. Author manuscript; available in PMC: 2019 Jan 15.

Published in final edited form as: JAMA Dermatol. 2016 Nov 1;152(11):1218–1224. doi: 10.1001/jamadermatol.2016.2536

Table 3.

Spatial Clusters of Basal Cell Carcinoma (BCC), January 1, 2011, to December 31, 2012, Adjusted for Age, Sex, and Neighborhood Socioeconomic Status, Kaiser Permanente Northern California

Cluster No., Location	Radius, km	Member-years	No. of BCC Cases		Observed Cases per 100 000 Person-years^a	Relative Risk vs Outside Cluster (95% CI)	P Value
Cluster No., Location	Radius, km	Member-years	Expected	Observed	Observed Cases per 100 000 Person-years^a	Relative Risk vs Outside Cluster (95% CI)	P Value
1, Marin County	17	105 751	1421	1814	1666	1.29 (1.11–1.50)	<.001
2, Northeast Sacramento County	14	134 576	1468	1770	1264	1.22 (1.08–1.37)	<.001
3, East Contra Costa and west San Joaquin Counties	14	41 876	352	491	1125	1.40 (1.15–1.71)	<.001
4, West central Contra Costa County	10	89 535	1310	1531	1645	1.18 (1.07–1.30)	<.001
5, Eastern Sonoma and northern Napa Counties	36	197 179	2077	2311	1139	1.12 (1.03–1.21)	.006

The observed incidence of basal cell carcinoma outside these 5 clusters was 964 cases per 100 000 person-years.