Aspirin treatment and risk of first incident cardiovascular diseases in patients with type 2 diabetes: an observational study from the Swedish National Diabetes Register

OBJECTIVES: To investigate the benefits and risks associated with aspirin treatment in patients with type 2 diabetes and no previous cardiovascular disease (CVD) in clinical practice. DESIGN: Population-based cohort study between 2005 and 2009, mean follow-up 3.9 years. SETTING: Hospital outpatient clinics and primary care in Sweden. PARTICIPANTS: Men and women with type 2 diabetes, free from CVD, including atrial fibrillation and congestive heart failure, at baseline, registered in the Swedish National Diabetes Register, with continuous low-dose aspirin treatment (n=4608) or no aspirin treatment (n=14 038). MAIN OUTCOME MEASURES: Risks of CVD, coronary heart disease (CHD), stroke, mortality and bleedings, associated with aspirin compared with no aspirin, were analysed in all patients and in subgroups by gender and estimated cardiovascular risk. Propensity scores were used to adjust for several baseline risk factors and characteristics at Cox regression, and the effect of unknown covariates was evaluated in a sensitivity analysis. RESULTS: There was no association between aspirin use and beneficial effects on risks of CVD or death. Rather, there was an increased risk of non-fatal/fatal CHD associated with aspirin; HR 1.19 (95% CI 1.01 to 1.41), p=0.04. The increased risk of cardiovascular outcomes associated with aspirin was seen when analysing women separately; HR 1.41 (95% CI 1.07 to 1.87), p=0.02, and HR 1.28 (95% CI 1.01 to 1.61), p=0.04, for CHD and CVD, respectively, but not for men separately. There was a trend towards increased risk of a composite of bleedings associated with aspirin, n=157; HR 1.41 (95% CI 0.99 to 1.99). CONCLUSIONS: The results support the trend towards more restrictive use of aspirin in patients with type 2 diabetes and no previous CVD. More research is needed to explore the differences in aspirin's effects in women and men.