Table 1

General characteristics of cases and controls

PD cases (n=444)Controls (n=876)
Men, N (%)281 (63.3)557 (63.6)
Age at interview, median (range)68 (34–91)68 (34–90)
Age at diagnosis, median (range)67 (34–90)
Cigarette smoking*
 Never smoked, N (%)207 (46.6)243 (27.7)
 >0–7.8 pack-years, N (%)86 (19.4)161 (18.4)
 >7.8–17.5 pack-years, N (%)67 (15.1)155 (17.7)
 >17.5–29.4 pack-years, N (%)45 (10.1)160 (18.3)
 >29.4–103 pack-years, N (%)39 (8.8)157 (17.9)
Coffee consumption†
 0–97 consumption-years, N (%)128 (28.8)220 (25.1)
 >97–156 consumption-years, N (%)146 (32.9)221 (25.3)
 >156–214 consumption-years, N (%)90 (20.3)216 (24.7)
 >214–720 consumption-years, N (%)80 (18.0)218 (24.9)
Occupational skill and status‡
 High-skilled white-collar worker, N (%)198 (44)335 (38)
 Low-skilled white-collar worker, N (%)87 (20)187 (21)
 High-skilled blue-collar worker, N (%)101 (23)202 (23)
 Low-skilled blue-collar worker, N (%)58 (13)152 (17)
  • *Pack-years of cigarette smoking was calculated by dividing average number of cigarettes per day by 20 multiplied with the number of years of smoking. Pack-years were divided based on the quartiles of the exposure distribution among the controls.

  • †Consumption-years were calculated by multiplying the average amount of coffee consumptions per day (cups per day) with the estimated number of years of coffee consumption. Consumption-years were divided based on the quartiles of the exposure distribution among the controls. Coffee consumption information was missing for one control.

  • ‡The categories of occupational skill and status were made according to major International Standard Classification of Occupations 1988 (ISCO88) groups (first digit of the job codes). 1–3: high-skilled white-collar jobs, 4–5: low-skilled white-collar jobs, 6–7: high-skilled blue-collar jobs, and 8–9: low-skilled blue-collar jobs. The participants were categorised according to the group in which they had worked most years during their career.

  • PD, Parkinson disease.