Furthermore, the increase in adverse events appears highest in the first 90 days after stopping the thienopyridine antiplatelet clopidogrel in both medically and PCI-treated ACS patients (incidence rate ratios 1.98 and 1.82 respectively). This study did not explore the reasons why patients stopped taking thienopyridine drug therapy. Even assuming that adherence to dual antiplatelet post-PCI medication is good, stent thrombosis
occurs in 0.5–2% of elective and up to 6% of ACS patients who are given a stent. Thus the risk of a cardiovascular event due to stent thrombosis increases with increasing non-adherence. In a further study investigating the prevalence and predictors of thienopyridine antiplatelet discontinuation post-myocardial infarction (MI) in patients treated with BMS, almost one in AZD6244 purchase seven patients discontinued thienopyridine by day 30. This was associated with a significantly higher increase in mortality over the next 11 months (7.5 compared with 0.7%, P<0.0001). Those who discontinued were less educated, not married, had previous co-morbidities and were generally older. What the study did not illustrate, beyond interpretation of demographic data, were the reasons why individual patients had stopped their medication. However, it does allow for hypotheses to be drawn from the results, which can be explored further using qualitative techniques. The effect of medication cost in relation to adherence has been studied by Ko et al. in 10 000 patients, all of whom were above the age of 65 selleck and had received either BMS or DES as PCI in Canada. Thienopyridine antiplatelet therapy was given to patients at low cost. This
study found that non-adherence was highest in the patients who had to pay the most for their prescription. The group who received free medication were almost 70% more likely to order prescriptions, thus implying a prohibitive effect of healthcare charges and supporting the argument that patients who have to pay for medication are less likely to access it. Non-adherence increased clonidine the risk of mortality. The investigators also found that patient adherence decreased with increasing time after the index event, suggesting that a degree of ambivalence manifests with time. The effect of adherence to statin therapy has also been investigated post-PCI. The relative risk reduction for those on statin post-PCI was reported as 22% in the original trial. After analysis and adjusting for non-compliance, the relative risk reduction for major cardiac events was 32%, with the additional 10% relative risk reduction being due purely to good adherence to medication. Previous research has quantitatively characterised some aspects of medication adherence post-PCI. However, there has not been a detailed exploration of the patient-specific factors relating to such adherence.