Cause of Death in Patients with Reduced Kidney Function

Abstract

Information on common causes of death in people with CKD is limited. We hypothesized that, as eGFR declines, cardiovascular mortality and mortality from infection account for increasing proportions of deaths. We calculated eGFR using the CKD Epidemiology Collaboration equation for residents of Alberta, Canada who died between 2002 and 2009. We used multinomial logistic regression to estimate unadjusted and age- and sex-adjusted differences in the proportions of deaths from each cause according to the severity of CKD. Cause of death was classified as cardiovascular, infection, cancer, other, or not reported using International Classification of Diseases codes. Among 81,064 deaths, the most common cause was cancer (31.9%) followed by cardiovascular disease (30.2%). The most common cause of death for those with eGFR≥60 ml/min per 1.73 m(2) and no proteinuria was cancer (38.1%); the most common cause of death for those with eGFR<60 ml/min per 1.73 m(2) was cardiovascular disease. The unadjusted proportion of patients who died from cardiovascular disease increased as eGFR decreased (20.7%, 36.8%, 41.2%, and 43.7% of patients with eGFR≥60 [with proteinuria], 45-59.9, 30-44.9, and 15-29.9 ml/min per 1.73 m(2), respectively). The proportions of deaths from heart failure and valvular disease specifically increased with declining eGFR along with the proportions of deaths from infectious and other causes, whereas the proportion of deaths from cancer decreased. In conclusion, we found an inverse association between eGFR and specific causes of death, including specific types of cardiovascular disease, infection, and other causes, in this cohort.

Keywords: CKD; GFR; cardiovascular disease; epidemiology and outcomes; mortality.

Figure 1.

Participant flow and characteristics for all residents of Alberta over the study period. The sensitivity analysis shown on the lower right, excluded all eGFR measurements in the month prior to death. SCr, serum creatinine.

Figure 2.

Unadjusted relative percentages for death by cause and eGFR. Top panel shows the relative percentages for death by eGFR category for each of the four main categories: CVD, neoplasm, infection, and other. The most common cause of death for those with eGFR>60 ml/min per 1.73 m² and no proteinuria was cancer. The most common cause of death for those with eGFR<60ml/min per 1.73m² was cardiovascular disease. Middle panel shows the relative percentages for death by eGFR category for the subclassification of other causes from top panel. Among participants without proteinuria and eGFR>60 ml/min per 1.73 m², neurologic diseases (including dementia) were the most common cause of death. At lower eGFR, the proportions of death caused by unclassified and diabetic complications increased. Bottom panel shows the relative percentages for death by eGFR category for the subclassification of CVD deaths. For participants with eGFR>60 ml/min, death caused by ischemic heart disease (IHD) was the most common cause of cardiovascular death. The proportion of deaths caused by heart failure and valvular disease increased at lower eGFR. The height of each colored bar represents the percentage of participants for each cause of death within each category of eGFR. The width of each colored bar represents the percentage of participants for each eGFR category within each cause of death. The area of each colored bar represents the percentage of participants within each eGFR category and each cause of death. Prot, proteinuria.