Differences in cardiovascular mortality rates among hemodialysis patients in the United States and Japan: the importance of background cardiovascular mortality.

Mortality rates among hemodialysis patients differ greatly among the United States, Europe, and Japan and it has been hypothesized that this is mainly due to differences in practice patterns. Results from the international DOPPS study, however, indicate that differences in practice patterns among the United States, Japan, and Europe are small and not alone explanatory for the differences in mortality rates. Ethnic variability in predisposition to atherosclerotic cardiovascular disease in the general population may lead to significant differences in background cardiovascular mortality in the United States, Japan, and Europe. It is our hypothesis that cardiovascular mortality in dialysis patients is to a great extent dependent on cardiovascular background mortality of the general population. We are currently studying the relationship between all-cause and cardiovascular death rates in countries worldwide using the WHO database. Preliminary data from 35 countries show that all-cause and cardiovascular death rates differ significantly among regions, with Eastern European countries reporting four- to sevenfold higher death rates than Asian countries. A strong linear relationship between cardiovascular and all-cause death rates is observed among these countries. The next step of our study will be to compare country-specific cardiovascular death rates of dialysis populations with those of the respective general populations. Ethnic differences in cardiovascular morbidity and mortality may be explained by genetic variability based upon polymorphism of genes involved in the pathogenesis of atherosclerosis and myocardial infarction.