title: Assessment of Cotinine Reveals a Dose-Dependent Effect of Smoking Exposure on Long-term Outcomes After Renal Transplantation.
abstract: BACKGROUND
  Smoking is a risk factor for poor late outcomes in renal transplant recipients (RTR). Smoking exposure can be assessed by self-report and cotinine measurements. We investigated whether use of cotinine as a biomarker for smoking exposure can serve as an alternative for self-report and to compare associations of smoking exposure by self-report and cotinine with outcomes in RTR and assess dose dependency.
  
  
  METHODS
  Renal transplant recipients were classified as never, former, light (≤10 cigarettes/day), and heavy smokers (>10 cigarettes/day) according to self-report and analogous categories for urine and plasma cotinine. First, we assessed agreement of self-reported smoking exposure with smoking exposure according urine and plasma cotinine. Second, we compared the associations with graft failure and mortality.
  
  
  RESULTS
  Of 603 RTR (age 51.5 ± 12.1 years, 55% men), 36.0% RTR were never, 42.3% former, 10.6% light, and 11.1% heavy smokers according to self-report. The majority (98.6%) of never smokers had nondetectable cotinine. However, 14 and 13 RTR reporting no active smoking had respective urine or plasma cotinine consistent with active smoking. Cotinine-based measurements were dose-dependently associated with mortality and graft failure.
  
  
  CONCLUSIONS
  Plasma and urine cotinine can serve as an alternative to self-report and were dose-dependently associated with poor late outcomes in RTR.
authors.affiliation: 1 Department of Internal Medicine, University Medical Center Groningen and University of Groningen, Groningen, the Netherlands. 2 Department of Laboratory Medicine, University Medical Center Groningen and University of Groningen, Groningen, the Netherlands. 3 Department of Epidemiology, University Medical Center Groningen and University of Groningen, Groningen, the Netherlands.
authors.forename: Merel E
authors.initials: ME
authors.lastname: Hellemons
authors.forename: Jan-Stephan F
authors.initials: JS
authors.lastname: Sanders
authors.forename: Marc A J
authors.initials: MA
authors.lastname: Seelen
authors.forename: Rijk O B
authors.initials: RO
authors.lastname: Gans
authors.forename: Anneke C
authors.initials: AC
authors.lastname: Muller Kobold
authors.forename: Willem J
authors.initials: WJ
authors.lastname: van Son
authors.forename: Douwe
authors.initials: D
authors.lastname: Postmus
authors.forename: Gerjan J
authors.initials: GJ
authors.lastname: Navis
authors.forename: Stephan J L
authors.initials: SJ
authors.lastname: Bakker
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D003367:Cotinine / Q000097:blood* / Q000652:urine*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000009:adverse effects / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D057566:Self Report; D012907:Smoking / Q000009:adverse effects* / Q000097:blood / Q000401:mortality / Q000652:urine; D016540:Smoking Cessation; D000074606:Smoking Prevention; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D003367:Cotinine