Table 1.
Baseline characteristics of participants included in the study (N = 598), SKIPOGH study (Switzerland, 2009–2013)
| Men (n = 288) | Women (n = 310) | P-valuea, b | |
|---|---|---|---|
| Age, mean (SD) | 46.16 (17.41) | 46.17 (17.28) | 0.972 |
| BMI (kg/m2), mean (SD) | 25.84 (4.1) | 24.08 (4.56) | <0.001 |
| Glomerular filtration rate, mean (SD) | 97.46 (19.1) | 95.68 (17.43) | 0.116 |
| Urinary parameters | |||
| Urinary volume (ml/24-h), mean (SD) | 1751.38 (801.87) | 1687.39 (682.89) | 0.635 |
| Urinary flow (ml/min), mean (SD) | 1.23 (0.57) | 1.19 (0.5) | 0.663 |
| Urinary creatinine (mg/kg/24-h), mean (SD) | 22.33 (5.46) | 18.35 (4.38) | <0.001 |
| Urinary caffeine (mg/24-h), median (IQR) | 2.76 (3.61) | 2.85 (4.03) | 0.891 |
| Urinary paraxanthine (mg/24-h), median (IQR) | 11.33 (11.49) | 9.43 (9.44) | <0.001 |
| Urinary theobromine (mg/24-h), median (IQR) | 11.63 (12.78) | 10.9 (11.95) | 0.212 |
| Urinary theophylline (mg/24-h), median (IQR) | 0.95 (1.09) | 0.89 (0.96) | 0.347 |
| Study center, n (%) | 0.805 | ||
| Lausanne | 83 (29%) | 97 (31%) | |
| Geneva | 101 (35%) | 105 (34%) | |
| Bern | 104 (36%) | 108 (35%) | |
| Smoking, n (%) | 0.024 | ||
| No | 212 (74%) | 252 (81%) | |
| Yes | 76 (26%) | 58 (19%) | |
| Alcohol consumption, n (%) | <0.001 | ||
| No | 62 (22%) | 135 (44%) | |
| Yes | 226 (78%) | 175 (56%) | |
| Caffeinated coffee consumption | 0.219 | ||
| Never | 23 (8%) | 41 (13%) | |
| 1–4 times/month | 15 (5%) | 21 (7%) | |
| 1–4 times/week | 18 (6%) | 22 (7%) | |
| ≥ 5 times/week | 11 (4%) | 11 (4%) | |
| ≥ 1 time/day | 221 (77%) | 215 (69%) | |
| Other caffeinated drink consumption, n (%) | 0.755 | ||
| Never | 53 (18%) | 56 (18%) | |
| 1–4 times/month | 76 (26%) | 88 (28%) | |
| 1–4 times/week | 65 (23%) | 59 (19%) | |
| ≥ 5 times/week | 16 (6%) | 14 (5%) | |
| ≥ 1 time/day | 78 (27%) | 93 (30%) | |
| Decaffeinated coffee consumption, n (%) | 0.004 | ||
| Never | 233 (81%) | 210 (68%) | |
| 1–4 times/month | 31 (11%) | 62 (20%) | |
| 1–4 times/week | 8 (3%) | 15 (5%) | |
| ≥ 5 times/week | 2 (1%) | 6 (2%) | |
| ≥ 1 time/day | 14 (5%) | 17 (5%) | |
Data are mean (SD) or median (IQR) for continuous variables and N (%) for categorical variables
aMann–Whitney U test was performed between men and women for continuous variables
bChi2 contingency test was performed between men and women for categorical variables