Relationship between non-specific prescription pill adherence and ischemic stroke outcomes

Adherence to non-specific prescription therapy may be associated with clinical outcomes beyond a given treatment effect. We assessed the association of blinded randomized pill prescription adherence with vascular outcomes after ischemic stroke.

We analyzed the Vitamin Intervention for Stroke Prevention (VISP) study database. VISP was a double-blind randomized trial, designed to determine whether high doses of vitamins (vs. low doses) would reduce recurrent stroke risk in 3,680 participants over a 2-year period. We examined the independent association of adherence with a composite endpoint (stroke, myocardial infarction, death).

Among 3,357 (91%) subjects with complete data, women, non-White persons, current smokers, those not on statins and those without a history of coronary artery bypass surgery were significantly less likely to be optimally adherent. Over the trial, persons who adhered well to treatment were less likely to experience the combined outcome than those who adhered poorly (13.4 vs. 20.6%, p < 0.0001). After multivariable analysis using various adherence measures, there were no significant differences between >or=80% vs. <80% adherence, but compared to <65% adherence, pill adherence levels of >or=90 to <99% (HR 0.56, 95% CI = 0.34-0.91; p = 0.02) and >or=99% (HR 0.46, 95% CI = 0.29-0.73; p = 0.001) were associated with lower occurrence of the combined outcome at 18 months.

Long-term excellent adherence to non-specific pill prescription among ischemic stroke patients is independently associated with lower vascular risk, and is likely a marker of overall healthy behavior that may be helpful in targeting stroke patients with unhealthy practices.