Cause of Death in Patients with Reduced Kidney Function

TLDR

Common causes of death among CKD patients are poorly characterized. The study aimed to determine whether lower eGFR is linked to higher proportions of cardiovascular and infection deaths. Using CKD‑EPI eGFR estimates and multinomial logistic regression on Alberta death records (2002‑2009), the authors classified causes of death by ICD codes and compared proportions across CKD stages. In 81,064 deaths, cancer was the overall leading cause, but as eGFR declined cardiovascular deaths rose while cancer deaths fell, showing an inverse relationship between kidney function and cause‑specific mortality.

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 m2 and no proteinuria was cancer (38.1%); the most common cause of death for those with eGFR<60 ml/min per 1.73 m2 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 m2, 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.