Table 1

 Characteristics of cases and controls

Cases (n = 280)Controls (n = 285)p
No.%No.%
*Matching variables.
NS: p > 0.05.
Sex
    Male16659.316658.3NS
Age* (y)
    <23311.85117.8
    2–38530.45218.3
    4–68329.67827.4
    7–104114.66322.1
    ⩾113813.64114.4<0.01
Centre*
    Lille3913.9269.1
    Lyon3612.93512.3
    Nancy238.2227.7
    Paris18265.020270.9NS
Origin*
    European24487.123682.8
    North African155.4238.1
    Other217.5269.1NS
Socioeconomic status
    High14752.516055.1
    Intermediate5519.64917.2
    Low7827.97526.3NS
    Missing value00.010.4
Education of mother
    >High school9032.110837.9
    ⩽High school19067.917561.4NS
    Missing value00.020.7
Education of father
    >High school8731.19934.7
    ⩽High school18164.617059.7NS
    Missing value124.3165.6
Family situation
    Couple24788.224284.9
    Widow/separate269.33512.3
    Single72.551.8NS
    Missing values00.031.1
Type of dwelling
    Urban22178.923482.1
    Rural5820.74917.2NS
    Missing value10.420.7