Mortality, ESRD Risk Rise for Elderly Post-MI Patients
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In elderly patients hospitilized for myocardial infarction, small increases in serum creatinine increase risks of later end-stage renal disease and death.
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Small increases in serum creatinine levels during hospitalization, already known to increase short-term risk of end-stage renal disease (ESRD) and death, also raise those same risks in the long term, UAB physicians reported recently in the Archives of Internal Medicine (2008;168[6]:609-616).
Nephrologist Britt B. Newsome, MD, led the retrospective study of elderly Medicare patients (mean age, 77.1 years) admitted to hospitals following acute myocardial infarction (AMI). Newsome and colleagues suggest targeting elderly patients with creatinine increases while hospitalized post-AMI for closer monitoring and more aggressive treatment.
“In our sample, giving beta-blockers and aspirin decreased mortality rates in the long-term regardless of creatinine change during hospitalization, but patients with larger creatinine changes were undertreated,” he says. “Incidences of ESRD and death were greatest among patients with larger changes in creatinine level, and every level of severity of creatinine increase was associated with greater independent risks of ESRD and mortality.”
Acute kidney injury (AKI) is an acute increase in baseline serum creatinine. A common complication of hospitalization, AKI occurs in 5% to 7% of patients. Among Medicare patients AKI incidence has risen 11% each year since 1992. If hospitalized patients with AKI require dialysis, the associated mortality rate exceeds 50%.
Despite higher mortality during hospitalization, most patients with reduced kidney function survive to discharge. “Our results demonstrate that small degrees of creatinine change among elderly patients not requiring dialysis during hospitalization are associated with a higher ESRD risk after discharge,” he says.
Newsome’s group plumbed the same cohort to find that blacks had an increased 10-year risk of ESRD regardless of baseline function that was not accounted for by differences in pre-ESRD mortality (Am J Kid Dis. 2008;52[2]:251-261).
In recognition of adverse events associated with small changes in creatinine levels, the Acute Kidney Injury Network has suggested defining the least severe AKI stage as an abrupt increase in serum creatinine ≥0.3 mg/dL or a 1.5-fold or more increase from baseline. “The long-term risks we observed suggest that even the least severe stage of kidney injury may indicate a worse prognosis,” Newsome says. Some of these increases in creatinine are below what current assays can detect, and more sensitive measures of AKI would be helpful, as would biomarker identification. Future research should attempt to unravel the reasons for the association between small serum creatinine changes and adverse outcomes, he says.
“Our findings are limited to a specific population—elderly patients who have had a heart attack. This is a group of patients in whom subsequent cardiac catheterizations with nephrotoxic contrast dye constitute a risk for AKI,” he says.
“Further research is needed to determine risk-lowering strategies for all hospitalized patients, and older patients should be a focus of these efforts. The long-term clinical impact of AKI among older individuals is of particular importance given its increasing incidence and high prevalence in this age group,” he says.
For more information contact Dr. Britt Newsome at 1-800-UAB-MIST or at mist@uabmc.edu.