Follow-up of aspirin-resistant patients with end-stage kidney disease.

BACKGROUND: Aspirin resistance is defined by platelet function testing and presumed clinical unresponsiveness to aspirin. Aspirin-resistant patients are at a greater risk of clinically important adverse cardiovascular events. We aimed to investigate whether end-stage renal disease patients with aspirin resistance are at increased risk for long-term major adverse clinical events. METHODS: We prospectively enrolled 78 end-stage renal disease patients between January 2008 and November 2008. The effect of aspirin on platelet functions was determined using a new generation impedance aggregometer (Multiplate analyser, Dynabyte Medical, Munich). The primary end-point was the composite of death, myocardial infarction, unstable angina, or cerebrovascular accident. Mean follow-up was 20.7 ± 6.1 months. RESULTS: Of the patients studied, 34 (43.58 %) were aspirin resistant and 44 (56.42 %) were not aspirin resistant. Among patients who were aspirin resistant, 13 of 34 (38.2 %) experienced death, MI, or CVA, compared to 7 of 44 (15.9 %) patients who were not aspirin resistant (p = 0.034). Multivariate analyses identified aspirin resistance to be independently associated with major adverse long-term outcomes ([HR] 2.722; 95 % CI, 1.068-6.942; p = 0.04). CONCLUSION: This study demonstrates that end-stage kidney disease patients resistant to aspirin are at a greater risk of long-term major adverse events than patients who are sensitive to aspirin.

Laboratory signs of aspirin response in haemodialysis patients.

INTRODUCTION: Aspirin is effective in the secondary prevention and high-risk primary prevention of cardiovascular events. However, clinical and laboratory evidence demonstrates diminished or no response to aspirin in some patients. This study was designed to assess aspirin response in haemodialysis patients. METHODS: We prospectively enrolled 78 haemodialysis patients (28 female; 58.4 ± 12.6 years old) and 79 patients (29 female; 58.4 ± 10.6 years old) with normal renal function (glomerular filtration rate (GFR) >60 mL/min/1.73 m(2)). All subjects in both the haemodialysis patient group and the control group were taking aspirin (80-300 mg) for at least 30 days and were not taking other antiplatelet agents. Platelet function was assessed by arachidonic acid-induced aggregometry with a Multiplate analyser (Dynabyte Medical, Munich, Germany). Multiplate electrode aggregometry values below 300 AU were applied as a cut-off for response to aspirin. RESULTS: Aspirin non-response was two-fold more prevalent in haemodialysis patients (42.3%) than in patients with normal renal function (21.5%), and this difference was statistically significant (p = 0.005). The two groups were similar in terms of sex, age, tobacco use, the presence of diabetes mellitus, and platelet count. CONCLUSIONS: The frequency of aspirin non-response as defined in this study was higher in haemodialysis patients than in patients with normal renal function. However, larger subsets of patients are needed to confirm the present study.