Cardiovascular prophylaxis with aspirin: Costs of supply and management of upper gastrointestinal and renal toxicity

Aims: To determine the cost to the NHS of prescribed low-dose aspirin. Methods: This was a population based observational cohort study. Patients from Tayside Scotland (17 244 new users of dispensed aspirin each with 10 matched comparators) were included. A pragmatic analysis totalled costs from the start to end of the study and compared these with a matched cohort of aspirin nonusers to estimate excess costs. Fastidious analyses were done of subjects with no prior history of upper gastrointestinal (UGI) or renal disease where the cost that occurred during aspirin exposure, the 30 days following aspirin exposure and subsequent nonexposure was calculated adjusting for risk factors in each period. Results: Subjects took aspirin for only 1.18 of the 2.53 years follow-up (47% compliance). Aspirin use cost an additional £49.86 per year (pragmatic analysis) made up of £1.96 for aspirin tablets (4%), £5.49 for dispensing costs (11%), £24.60 for UGI complications (49%) and £17.81 for renal complications (36%). The costs for managing complications were substantially lower in the fastidious analysis (£2.66 for UGI complications and £2.92 for renal complications). Assuming that the antiplatelet trial meta-analysis is an accurate assessment of the benefits of aspirin, the costs of preventing one vascular event lay between £62 500 (primary prevention, pragmatic analysis) and £867 (secondary prevention, fastidious analysis). These costs may be underestimates due to the low compliance observed. Conclusions: Compliance with aspirin was poor. Serious adverse events were uncommon but despite this aspirin cost the NHS between 6 and 25 times the cost of aspirin tablets due to dispensing costs and the cost of managing adverse effects.