Table 1 Background information for cases and controls
DataAll cases (n = 959)Cases with Parkinson’s disease (n = 767)Controls (n = 1989)All cases vs controls(p value)
Age, mean (SD)69.9 (9.5)69.8 (9.2)69.8 (10.0)
Sex, No (%)
    Male537 (56)426 (56)1057 (53)
    Female422 (44)341 (44)932 (47)
Age left school (years), mean (SD)14.5 (2.6)14.5 (2.6)14.4 (2.7)0.20†
Currently working, No (%)90 (9)66 (9)334 (17)0.001‡
Friend/relative helped with responses, No (%)287 (30)227 (30)214 (11)0.001‡
Age at diagnosis (years), mean (SD)62.4 (10.3)61.6 (9.9)n/a
Interview quality assessment, No (%)*
    Poor/confused, but plausible176 (19)137 (18)253 (13)
    Good766 (81)616 (82)1685 (87)
  • *Interview quality was categorised by the interviewer as implausible when the subject was unable to respond to basic questioning or provided data that were illogical or implausible. Where recall was occasionally poor or confused, but in the main sounded plausible, this was coded as poor/confused, but plausible. Where the subject provided good, precise responses and the work history was well described the interview quality was categorised as good.

  • t Test; ‡χ2 test; §χ2 test combining “implausible” and “poor/confused, but plausible” categories.