STUDY: Watch the NSAID'S

JOURNAL: Am J Med 2003;115:462-466.

AUTHORS: Dr. Dan Caspi

ABSTRACT: Low-dose aspirin therapy may have a significant adverse effect on renal function in elderly patients.

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COMMENTARY: "Although low-dose aspirin is used by many elderly patients, monitoring of renal function is currently not recommended," Dr. Dan Caspi, of Tel Aviv Medical Center, Israel, and colleagues note. "We recently reported transient retention of uric acid and creatinine caused by aspirin doses of 75 to 325 mg/d."

To further investigate, the team examined the renal effects of 100 mg/d of aspirin, including post-treatment effects, in 83 stable geriatric patients treated with low-dose aspirin for 2 weeks and 40 controls. The researchers collected blood samples, and examined 24-hour urinary collections for creatinine and uric acid, at baseline and weekly for 5 weeks.

Urinary excretion of creatinine decreased in 60 (72%) of patients and excretion of uric acid decreased in 54 (65%) after 2 weeks of aspirin therapy. Mean clearance of uric acid also decreased in these patients. During this same time, the team observed increases in serum blood urea nitrogen, creatinine, and uric acid levels (p < 0.05).

"Deterioration from baseline levels was significantly greater (and more prevalent) in the aspirin-treated group than in the 40 control patients," Dr. Caspi and colleagues write.

The authors found that parameters improved after withdrawal of aspirin. However, 3 weeks after cessation of aspirin therapy, 48% of the patients (35/73) had a persistent decline in creatinine clearance of at least 20% lower than baseline, compared with 8% of controls (3/36; p < 0.001).