Objective: To explore clinical and laboratory factors associated aspirin response, and the association between gastrointestinal bleeding and aspirin response in aged patients.
Methods: A total of 136 patients aged 60 and over [mean age (74.9 ± 7.0) years] with ischemic heart disease and at high risk for ischemic heart disease were included. Arachidonic acid induced platelet aggregation (AA-Ag) was measured before and at 7(th) day after taking aspirin (100 mg/d). Patients were followed for 6 months and incidence of gastrointestinal bleeding was obtained.
Results: Post-treatment AA-Ag was significantly reduced compared to baseline (13.29% ± 5.52% vs. 73.20% ± 7.32%, P < 0.05). A heterogeneous distributed post-treatment AA-Ag was observed (range 0.42% to 30.50%). Post-treatment AA-Ag was positively correlated with baseline AA-Ag (r = 0.493, P < 0.01). The level of post-treatment AA-Ag was significantly higher in the fourth quartile group at baseline than in the others quartile groups at baseline. Patients aged 80 years and over had significantly lower post-treatment AA-Ag (10.25% ± 4.68%) compared with patients of 60 - 69 years (13.96% ± 5.20%) and of 70 - 79 years (13.73% ± 5.48%, all P < 0.01). The incidence of patients in the lowest quartile of post-treatment AA-Ag was significantly higher in patients ≥ 80 years (38.24%) than in patients of 60 - 69 years (11.1%) and of 70 - 79 years (24.0%). Multiple variable analysis revealed post-treatment AA-Ag was significantly influenced by baseline AA-Ag, ≥ 80 years old, diabetes mellitus and acute coronary syndrome. We observed 4 (2.9%) mild gastrointestinal bleeding during follow up. Post-treatment AA-Ag was in the lowest quartile in 3 patients with mild gastrointestinal bleeding.
Conclusions: Increased baseline platelet reactivity as well as diabetes mellitus and acute coronary syndrome are associated with low aspirin response in the aged patients. Aspirin response is significantly higher in very old patients.