High frequency of aspirin resistance in patients with nephrotic syndrome

Aspirin has a beneficial role in prevention of cardiovascular and thromboembolic events. Patients may experience thromboembolic events despite aspirin treatment, a phenomenon called aspirin resistance. We evaluated the frequency of aspirin resistance and its correlation with clinical and biochemical parameters among patients with nephrotic syndrome (NS).

A total of 83 patients (50 males, 33 females, age range 18-79 years) with NS using aspirin 100 mg/day were included in the study. Demographic information and aetiology of NS based on the histology of a renal biopsy were recorded for each patient. Blood samples were drawn to investigate the association of aspirin resistance with inflammation and thrombotic risk factors. Aspirin resistance was defined as a normal collagen/epinephrine closure time<159 s using a platelet function analyzer (PFA-100).

Aspirin resistance was determined in 51 patients (61.4%). The number of patients exposed to azathioprine therapy was significantly higher in the aspirin-sensitive group (P=0.043), whereas patients exposed to cyclosporine therapy were significantly higher in the aspirin-resistant group (P=0.017). More patients in the aspirin-resistant group were on angiotensin-converting enzyme inhibitor therapy compared with the aspirin-sensitive group (P=0.024). The aspirin-resistant group showed significantly higher serum low-density lipoprotein cholesterol (LDL-C) (151±47 versus 104±21 mg/dL; P<0.001), triglyceride levels (192±116 versus 134±82 mg/dL; P=0.015) and glomerular filtration rates (91.8±43.0 versus 74.0±35.6 mL/min/1.73 m2; P=0.044) compared with the aspirin-sensitive group. In multivariate analysis, LDL-C was the only parameter associated independently with aspirin resistance [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02-1.06; P=0.004].

A significant number of patients with NS are resistant to aspirin therapy. Serum LDL-C level is closely associated with aspirin resistance in NS.