Table 1

Demographic characteristics of 92 cases and 92 matched controls

CasesControls
Gender, n (%)
    Male37 (40)37 (40)
    Female55 (60)55 (60)
Age in years, mean (range)14.8 (13–16)15.1 (13–16)
School year, n (%)
    S11 (1)1 (1)
    S229 (32)29 (32)
    S328 (30)27 (29)*
    S434 (37)35 (38)*
Social deprivation score, mean (SD)4.6 (1.6)4.2 (1.5)
  • There were no substantial or statistically significant differences between cases and controls on the variables above. *One control for a case in S3 had entered S4 by the time of the interview.