title: Relation of 24-hour urinary caffeine and caffeine metabolite excretions with self-reported consumption of coffee and other caffeinated beverages in the general population.
abstract: BACKGROUND
  Caffeine intake is generally estimated by self-reported consumption, but it remains unclear how well self-report associates with metabolite urinary excretion. We investigated the associations of self-reported consumption of caffeinated drinks with urinary excretion of caffeine and its major metabolites in an adult population.
  
  
  METHODS
  We used data from the population-based Swiss Kidney Project on Genes in Hypertension (SKIPOGH) study. Consumption of caffeinated coffee, decaffeinated coffee and other caffeinated beverages was assessed by self-administered questionnaire. Quantification of caffeine, paraxanthine, theobromine and theophylline was performed by ultra-high performance liquid chromatography tandem mass spectrometry in 24-h urine. Association of reported consumption of caffeinated drinks with urinary caffeine derived metabolites was determined by quantile regression. We then explored the association between urinary metabolite excretion and dichotomized weekly consumption frequency of caffeinated coffee, with Receiver Operator Characteristic (ROC) analysis.
  
  
  RESULTS
  In the present analysis, we included 598 individuals (52% women, mean age =46 ± 17 years). Self-reported caffeinated coffee intake was positively associated with 24-h urinary excretions of paraxanthine, theophylline and caffeine (p< 0.001), whereas reported intakes of decaffeinated coffee and other caffeinated beverages showed no association. In ROC analysis, optimal discrimination between individuals consumingless than one caffeinated coffee/week,vs.at least one coffee,was obtained for 24-h urinary paraxanthine (Area Under Curve (AUC) = 0.868, 95% Confidence Interval (CI) [0.830;0.906]), with slightly lower performance for theophylline and caffeine, whereas theobromine did not allow any discrimination.
  
  
  CONCLUSIONS
  Our results suggest that reported consumption of caffeinated coffee is positively associated with 24-h urinary excretion of caffeine, paraxanthine, and theophylline, and may be used as a marker of caffeine intake for epidemiological studies.
authors.affiliation: Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Route de la corniche 10, Lausanne, 1010 Switzerland.
authors.forename: Dusan
authors.initials: D
authors.lastname: Petrovic
authors.affiliation: Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Route de la corniche 10, Lausanne, 1010 Switzerland.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Estoppey Younes
authors.affiliation: Department of Nephrology and Hypertension, Lausanne University Hospital, Rue du Bugnon 17, Lausanne, 1011 Switzerland.
authors.forename: Menno
authors.initials: M
authors.lastname: Pruijm
authors.affiliation: Department of Nephrology and Hypertension, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland.
authors.forename: Belén
authors.initials: B
authors.lastname: Ponte
authors.affiliation: University Clinic for Nephrology, Hypertension and Clinical Pharmacology, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, Bern, 3010 Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ackermann
authors.affiliation: Department of Cardiology, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland.
authors.forename: Georg
authors.initials: G
authors.lastname: Ehret
authors.affiliation: Unit of Pharmacogenetics and Clinical Psychopharmacology, Centre for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly, 1008 Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ansermot
authors.affiliation: Department of Nephrology and Hypertension, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Mohaupt
authors.affiliation: Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Route de la corniche 10, Lausanne, 1010 Switzerland.
authors.forename: Fred
authors.initials: F
authors.lastname: Paccaud
authors.affiliation: University Clinic for Nephrology, Hypertension and Clinical Pharmacology, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, Bern, 3010 Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Vogt
authors.affiliation: Department of Nephrology and Hypertension, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland.
authors.forename: Antoinette
authors.initials: A
authors.lastname: Pechère-Bertschi
authors.affiliation: Department of Nephrology and Hypertension, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Martin
authors.affiliation: Department of Nephrology and Hypertension, Lausanne University Hospital, Rue du Bugnon 17, Lausanne, 1011 Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Burnier
authors.affiliation: Unit of Pharmacogenetics and Clinical Psychopharmacology, Centre for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly, 1008 Switzerland ; School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.
authors.forename: Chin B
authors.initials: CB
authors.lastname: Eap
authors.affiliation: Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Route de la corniche 10, Lausanne, 1010 Switzerland.
authors.forename: Murielle
authors.initials: M
authors.lastname: Bochud
authors.affiliation: Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Route de la corniche 10, Lausanne, 1010 Switzerland ; Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine and Primary Care and Emergency Medicine, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland ; Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, USA ; Lausanne University Outpatient Clinic, Rue du Bugnon 44, Lausanne, 1011 Switzerland ; Unit of Population Epidemiology, University Hospital of Geneva (HUG), Rue Gabrielle Perret-Gentil 4, Geneva, 1205 Switzerland.
authors.forename: Idris
authors.initials: I
authors.lastname: Guessous
keywords: Caffeine; Paraxanthine; Population-based; Questionnaire; Theophylline; Urinary excretion