Table 1.

Baseline demographic characteristics of cases and controls

Characteristic	Cases		Controls
	N	%	N	%
Gender
Male	13	50.0	33	53.2
Female	13	50.0	29	46.8
Racea
White	17	65.4	43	69.3
Black	3	11.5	4	6.5
Native American	0	0.0	1	1.6
Asian/Pacific Islander	1	3.9	6	9.7
Other	4	15.4	8	12.9
Ethnicitya
Hispanic	7	26.9	14	22.6
Non-Hispanic	18	69.2	48	77.4
County of residenceb
Alameda	2	7.7	9	14.5
Contra Costa	1	3.9	6	9.7
Marin	1	3.9	2	3.3
San Francisco	10	38.5	17	27.4
San Mateo	5	19.2	7	11.3
Santa Clara	6	23.1	18	28.0
Solano	1	3.9	1	1.6
Sonoma	0	0	2	3.2
Age group
1–5 years	5	19.2	10	16.1
6–11 years	0	0.0	0	0.0
12–17 years	3	11.5	8	12.9
18–25 years	3	11.5	8	12.9
26–44 years	12	46.2	29	46.8
45–64 years	2	7.7	5	8.1
65+ years	1	3.9	2	3.2
Chronic medical condition
Yes	9	34.6	16	24.2
No	15	61.5	46	74.2
Missing	1	3.9	1	1.6
TOTAL	26c		62

^aOne case refused to provide information on race or ethnicity. ^bDistribution of this variable cannot be meaningfully evaluated because of matching across counties. ^cNo matched controls were recruited for one case; only 25 were analyzed further