A proportion of patients may have stroke recurrence while on treatment with aspirin. Some studies have suggested that such recurrence could be partly attributed to biochemical aspirin resistance.

This is an interim analysis from an ongoing study. Patients with ischemic stroke receiving aspirin therapy alone for at least 7 days and within 30 days of the stroke event were enrolled in the study. The effect of aspirin was assessed using Light Transmission Aggregometry and was classified as aspirin resistance, aspirin semi resistance and aspirin sensitive using standard definitions. The Clinical outcome was measured using modified Ranking Score at 3 months and stroke recurrence at one year.

Data of 169 patients is presented. There are 110 males and 59 females, 20 (12%) patients were resistant to aspirin, 47 (28%) were semi- resistant and 102 (60%) patients were sensitive to aspirin. No statistically significant difference was observed on outcome (P value = 0.06) although a trend was observed. The mortality rate was higher in the aspirin resistance group. Statistically significant difference was observed between both the groups (P value= 0.001). Recurrence of stroke was reported in 11 patients; 7 patients were aspirin resistant and 4 patient were sensitive to aspirin.

Interim analysis of the ongoing study suggests that a sizeable proportion of patients could have biochemical aspirin resistance, which could potentially affect stroke related mortality and stroke recurrence.