This study aimed to identify predictors of hyperkalemia and renal impairment in congestive heart failure (CHF) patients taking spironolactone and furosemide.
Ninety (90) consecutive patients with CHF, 46M/44F, mean age 73.8 (range 56.4 -91.2 yrs) were studied. We started 26 patients while 20 patients were already taking spironolactone and furosemide when the study started. We measured blood electrolytes every two months. The study started from April 2003 and lasted two years. Mean observation duration was 489 days for 124 patient years with a mean 19 visits and a mean 25 days between visits.
Baseline characteristics: Mean(SD) left ventricular ejection fraction (LVEF): 39.5%(15.1); mean(SD) creatinine concentration(mg/dl): 0.91(0.25); mean serum potassium(mEq/dl): 4.3(0.4); mean(SD) dosage (mg/day): spironolactone: 14.9(7.3), furosemide: 30.3(14.1); patients needing angiotensin converting enzymes (ACE) inhibitors or angiotensin receptor blockers (ARB): n=50(50%), β blockers: 48(53%); mean peak creatinine concentration: 1.07(SD 0.34) mg/dl; mean peak potassium: 5.0(SD 0.5)mEq/dl. A total of 45(50%) had creatinine > 1.04 mEq/dl, 16(18%) > 1.30, 9(10%) > 1.50. Relative to baseline, 24(27%) patients had creatine increase by 20%, 15(17%) by 30%, 8(9%) by 50%, 2(2%) by 100%. A total of 39(43%) patients had potassium > 5.0 mEq/dl, 9(10%) >5.5, 2(2%) > 6.0. Patients taking spironolactone and furosemide before study started did not differ significantly from patients we started in terms of hyperkalemia (potassium >5.5)(11.5% vs. 15.2%, p=0.54) and azotemia (creatinine > 1.30)(15.3% vs. 14.1%, p=0.82). We logistically regressed (30% increase in serum creatinine concentrations) with age, sex, use of ACE inihibitors, ARBs, β blockers, and dosage of spironolactone and furosemide. Age (odds ratio 1.24(95% confidence index interval 1.01-2.54)for each ten years)) was an independent risk factor for azotemia.For hyperkalemia (potassium > 5.5), we added to the model baseline creatinine concentrations and found that age (1.03(0.84-2.86)) was a predictive factor.
Age was a predictor of hyperkalemia and azotemia for patients taking spironolactone and furosemide with moderately decreased LVEF.
Caution should be taken while dose adjustment and continuous monitoring may be needed in elderly patients.
Nobuyuki Anzai, None.