Long-term adherence to low-dose aspirin therapy for cardiovascular prevention in routine clinical practice in United Kingdom and Germany

Abstract

Abstract Background Low-dose aspirin is effective in the prevention of ischemic vascular events and studies have shown a preventative effect on colorectal cancer (CRC). However, adherence to therapy is likely an important factor for these benefits to be seen and non-adherence is associated with sub-optimal outcomes. Purpose To assess the long-term adherence to low-dose aspirin therapy in the primary and secondary cardiovascular (CVD) prevention population Methods This retrospective cohort study used data from United Kingdom (UK) – The Health Improvement Network Database and Germany (DE) – IQVIA Disease Analyzer and analyzed using an adaptation of Observational Health Data Sciences and Informatics (OHDSI) ATLAS Tool. Patients 18 years or older, with at least two prescriptions of low-dose aspirin (75–100mg) within the first year of index date during the study period between 2007 and 2018, and with at least 12 months of observation before and after the index date were included in the study. The patients with a CVD diagnosis or a CABG/PCI procedure before the index date or a prescription of dual antiplatelet at index date were classified as secondary CVD prevention. The remaining patients were classified as potential primary CVD prevention. The index date was first prescription of low-dose aspirin. Adherence was calculated using medication possession ratio (MPR) which is number of days of medication supplied within the refill interval divided by number of days in the refill interval. Long term adherence was divided in three categories namely patients with ≤2 years, 2-≤5 years, and 5-≤10 years of follow-up. Results The total number of patients receiving low-dose aspirin was 327,806 (183,089 in UK and 144,717 in DE with up to 10 years of follow-up). A total of 112,887 and 101,704 received low-dose aspirin for secondary CVD prevention; 70,202 and 43,013 potentially for primary CVD prevention in UK and DE, respectively. Median adherence to low-dose aspirin in UK and DE for patients with ≤2 years of follow-up was 88% and 80% for secondary CVD prevention, respectively; 84% and 74% for 2-≤5 years; and 75% and 59% for 5-≤10 years, respectively. Median adherence to low-dose aspirin in UK and DE for patients with ≤2 years was 76% and 75% for potential primary CVD prevention; 65% and 66% for 2-≤5 years; 49% and 49% for 5-≤10 years, respectively (Figure). Conclusion The long-term adherence to low dose aspirin was quite high with more than half the patients being adherent to their treatment. Overall, the adherence was higher in secondary compared to primary CVD prevention. The estimates for adherence might be underestimated due to potential over the counter use of low-dose aspirin. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Bayer AG