10803-014-2253-0

Table 1.

Description of ASD study population and relative risk (RR) hotspots

Sample Birth Cohort Study Year Agea Surveillance Populationb (n) Cases (n) Controls (n) Hotspots (n) Maximum RR Cases in hotspots (n) Total area of hotspot(km2)c
1994–8 1994 2002 8 26,213 132 2640 1 2.3 42 69.0
1998–8 1998 2006 8 29,494 182 3560 0 2.7 0d 0d
2000–6 2000 2006 6 32,801 223 4460 2 1.8 48 154.52
2000–8 2000 2008 8 33,757 295 5900 2 2.6 18 41.22
2002–4 2002 2006 4 33,955 166 3320 2 2.5 33 261.92
2002–6 2002 2008 6 34,368 289 5780 3 3.0 66 359.29
2004–4 2004 2008 4 35,803 186 3720 1 2.0 43 142.78
a

Age at surveillance

b

ASD surveillance conducted in Davis, Salt Lake and Utah counties

c

Total area of surveillance region=9,274.6 km2

d

No evidence of heightened areas of relative risk in this birth cohort*ascertainment age sample