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Abstract: FR-PO305

Mortality Associated with Hyperkalemia in Medicare Patients

Session Information

Category: Fluid and Electrolytes

  • 902 Fluid and Electrolytes: Clinical

Authors

  • Woolley, J. Michael, AstraZeneca, Wilmington, Delaware, United States
  • Betts, Keith, Analysis Group, Inc. , Los Angeles, California, United States
  • Mu, Fan, Analysis Group, Los Angeles, California, United States
  • Wang, Yao, Analysis Group, Los Angeles, California, United States
  • Dua, Akanksha, Analysis Group, Los Angeles, California, United States
  • Wu, Eric, Analysis Group, Los Angeles, California, United States
Background

The objective of this study was to compare all-cause mortality between patients with and without hyperkalemia in the U.S. Medicare population.

Methods


Adult patients with and without hyperkalemia (cases vs. controls), were selected from a 5% random sample from the Medicare population (1/1/2010-12/31/2014). Hyperkalemia was defined as having at least one diagnosis of hyperkalemia (ICD-9-CM 276.7). The index date was a randomly selected claim date with a hyperkalemia diagnosis for cases and a randomly selected claim date for controls. Continuous enrollment for at least 6 months before the index date (baseline period) was required and patients were followed from the index date to death or the end of data availability (study period). Controls were exactly matched one-to-one to cases on age group, chronic kidney disease (CKD) stage, dialysis, and heart failure (HF). Mortality outcomes were analyzed at 36 months. Time to death was estimated with Kaplan-Meier analysis and compared using the log-rank test. Hazard ratios (HRs) were estimated using univariate and multivariate Cox proportional hazards (PH) models.

Results


A total of 157,441 cases were matched to 157,441 controls. Compared with controls in the overall population, cases had higher 3-year mortality rates (47.5% vs. 33.7%) and lower median time to death (40.3 months vs. median not reached). Among the 79,327 matched pairs of patients with CKD and/or HF, the 3-year mortality was higher (59.6% vs. 48.7%) and the median time to death was lower (22.7 vs. 38.4 months) (p for log-rank test<0.001) in cases compared with controls. In univariate Cox PH models, the risk of mortality was significantly higher for cases compared with controls overall (HR: 1.67, 95% CI: 1.65, 1.69) and among patients with CKD and/or HF (HR: 1.44; 95% CI: 1.42, 1.46) (all p<0.001). After adjusting for age, gender, region, diabetes, hypertension, and Charlson Comorbidity Index, the risk remained higher for cases compared with controls in the overall population (HR: 1.49, 95% CI: 1.48, 1.51) and among patients with CKD and/or HF (HR: 1.37, 95% CI: 1.35, 1.39) (all p<0.001).

Conclusion


In this study of Medicare patients, hyperkalemia was associated with increased mortality.

Funding

  • Commercial Support