Health Services Research & Development

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2007 HSR&D National Meeting Abstract

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National Meeting 2007

3078 — Serum Potassium Monitoring and Hyperkalemia in Veterans using Renin-Angiotensin-Aldosterone Inhibitors

Sauer BC (SLC IDEAS) , Nebeker J (SLC IDEAS GRECC), Rupper R (SLC IDEAS GRECC), Samore MH (SLC IDEAS)

Objectives:
Lack of adequate monitoring is a common cause of adverse drug events. ACE-inhibitors (ACE-I) and angiotensin receptor blockers (ARBs) are frequently used in the VA setting, and they are known to cause hyperkalemia in some patients. The objectives of this study were to evaluate (a) monitoring practices in veterans using ACE-I or ARB therapy, and (b) effects of following the National Kidney Foundation (NKF) monitoring recommendations.

Methods:
This study was performed using the SLC VISTA database. The population included patients who were using ACE-I or ARB between 10/01/2003 and 08/31/2005. The NKF recommended monitoring intervals are dependent on baseline or previous renal function and serum K levels. The guideline recommends 12, 4, or 2 week intervals after initiating or changing dose, and 12, 6, or 3 month intervals with stable doses. Moderate-hyperkalemia was defined as K = 6.0 mEq/L and severe -hyperkalemia was defined as K = 6.0 mEq/L. Dialysis patients and inpatient events were excluded from the analysis. Poisson random coefficient analysis was used to test group differences.

Results:
During the study period 16,865 veterans received an outpatient ACE-I or ARB prescription. Overall, 26% of K tests were not within the recommended interval (WRI). 76% of the 5,331 tests following new prescriptions/dose-change were not WRI, and 22% of 52,587 tests when dose was stable were not WRI. The rates of severe and moderate hyperkalemia were 11 and 55 per 1,000 exposed years. In adjusted analysis, not being monitored WRI was associated with a higher rate of both moderate and severe hyperkalemia, IIR: 1.29(95% CI: 1.11-1.49); IIR: 1.77(95% CI: 1.32-2.7), respectively.

Implications:
Veterans who were not monitored according to the NKF recommendations had a higher rate of both moderate and severe hyperkalemia than veterans monitored according to the NKF recommendations. Monitoring practices tended to vary with few veterans receiving recommended monitoring within the VA setting when initiated on ACE-I/ARB or with dose change. Some hyperkalemia may be preventable and patient safety might be improved if patients are monitored more closely.

Impacts:
A better understanding of practices can help to improve appropriate monitoring and reduce adverse drug events. The development and implementation of automated monitoring reminders for the VA Medical Center should be considered.