Aim: The ineffectiveness of antiplatelet treatment with aspirin is a widely discussed problem today. It is usually described with individual diseases. In old age, the patient is polymorbid and uses numerous treatments. This work enquires into how polymorbidity and polymedication can have an influence on the anti-aggregation effect of aspirin.
Methods: A group of 508 patients, who used 100 mg aspirin daily, was examined. Clinical and laboratory tests were carried out on all, and pharmacotherapy analysis was conducted. Selected, concurrently used medicines were divided into 12 groups. Levels of 11-dehydrothromboxane B2 (11-dTxB2) in the first morning urine sample were examined in all cases.
Results: Of the 508 patients, 233 patients (46%) showed insufficient suppression of urinary thromboxanes. In the resistant group, a statistically significant negative correlation was found with a higher concentration of C-reactive protein and smoking, from co-morbidity with atrial fibrillation and ischemic cerebral stroke in the case history. The risk of ineffective anti-aggregation therapy is increased 1.8 times by smoking and 1.6 times by ischemic cerebral stroke. Every increase in C-reactive protein by one unit increases the ineffectiveness of anti-aggregation therapy by 1.3 times. From the field of pharmacotherapy, a significant positive statistical effect on treatment with statins and nitrates occurred, and a negative effect with digoxin. The possible effectiveness and ineffectiveness of anti-aggregation treatment were not, in this study, influenced to a statistically significant degree by the presence of ischemic coronary disease, ischemic diseases of the lower limbs, arterial hypertension, diabetes and heart failure.
Conclusion: Anti-aggregation treatment with aspirin in doses of 100 mg per day is, for a major part of polymorbid patients, insufficient. The risk of ineffectiveness of the treatment is increased by smoking, increased levels of C-reactive protein, and from comorbidities of atrial fibrillation and ischemic cerebral stroke. From the point of view of concurrently used medicines, the risk is increased by treatment with digoxin and on the other hand, reduced by treatment with statins and nitrates.