Dose-response of aspirin on platelet function in very elderly patients / 北京大学学报(医学版)

ABSTRACT

Objective:To assess the consequences of switching aspirin dosage from 100 mg/d to 40 mg/d on cardiovascular benefit,bleeding risk and platelet aggregation in very elderly patients. Methods:Arachidonic acid induced platelet aggregation(AA-Ag)was measured in 537 patients aged 80 or older treated with aspirin (100 mg/d).In the study,100 patients with low on-treatment platelet ag-gregation and at high risk of bleeding and low risk of cardiovascular events,were switched to aspirin (40 mg/d)and their platelet aggregation was measured again 7 days later.Their bleeding and upper gastroin-testinal symptoms were also recorded in following 3 months.Results:The study observed a heterogeneous distributed aspirin 100 mg/d AA-Ag (range0.42% to 28.78%)in the 537 very elderly patients.Aspi-rin 100 mg/d AA-Ag before the switch in aspirin 40 mg/d group was 5.00% ±2.32% and the rate of the patients with low on-treatment platelet aggregation was 71.00%.The rates of melena or occult blood positive,other minimal bleeding,upper gastrointestinal symptoms and a history of gastrointestinal bleeding in 40 mg/d group were higher than those in 100 mg/d group.On a regimen of aspirin 40 mg/d,AA-Ag increased to 11.21% ±4.95%(range2.12% to 28.84%)with 95.00%of the patients with AA-Ag<20%and the rate of the patients with low on-treatment platelet aggregation was 15.00%.Multiple vari-able analysis revealed that aspirin 40 mg/d AA-Ag was significantly influenced by aspirin 100 mg/d AA-Ag,BMI and platelet counts.The rate of gastrointestinal bleeding decreased from 12.00% to 5.00%, and upper gastrointestinal symptoms decreased from 59.00% to 21.00% after the switch in 40 mg/d group.Conclusion:Switching aspirin dosage from 100 mg/d to 40 mg/d reduces the bleeding events and improves upper gastrointestinal symptoms,thus inhibiting platelet aggregation effectively in very elderly patients.