Cotinine as a marker for risk prediction in the Ludwigshafen Risk and Cardiovascular Health Study

• Cotinine is a biochemical marker of tobacco smoke burden.
• We examined cotinine as predictor of mortality in smokers and nonsmokers.
• Cotinine is a strong predictor of all-cause and cardiovascular mortality.
• Cotinine as marker is as good or superior than other indicators of smoking.

BackgroundCotinine is one of the major metabolites of nicotine. The aim our study was to investigate cotinine as a marker for individual risk prediction in the Ludwigshafen Risk and Cardiovascular Health study.Methods840 samples had detectable cotinine measured using a radioimmunoassay (RIA nicotine metabolite, DPC Biermann GmbH). The distribution of risk factors across quartiles of cotinine or pack-years was analyzed by ANOVA and the association of cotinine and pack-years with mortality by Cox regression.ResultsCotinine and pack-years both showed significant association with mortality in adjusted models with HRs (95% CI) of 1.30 (1.17–1.44) and 1.26 (1.13–1.42) comparing the third to the first tertile for cotinine and pack-years, respectively. Either cotinine or pack-years or self-reported smoking increased the area-under-the-curve significantly as compared to a basic model including other risk factors.DiscussionCotinine is a strong predictor of mortality in non-smokers as well as in smokers. As objectively measurable parameter cotinine would be preferable for risk prediction.