Survival data show ‘immense burden’ of ESKD on mortality
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Key takeaways:
- Estimating risk of mortality for patients with kidney failure is difficult because of other illnesses.
- Patients with kidney failure have among the lowest relative survival compared to other chronic diseases.
Compared with illnesses like cancer, heart failure and dementia, patients with end-stage kidney disease alone have among the lowest rates of survival after 5 years, Stanford University researchers reported in a published study.
“Estimates of mortality from kidney failure are misleading because the mortality from kidney failure is inseparable from the mortality attributed to comorbid conditions,” Margaret R. Stedman, PhD, MPH, from the division of nephrology in the school of medicine at Stanford University, and colleagues wrote. “We sought to develop an alternative method to reduce the bias in estimating mortality due to kidney failure using life table methods.”
In the study, Stedman and colleagues used life tables to determine estimates of mortality among patients with kidney failure alone compared with similar-aged people in the general population.
“Relative survival using comorbidity-adjusted life tables gives us a less biased estimate of the mortality burden from kidney failure that may be easier to communicate to policymakers and patients,” the authors wrote. “Furthermore, it can be directly compared across age, sex, race, year and comorbidity groups, which makes it ideal for national and international research where demographics vary.”
Stedman and colleagues reviewed data from the U.S. Renal Data System based on a 5% sample of the Medicare population to create two study groups: a cohort of patients aged 66 years and older who first had kidney failure in 2009 and a second group from the general population cohort without kidney failure. Primary outcome was death.
Results showed patients with kidney failure “have roughly one-third the likelihood of survival compared with similar (by age, sex, race and comorbidity) persons without kidney failure in the United States,” the authors wrote. “Based on our comorbidity-adjusted life tables, patients 66 [to] 70 years old with kidney failure have an average survival (36% observed) comparable to persons 86 [to] 90 years old (33% expected survival) without kidney failure.
In an interview with Healio, Stedman said the focus of the study was to show how mortality can be assessed based on kidney failure alone. “We performed the analysis because, from a surveillance/policy perspective, it is difficult to disentangle how much of death is due to comorbidity vs. chronic kidney disease. In our paper we show that deaths in patients with ESKD (from the surveillance vantage point), are mainly attributed to CKD.”
Stedman said there are unanswered questions about the best clinical approach for treating elderly patients with kidney disease. “Relative survival is a hypothetical estimate that is useful in considering how diseases progress in the absence of comorbid conditions,” Stedman said. “A different, more nuanced, analysis would be needed to weigh the benefit of treating patients in the presence of other causes of death to determine if treating elderly patients with dialysis extends their lifespan or improves quality of life. Our results show elderly patients have a higher mortality, despite adjusting for age and comorbidity-related mortality. Therefore, we recommend more early detection and prevention of disease.”
Results also showed Black patients in the study had lower excess mortality due to kidney failure alone (119 deaths/1,000 person years) vs. white patients (193 deaths/1,000 person years), “a finding contrary to that observed with other chronic diseases,” the authors wrote.
“Estimates of survival relative to a matched general population partition the mortality due to kidney failure from other causes of death,” the authors wrote. “Results highlight the immense burden of kidney failure on mortality and the importance of disease prevention efforts among older adults.”
In an accompanying editorial, Eric D. Weinhandl, PhD, MS, said use of U.S. Renal System data may not capture all patients with kidney failure, but the study by Stedman and colleagues and previous studies “consistently support” the value of early detection of chronic kidney disease.
“This view supports targeted CKD screening and wider access to medical therapies that prevent CKD progression, such as sodium/glucose cotransporter-2 inhibitors and mineralocorticoid receptor antagonists,” Weinhandl wrote.
Future research should focus on assessing “whether relative survival after kidney failure has changed during past decades, whether owing to decreasing mortality on in-center hemodialysis, increasing utilization of home dialysis or increasing incidence of deceased-donor kidney transplantation,” Weinhandl wrote.
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