Clopidogrel Resistance in Patients With Recurrent Ischaemic Stroke on Dual Antiplatelet Therapy and Its Economic Impact in a Lower-Middle Income Country: A Single Centered Study in Southern India

OBJECTIVES: Recurrence of stroke is an important risk factor among population in developing world countries. One of the most important reasons postulated for recurrence of stroke and treatment failure being clopidogrel resistance due to genetic polymorphism. The study aims to analyze the prevalence of clopidogrel resistance in patients with recurrent stroke. Additionally, the objectives include analyzing switching of therapy, contributing risk factors and economic impact of therapy switching in patients with recurrent stroke.

METHODS: This retrospective study design allocated patients with recurrent stroke on dual antiplatelet agents from the neurology department over the past one year. The data regarding demographics, clinical details, medical history and economic considerations of patients were obtained from patient records. Gene polymorphism associations with clopidogrel resistance was determined by genotyping analysis. Chi-square test assessed the association between clopidogrel resistance and risk factors. Therapy switches were noted, follow-ups were done and analyzed economic impact on therapy changes.

RESULTS: A total of 40 patients were recruited into the study with males more than females and higher resistance rates exhibited by older age groups (>60 years). The clopidogrel resistance due to CYP2C19 polymorphism were prevalent in 70% of study population. No significant associations were found between age, sex, diabetes, dyslipidemia, smoking and alcohol consumption with clopidogrel resistance, except for hypertension (95% CI; p=0.027). All patients with polymorphisms were substituted with Ticagrelor and no fresh ischemic events found during follow-up. Potential economic burden was associated with switch of therapy among low-income population.

CONCLUSIONS: A higher incidence of Clopidogrel resistance was found in patients with recurrent stroke. Switching of therapy may be needed in clopidogrel non-responders to avoid risk of further ischemic events. This study emphasized the need for tailoring antiplatelet therapy considering clinical and economical aspect. Further research is needed to substantiate the multifarious impact of clopidogrel resistance.