Angiotensin-converting enzyme inhibitors and other agents that block the renin-angiotensin-aldosterone (RAA) system are used to slow the progression of renal disease in patients with type 2 diabetes and hypertension. However, these drugs can cause hyperkalemia.
While it is widely agreed that serum potassium monitoring is important for patients using these agents, data showing that such monitoring actually helps prevent hyperkalemia is lacking, lead author Dr. Marsha A. Raebel, from Kaiser Permanente Colorado Institute for Health Research, Denver, and colleagues note.
To clarify the benefits of potassium monitoring, the authors analyzed data from diabetic patients without end stage renal disease who began treatment with an RAA inhibitor between 2001 and 2006 at three integrated healthcare systems. The main outcome measure was the rate of serious hyperkalemia-associated events, defined as ER visits, hospitalizations, or deaths within 24 hours of hyperkalemia diagnosis and/or a serum potassium level of 6 mmol/L (6 mEq/L) or higher.
Of the 27,355 patients studied, 19,391 (71%) had potassium tests done during RAA inhibitor treatment.
Serious hyperkalemia-associated events occurred in 184 patients (0.7%), for an incidence rate of 10.2 per 1000 person-years.
Overall, subjects with potassium monitoring were 50% less likely to experience a hyperkalemia event. Among patients with chronic kidney disease, the risk reduction with monitoring was even more pronounced—71%.
On analysis by age, monitoring was found to reduce the risk of hyperkalemia events only in patients 50 years of age and older.
“This study offers tangible evidence to support published guidelines that recommend monitoring serum potassium among patients with these clinical characteristics who are started on renin-angiotensin-aldosterone system inhibitors,” the authors conclude.
J Gen Intern Med 2010.