The outcomes of clopidogrel therapy in patients with ACS in southern Tasmania

Vonna, A 2013 , 'The outcomes of clopidogrel therapy in patients with ACS in southern Tasmania', Research Master thesis, University of Tasmania.

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Abstract

$$Background:$$ Clopidogrel has become an essential component in the management of acute coronary syndromes (ACS); however there is a significant variability in patient outcomes in relation to rethrombosis and major bleeding. Australian data regarding the use and outcomes of clopidogrel therapy are limited.
$$Objectives:$$ Our study aimed to evaluate the rates of hospital readmission due to recurrent ACS or bleeding among patients with a first episode of ACS admitted to the Royal Hobart Hospital (RHH) and discharged taking clopidogrel, and to investigate the influence of a variety of factors including drug interactions, adherence and persistence with clopidogrel therapy, and cytochrome P450 genotype on the risk of readmission.
$$Method:$$ In a retrospective observational study, patients discharged between 1 July 2007 and 31 December 2009 were identified and followed for 18 months for readmissions due to recurrent ACS or bleeding. Patients were then surveyed regarding their attitudes to, and experiences of, clopidogrel therapy; community pharmacy dispensing records were used to assess adherence and persistence; and cytochrome P450 2C19 genotypes were determined. Adherence was defined as the degree in which patients take medications as prescribed, while persistence referred to whether the patient stayed on therapy for the duration planned. Statistical analysis was then used to determine the relative influence of each potential contributing factor on the risk of readmission due to recurrent ACS and bleeding.
$$Results:$$ Thirty-three of the 297 patients identified (11.1%) were readmitted to the RHH for recurrent ACS and nine (3.0%) for bleeding. None of the factors investigated significantly influenced the likelihood of readmission for ACS. Patients taking antiplatelet agents plus other medications that increase the risk of bleeding had a higher risk of a bleeding-related readmission (p < 0.05). Though the proportion of patients who were persistent with clopidogrel therapy was high (73%), the rate of early discontinuation of the therapy was concerning (27%). The proportion of patients who were adherent was also low (55%). Patients with CYP450 2C19*17 (19 out of 50 patients) demonstrated an increased risk of bleeding compared to the non-carriers (16% vs 0%, p= 0.022).Conclusions: Compared to previous studies, our study cohort demonstrated a slightly higher readmission rate due to ACS but a lower rate of bleeding. Concerns remain regarding the concomitant use of drugs that increase the risk of bleeding, as well as the use of gastroprotective agents in patients with a high risk of haemorrhage. The level of adherence and persistence with clopidogrel therapy was also concerning. Larger studies are required to determine the relationship between CYP450 2C19 status and the risk of major bleeding.

Item Type: Thesis - Research Master Vonna, A drug therapy, acute coronary syndrome, adherence, pharmacogenomics Copyright 2013 the author MPharm View statistics for this item