In the 5-year follow-up period, a total of 822 out of the initially 1932 included individuals died. The age-adjusted mortality risk according to the three PON1 polymorphisms is shown in Tables 2 and 3 for women and men, respectively. The data indicate that the PON1 192Q/R polymorphism may be an independent mortality risk factor and most pronounced in women, the estimated hazard rate for RR homozygotic women being 1.38 (95% CI: 1.01–1.87, P¼ 0.04) using the QQ genotype as the reference group, while the corresponding number for men was 1.14 (P¼0.55).

To confirm the results for this polymorphism in a sample, we genotyped a further 541 individuals who available from the 1905 cohort. A total of 404 out of 541 individuals died during follow-up. The hazard rate for RR homozygotic women in the sample was 1.38 (P¼ 0.09), while effect was less in men (hazard rate¼1.31, P¼0.66). Looking at combined group of samples 1 and 2, the hazard rate 1.38 (P¼0.008) for women and 1.20 for men (P¼0.43).

aMean follow-up time for survivors was 5.1 years (range 4.7–7.1 years). bAge-adjusted mortality risk using the genotypes (cid:1)107CC, 55MM and 192QQ as reference group, respectively.

bAge-adjusted mortality risk using the genotypes (cid:1)107CC, 55MM and 192QQ as reference group, respectively.

Adjusting for other available covariates, such as smoking status, BMI, hypertension, heart failure and self-rated health did not change the magnitude of the hazard rate estimates; hence, these are not included in the final analysis.

period). We furthermore observed a significantly decreased mortality risk in 55M/L heterozygotic women only (hazard rate 0.69, P¼0.007), and a non-significant trend towards a decreased risk in 55LL homozygotes (hazard rate 0.83,

The increased mortality risk seen for 192RR homozygotic women was evident in all age groups above 70 years (only six women below 70 years of age died during the follow-up

Table 4 PON192Q/R genotypes according to self-re- ported ischemic heart diseasea

Table 3 Mortality risk according to PON1 genotypes in a 5-year follow-upa in men

192QQ 192QR 192RR Women +Disease 90 (50.6%) 67 (37.6%) 21 (11.8%) (cid:1)Disease 723 (54.5%) 492 (37.1%) 111 (8.4%) Men +Disease 60 (56.6%) 40 (37.7%) 6 (5.7%) (cid:1)Disease 453 (52.1%) 363 (41.7%) 54 (6.2%)

Hazard rateb 95% CI P-value PON1 genotypes Sample 1 (N¼863) (cid:1)107CC 1 (cid:1)107CT 1.03 0.81–1.32 0.80 (cid:1)107TT 1.15 0.87–1.51 0.33 55MM 1 55ML 0.99 0.72–1.35 0.93 55LL 0.98 0.71–1.35 0.88 192QQ 1 192QR 1.01 0.82–1.24 0.94 192RR 1.14 0.74–1.78 0.55 Sample 2 (N¼111) 192QQ 1 192QR 0.98 0.64–1.52 0.94 192RR 1.31 0.40–4.23 0.66 55MM 1 55ML 1.14 0.53–2.45 0.74 55LL 0.86 0.41–1.93 0.76 Sample 1+2 (N¼974) 192QQ 1 192QR 0.99 0.83–1.21 0.98 192RR 1.20 0.78–1.78 0.43

aAngina and/or myocardial infarction.

with age. The increased frequency of 55M/192R carriers with age reported by Bonafe´ et al11 could thus not be replicated here.

However, the longitudinal study, which could be ex- pected to be more statistically powerful, revealed an increased mortality among women homozygous for 192RR, while the effect was smaller in men. Thus, in a 5- year follow-up period, we found that 192RR homozygotic women had a mortality risk of 1.38 (P¼0.04) compared to individuals with the QQ genotype. Although not formally statistically significant, replication in a new sample (sample 2) confirmed this result (hazard rate: 1.38, P¼0.09). Combining samples 1 and 2 did not change the risk estimate, but increased the statistical significance to P¼0.008, thereby adding further support to the moderate but significant effect of this genotype on mortality risk in women.

aMean follow-up time for survivors was 5 years (range 4.6–7.2 years). bAge-adjusted mortality risk using the genotypes (cid:1)107CC, 55MM and 192QQ as reference group, respectively.

P¼0.17) compared to 55MM homozygotes. However, these results were not replicated in sample 2.

Table 4 provides the genotype distribution for PON 192Q/R according to ischemic heart disease (angina and/or myocardial infarction). There is a nonsignificant increased proportion of RR homozygotes in women suffering from ischemic heart disease (11.8%) compared to both men (6.2%) and women (8.4%) with no experience of ischemic heart disease.

We did not obtain information about the cause of death in this study, as the Danish Registry of Causes of Death is updated to year 2000 only, making it insufficient for the main part of the 5-year follow-up time used in this study. Hence, we cannot directly ascribe the reported poorer survival chance of 192RR homozygotic women to an increased susceptibility to CHD and death. Instead, we used self-reported data on ischemic heart disease (angina and/or acute myocardial infarction) in order to examine whether the increased mortality seen in 192RR women may possibly be caused by an increased susceptibility to development of CHD. We found a slightly higher propor- tion of RR homozygotes in the disease group compared to the nondisease group (11.8 vs 8.4%) in women. However, this did not reach statistical significance. This observation is in line with the results of the recent meta-analysis conducted by Wheeler et al9 showing that PON 192Q/R was only weakly associated with CHD susceptibility.

Discussion

Although reports have been contradictory, several studies have suggested an association between PON1 polymorph- isms and susceptibility to cardiovascular disease. As cardiovascular disease is one of the leading causes of death in middle-aged and elderly people, an impact of such polymorphisms on mortality could be expected.