Low Dose Aspirin Prophylaxis for Cardiovascular Disease in the Elderly Population: Is it safe for the Kidney?

Objectives: To evaluate the effects of Low dose Aspirin (LDA) 75mg/day on renal function and uric acid (UA) handling in elderly patients with normal renal function. Study Design: Case control study. Place and Duration: This study was conducted at the Cardiology and Medical clinics of Pakistan Institute of Medical Sciences (PIMS), Islamabad over a period of four months. Materials and Methods: Sixty elderly patients with the Mean age 58.9±6.82 years and range 50-75 years were divided equally in case and control groups. The case group received LDA 75mg/day for two weeks and then discontinued. The control group did not receive aspirin. Patients were excluded if they had serum creatinine (Scr) more than 1.5mg/dl and glomerular filtration rate (GFR) less than 90ml/min determined by MDRD equation or had a contraindication to aspirin use. Blood samples were tested at base line, at 2 weeks of aspirin therapy, and at 4 weeks (i.e. after 2 weeks of cessation of aspirin) for serum levels of urea, creatinine, uric acid and GFR, estimated by both Cockroft-Gault (CG) and MDRD equation. Results: The base line renal function in aspirin and control group did not differ. After 2 weeks of aspirin therapy only serum UA increased significantly from base line in aspirin group (33.7%) vs. contro l group (6.14%), mean change 1.607±1.797 vs. 0.28±1.342, respectively (P=0.008), while serum urea , creatinine and GFR remained unchanged in the two groups. After 2 weeks of cessation of aspirin, serum UA returned to base line value in aspirin group and serum urea, creatinine and GFR did not change from base line in two groups. Conclusion: Short term low dose aspirin 75mg/day does not affect renal function in elderly patients who have normal renal functions at baseline and does not require renal function monitoring.