An evaluation of hyperkalemia and serum creatinine elevation associated with different dosage levels of outpatient trimethoprim-sulfamethoxazole with and without concomitant medications.

BACKGROUND: Adverse events associated with high-dose trimethoprim-sulfamethoxazole (TMP-SMX) for outpatient infections, particularly those likely caused by community-acquired methicillin-resistant Staphylococcus aureus, have not been adequately characterized.
OBJECTIVE: Describe hyperkalemia and acute renal injury associated with high-dose TMP-SMX.
METHODS: An electronic medical record database retrospective study was conducted of outpatients receiving high-dose or low-dose TMP-SMX, comparing the incidences of hyperkalemia and acute renal injury.
RESULTS: Of 6162 patients, more developed hyperkalemia (3.06% vs 1.05%, P < .0001) or acute renal injury (1.99% vs 0.700%, P = .0001) in the high-dose TMP-SMX group. Variables independently associated with hyperkalemia included age >58 years (odds ratio [OR] = 3.44; 95% CI = 1.86-7.0; P < .0001), concomitant receipt of an NSAID (OR = 1.71; 95% CI = 1.02-2.79; P = .044) or an ACE inhibitor (OR = 3.27; 95% CI = 2.06-5.14; P < .0001), high-dose TMP-SMX prescribed (OR = 2.92; 95% CI = 1.85-4.60; P < .0001), and baseline elevated serum creatinine (OR = 45.1; 95% CI = 21.7-93.2; P < .0001). Variables independently associated with acute renal injury included concomitant receipt of an ACE inhibitor (OR = 2.36; 95% CI = 1.01-5.24; P = .048) or a potassium supplement (OR = 4.10; 95% CI = 1.45-10.1; P = .010), high-dose TMP-SMX prescribed (OR = 3.70; 95% CI = 1.70-8.12; P = .0012), and baseline elevated serum creatinine (OR = 2110; 95% CI = 724-7980; P < .0001).
CONCLUSIONS: Serum creatinine and potassium concentrations should be monitored in outpatients receiving high-dose TMP-SMX.