Represcription of Low-Dose Acetylsalicylic Acid After Discontinuation in Patients Receiving Treatment for Secondary Cardiovascular Disease Prevention in the UK

In this retrospective database study, carried out using The Health Improvement Network, a UK primary care database, we followed up patients who were prescribed low-dose acetylsalicylic acid (ASA) (75-300 mg/day) for the secondary prevention of cardiovascular disease in 2000-2007, and who discontinued therapy for a period of at least 90 days during that time (n = 11,565). We assessed the incidence of, and factors associated with, ASA represcription. Patients were followed up from the first day after their initial 90-day period of discontinuation (start date) until ASA represcription, death, or the end of the study period (31 December 2010). Hazard ratios for factors associated with represcription were calculated using Cox regression models. The cumulative incidence of ASA represcription was 85.2 % over the entire follow-up period, and 63.5 % of all represcriptions were received in the first 6 months after patients' start dates. Factors significantly associated with a reduced likelihood of ASA represcription included being aged 75-84 years, cardiovascular and gastrointestinal comorbidities (in particular, atrial fibrillation and high overall gastrointestinal risk), adverse drug reactions experienced during therapy, and use of gastroprotective or cardiovascular medications (most notably warfarin). Factors significantly associated with an increased likelihood of ASA represcription included obesity, diabetes mellitus, stable angina, depression, and use of non-steroidal anti-inflammatory drugs. In conclusion, approximately 85 % of patients who discontinued low-dose ASA therapy were subsequently represcribed ASA during the study period. Comorbidities and comedication use affected represcription rates.