. 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 2.

Spatial Clusters of Basal Cell Carcinoma (BCC), January 1, 2011, to December 31, 2012, Adjusted for Age and Sex, 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	107190	1408	1841	1668	1.33 (1.12–1.57)	<.001
2, West central Contra Costa County	12	105170	1414	1741	1594	1.25 (1.10–1.43)	<.001
3, East Contra Costa and west San Joaquin Counties	14	41 876	347	491	1125	1.42 (1.15–1.75)	<.001
4, Eastern Sacramento County	24	110577	1110	1350	1174	1.23 (1.09–1.39)	<.001
5, Southern San Mateo and eastern Santa Clara Counties	24	65 197	875	1058	1569	1.22 (1.08–1.37)	<.001
6, Central Placer County near Lincoln	3	11397	235	321	2711	1.37 (1.11–1.70)	.004
7, Eastern Sonoma and northern Napa Counties	28	58483	740	882	1457	1.20 (1.04–1.38)	.01

The observed incidence of BCC outside these 7 clusters was 944 cases per 100 000 person-years.