In risk analysis both cotinine levels and CPD were positively associated with lung cancer risk (OR=1.34 95%CI 1.29-1.39 Ptrend =2*10−53 per decile of CPD , and OR=1.36 95%CI 1.3-1.4; Ptrend =3*10−73 per 200 nmol/L of cotinine. Figure 1, Supplementary Tables 1 and 2). The risk increased monotonically with increasing cotinine levels, and reached an OR of 19.6 (95%CI 12.5-30.8) for subjects having cotinine levels above 1800nmol/L. The estimated RDR taking into account within-person variation was 0.86 and correction for regression dilution resulted in notably higher ORs than from uncorrected measurements (Figure1). In contrast, the risk increase associated with CPD deciles reached a plateau at 20-21 CPD and the maximum observed OR was 16.4 (95%CI 10.3-26.1) for CPD levels of between 21 and 26.9 (Figure 1, Supplementary Table 1). Mutual adjustments of cotinine and CPD attenuated the maximum risk association for CPD from OR=16.4 to OR=6.5 which is a considerably greater attenuation than seen for the maximum odds ratio for cotinine (OR=19.6 to OR=12.4, Figure 1).
