Trends of prescribing adherence of antiplatelet agents in Hong Kong patients with acute coronary syndrome: a 10-year retrospective observational cohort study

Objectives The objective of this study is to examine the temporal trend of antiplatelet prescribing pattern during index hospitalisation discharge in Hong Kong (HK) acute coronary syndrome (ACS) population. Design The study is a retrospective observational cohort study. Setting The study retrieved data from electronic health record from Hospital Authority (HA), HK. Participants The study included patients aged 18 years old or above, who were admitted to seven institutions under HA with diagnosis of ACS during 2008-2017. Primary and secondary outcome measures The primary outcome was the frequency of antiplatelet therapy prescription at the point of index hospitalisation discharge each year during 2008-2017. Association between demographics, baseline comorbidities, procedures and antiplatelet prescription were examined as secondary outcome using multivariate logistic regression model, with commonly used antiplatelet groups selected for comparison. Results Among the included 14 716 patients, 5888 (40.0%) discharged with aspirin alone, 6888 (46.8%) discharged with dual antiplatelet therapy (DAPT) with clopidogrel, and 973 (6.6%) discharged with DAPT with prasugrel/ticagrelor. Prescribing rate of aspirin alone decreased substantially from 56.8% in 2008 to 27.5% in 2017. Utilisation of DAPT with clopidogrel increased from 33.7% in 2008 to 52.7% in 2017. Use of DAPT with prasugrel/ticagrelor increased from 0.3% in 2010 to 15.3% in 2017. Compared with those prescribed with DAPT with clopidogrel, male patients (adjusted OR (aOR) 1.34, 95% CI 1.09 to 1.65), patients with non-ST-elevation myocardial infarction (aOR 2.50, 1.98 to 3.16) or ST-elevation myocardial infarction (aOR 3.26, 2.59 to 4.09), use of glycoprotein IIb/IIIa (aOR 3.03, 2.48 to 3.68) or undergoing percutaneous coronary intervention (aOR 3.85, 3.24 to 4.58) or coronary artery bypass graft (aOR 6.52, 4.63 to 9.18) during index hospitalisation, concurrent use of histamine-2 receptor antagonists (aOR 1.35, 1.10 to 1.65) or proton pump inhibitors (aOR 3.57, 2.93 to 4.36) during index hospitalisation discharge were more likely to be prescribed with DAPT with prasugrel/ticagrelor. Patients with older age (aOR 0.97, 0.96 to 0.97), diabetes (aOR 0.68, 0.52 to 0.88), chronic kidney disease (aOR 0.43, 0.22 to 0.85) or concurrent use of oral anticoagulant (aOR 0.16, 0.07 to 0.42) were more likely to received DAPT with clopidogrel. Conclusions Use of DAPT with prasugrel/ticagrelor was suboptimal yet improving during 2008-2017 in HK patients with ACS. Considering DAPT, predictors for clopidogrel prescription, compared with prasugrel/ticagrelor, were consistent with identified risk factors of bleeding.