Table 1

Distribution (n, %) of study and sociodemographic variables for controls and for cases stratified on availability of ERPR results status

VariableControlsCasesCasesχ2 (obtained versus missing)
ERPR results obtainedERPR results missing
n(%)n(%)n%
Study
 ECSS (1995–1996)721(20)649(20)65(14)0.01
 WHS (1996–1998)2970(80)2617(80)415(86)
Household income
 Low406(11)359(11)51(11)0.99
 Middle1189(34)1064(34)159(35)
 High1200(34)1134(36)165(36)
 No answer749(21)567(18)81(18)
Marital status
 Married2756(75)2408(74)357(75)0.85
 Single180(5)166(5)27(6)
 Divorced/separated309(8)303(9)44(9)
 Widowed423(12)372(11)49(10)
Education
 ≤Grade 8470(13)366(11)67(14)0.20
 Grades 9–131615(45)1500(47)209(44)
 College/university1542(43)1340(42)201(42)