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Table 2 Adjusted medians for 24-h excreted urinary metabolites [mg] according to the consumption frequencies of caffeinated coffee, other caffeinated beverages and decaffeinated coffee (quantile regression)

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

  Never 1–4×/Month 1–4×/Week 5×/Week > = 1×/day P for trenda ρ c P d
Adjusted medians for 24-h urinary caffeine [mg] (winsorised 99th percentile)
 Caffeinated coffee
  Unadjusted model 0.791 1.270 1.890 2.469 3.612 <0.001 0.473 <0.001
 Fully adjusted modelb 1.382 1.655 2.262 2.959 3.724 <0.001   
 Other caffeinated drinks
  Unadjusted model 3.144 3.116 2.521 1.787 2.954 0.578 −0.069 0.090
  Fully adjusted modelb 3.419 3.285 3.034 1.899 3.268 0.702   
 Decaffeinated coffee
  Unadjusted model 2.694 2.842 2.787 6.576 3.128 0.374 0.039 0.346
  Fully adjusted modelb 3.273 2.929 3.022 4.586 3.032 0.612   
Adjusted medians for 24-h urinary paraxanthine [mg] (win. 99th perc.)
 Caffeinated coffee
  Unadjusted model 2.331 4.269 6.833 6.923 12.512 <0.001 0.528 <0.001
  Fully adjusted modelb 3.847 4.287 7.174 8.755 12.456 <0.001   
 Other caffeinated drinks
  Unadjusted model 12.361 9.993 8.706 8.361 10.706 0.469 −0.061 0.133
  Fully adjusted modelb 12.781 10.506 9.368 8.533 11.150 0.185   
 Decaffeinated coffee
  Unadjusted model 9.875 9.571 9.500 17.852 11.407 0.324 0.057 0.164
  Fully adjusted modelb 10.498 10.271 10.188 11.503 11.829 0.494   
Adjusted medians for 24-h urinary theophylline [mg] (win. 99th perc.)
 Caffeinated coffee
  Unadjusted model 0.266 0.353 0.660 0.689 1.163 <0.001 0.519 <0.001
  Fully adjusted modelb 0.347 0.396 0.603 0.835 1.145 <0.001   
 Other caffeinated drinks
  Unadjusted model 1.036 1.007 0.734 0.724 0.935 0.093 −0.075 0.069
  Fully adjusted modelb 1.100 0.982 0.842 0.684 0.965 0.519   
 Decaffeinated coffee
  Unadjusted model 0.870 1.034 0.683 1.406 1.081 0.155 0.040 0.329
  Fully adjusted modelb 0.933 0.901 0.749 1.563 0.923 0.972   
Adjusted medians for 24-h urinary theobromine [mg] (win. 99th perc.)
 Caffeinated coffee
  Unadjusted model 11.352 12.911 13.743 11.747 10.977 0.398 −0.019 0.637
  Fully adjusted modelb 10.361 11.231 13.992 11.286 11.949 0.726   
 Other caffeinated drinks
  Unadjusted model 11.900 10.287 11.456 10.904 11.623 0.870 0.013 0.746
  Fully adjusted modelb 13.256 11.203 10.854 9.342 13.351 0.472   
 Decaffeinated coffee
  Unadjusted model 10.889 12.125 11.773 11.097 12.369 0.445 0.045 0.271
  Fully adjusted modelb 11.588 12.635 11.056 9.516 14.604 0.178   
  1. a P-value for linear trend (Reported consumption frequency: lowest vs. highest)
  2. bModel was adjusted for age, sex, BMI, urinary creatinine, glomerular filtration rate, urinary volume, urinary flow, study center, smoking and alcohol status
  3. cSpearman correlation coefficient (ρ) for the association between self-reported consumption frequency and 24-h urinary excretion
  4. dSpearman correlation coefficient associated p-value