Cotinine Levels Predict Poor Outcome After Renal Transplant

Daniel M. Keller, PhD

November 05, 2012

SAN DIEGO, California — Plasma and urinary cotinine measures predict poor outcome in renal transplant recipients in a dose-dependent fashion, researchers reported here at Kidney Week 2012: American Society of Nephrology 45th Annual Meeting.

Because cotinine levels correlated with self-reported smoking, they could serve as an objective alternative, noted Merel Hellemons, MD, and colleagues from the Department of Internal Medicine at the University Medical Center in Groningen, the Netherlands.

Smoking has been identified as a risk factor for poor outcome after renal transplantation. As part of their study, the researchers tested whether cotinine, an alkaloid in tobacco and a metabolite of nicotine, could serve as a biomarker for nicotine exposure. They also examined the relation between self-reported smoking or cotinine levels and outcomes after transplantation.

The researchers classified the 603 renal transplant recipients (mean age, 51.5 years; 55% male) according to their self-reported smoking status — never smokers, former smokers, light smokers (10 or fewer cigarettes/day), or heavy smokers (more than 10 cigarettes/day) — and according to urine and plasma cotinine levels. They then tested these parameters for an association with graft failure and mortality.

At study enrollment, 217 (36.0%) kidney recipients reported being never smokers, 255 (42.3%) reported being former smokers, 64 (10.6%) reported being light smokers, and 67 (11.1%) reported being heavy smokers.

Self-reported daily cigarette use was highly correlated with cotinine levels. In most of the nonsmokers, cotinine was undetectable, but urine cotinine level was consistent with active smoking in 14 patients, as was plasma cotinine level in 13 patients. About 12% of the urine or plasma cotinine levels and the smoking self-reports were discordant.

The risk for graft failure correlated with the degree of smoking. The greatest risk was among heavy smokers, followed by light smokers, and the least risk was among never and former smokers. However, heavy smokers and former smokers had than never smokers.

The researchers noted that although there was a dose-dependent relation between cotinine levels and both graft failure and mortality, independent of potential confounders, there was no dose-dependent relation between poor outcome and self-reported smoking status. TTherefore, they suggest that plasma and urinary cotinine might be good alternatives to self-reported smoking status. These values could predict the risk for poor outcomes after renal transplantation.

Kidney Week 2012: American Society of Nephrology 45th Annual Meeting. Abstract TH-PO1052. Presented November 1, 2012.