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

Khalakdina et al. BMC Public Health 2003 3:11   doi:10.1186/1471-2458-3-11