Secular trends in cardiovascular mortality rates of patients receiving dialysis compared with the general population

Abstract

Background: Cardiovascular mortality rates in the general population have decreased over time. We hypothesized that cardiovascular mortality rates in dialysis patients, which are higher than in the general population, have not decreased as much as those in the general population.

Study design: Comparison of registry data with population data.

Setting & participants: Data for prevalent Australian patients for whom dialysis was the first renal replacement therapy were obtained from the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry for 1992-2005. Data for a comparable Australian general population were obtained from the Australian Bureau of Statistics.

Outcome: Cardiovascular mortality rates per 100 person-years were calculated from ANZDATA Registry data, and age-specific relative risks were calculated relative to cardiovascular mortality rates in the general population.

Results: Included in this cohort were 34,741 dialysis patients with 93,112 person-years of follow-up and 7,267 cardiovascular deaths. Cardiovascular mortality rates decreased over time in the general population and in dialysis patients older than 55 years. In patients aged 55-64 years, cardiovascular mortality rates were 9.0 (95% CI, 7.8-10.3) per 100 person-years in 1992-1994 and 6.4 (95% CI, 5.5-7.3) in 2004-2005; corresponding relative risks were 32.4 (95% CI, 28.2-37.2) and 52.0 (95% CI, 45.2-59.9), respectively. The corresponding cardiovascular mortality rates for dialysis patients aged 65-74 years were 11.6 (95% CI, 10.4-13.0) and 8.3 (95% CI, 7.4-9.3); relative risks were 12.9 (95% CI, 11.6-14.5) and 20.8 (95% CI, 18.7-23.2). Using negative binomial regression, the relative risk associated with dialysis compared with the general population increased over time (P for interaction = 0.001).

Limitations: Causes of death used to define cardiovascular mortality were not coded using identical systems in the ANZDATA Registry and the Australian population.

Conclusions: Despite decreasing cardiovascular mortality rates in some dialysis patients, the excess cardiovascular risk compared with the general population is increasing.