Table 1.
Characteristics of study participants
| Characteristic | PD cases n = 352 |
Controls n = 352 |
|---|---|---|
| Age at recruitment, yearsa | 60.8 (54.8–65.7) | 60.4 (55.0–65.2) |
| Age at PD diagnosis, years | 68.7 (62.8–74.0) | – |
| Years between recruitment and PD diagnosis | 7.8 (4.6–11.0) | – |
| Sex, n (%)a | ||
| Male | 195 (55%) | 195 (55%) |
| Female | 157 (45%) | 157 (45%) |
| Country, n (%)a | ||
| Italy | 54 (15%) | 54 (15%) |
| Spain | 97 (28%) | 97 (28%) |
| UK | 142 (40%) | 142 (40%) |
| Netherlands | 13 (4%) | 13 (4%) |
| Germany | 46 (13%) | 46 (13%) |
| Smoking status at recruitment, n (%) | ||
| Never smokers | 183 (52%) | 174 (49%) |
| Former smokers | 116 (33%) | 110 (31%) |
| Current smokers | 43 (12%) | 55 (16%) |
| Unknown | 10 (3%) | 13 (4%) |
| BMI categories, n (%) | ||
| BMI < 25 kg/m2 | 119 (34%) | 137 (39%) |
| BMI ≥ 25 | 233 (66%) | 215 (61%) |
Continuous data were expressed as median (interquartile range)
Categorical data were expressed as number (percentage)
BMI body mass index—calculated as the weight in kilograms divided by the square of the height in meters
aMatching variables