Introduction
Cardiovascular diseases (CVD) are responsible for nearly half of all
deaths globally (1). Minimizing the impact of CVD and related
disabilities is a major challenge and aspirin is the oldest and most
reliable drug for this purpose (2). It is an indispensable drug in the
secondary prevention of CVD (2). The net benefit is well established and
supported by a large body of evidence for secondary prevention patients
(3-5). However, there is no clear consensus on whom aspirin therapy is
appropriate for the primary prevention of CVD.
The 2016 European Society of Cardiology (ESC) guidelines on CVD
prevention did not recommend aspirin therapy in primary prevention due
to increased risk of bleeding (6). While this recommendation includes
both patients with and without diabetes mellitus (DM) in European
guidelines, the American Diabetes Association (ADA) 2018 guidelines
recommend aspirin therapy in patients with DM aged 50 years or older
with at least one additional CVD risk factor, without increased risk of
bleeding (7). In parallel, 2016 United States Preventative Services Task
Force (USPTF) (8) and 2019 American College of Cardiology/ American
Heart Association (ACC/AHA) guidelines on the primary prevention of CVD
states that aspirin (75-100 mg/day) might be used in selected patients
aged 40 to 70 who have high CVD risk but not increased bleeding risk
(9).
Recently, three large-scale randomized controlled trials evaluated the
use of aspirin in the primary prevention of CVD. These trials provided
further evidence for the use of aspirin in primary prevention. The
Aspirin in Reducing Events in the Elderly (ASPREE) trial enrolled
elderly patients (10), the Aspirin to Reduce Risk of Initial Vascular
Events (ARRIVE) trial enrolled patients with moderate to high CVD risk
(11), and the A Study of Cardiovascular Events iN Diabetes (ASCEND)
trial enrolled patients with DM (12). While ARRIVE and ASPREE trials
showed no benefit in terms of CVD risk reduction, only the ASCEND trial
indicated a lower rate of major CV events, but this effect was
attenuated by a higher rate of major bleeding. There was no all-cause
mortality benefit in these trials (9-11). However, indications,
prescription patterns, and appropriateness of aspirin use have not been
well investigated with randomized or observational studies in Turkey.
Therefore, the Appropriateness of Aspirin Use in Medical Outpatients: A
Multicenter, Observational Study (ASSOS) aims to investigate the
potential misuse of aspirin in both primary and secondary prevention
patients. The ASSOS is the largest multicenter domestic trial regarding
this topic. The use of aspirin therapy was evaluated taking into account
the risk of CVD and bleeding in this real-world trial.