Mean follow-up serum potassium was 5.0 mEq/L for spironolactone , 4.7 mEq/L for losartan ( P = 0.05 versus spironolactone ) , and 4.5 mEq/L for placebo ( P < 0.001 versus spironolactone ; P = 0.03 versus losartan ) .