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Table 1 Baseline characteristics of participants included in the study (N = 598), SKIPOGH study (Switzerland, 2009–2013)

From: Relation of 24-hour urinary caffeine and caffeine metabolite excretions with self-reported consumption of coffee and other caffeinated beverages in the general population

  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%)  
  1. Data are mean (SD) or median (IQR) for continuous variables and N (%) for categorical variables
  2. aMann–Whitney U test was performed between men and women for continuous variables
  3. bChi2 contingency test was performed between men and women for categorical variables