EvidenceAlerts

Abdelaziz HK, Saad M, Pothineni NVK, et al. Aspirin for Primary Prevention of Cardiovascular Events. J Am Coll Cardiol. 2019 Jun 18;73(23):2915-2929. doi: 10.1016/j.jacc.2019.03.501. (Systematic review)
Abstract

BACKGROUND: The efficacy and safety of aspirin for primary prevention of cardiovascular disease (CVD) remain debatable.

OBJECTIVES: The purpose of this study was to examine the clinical outcomes with aspirin for primary prevention of CVD after the recent publication of large trials adding >45,000 individuals to the published data.

METHODS: Randomized controlled trials comparing clinical outcomes with aspirin versus control for primary prevention with follow-up duration of =1 year were included. Efficacy outcomes included all-cause death, cardiovascular (CV) death, myocardial infarction (MI), stroke, transient ischemic attack (TIA), and major adverse cardiovascular events. Safety outcomes included major bleeding, intracranial bleeding, fatal bleeding, and major gastrointestinal (GI) bleeding. Random effects DerSimonian-Laird risk ratios (RRs) for outcomes were calculated.

RESULTS: A total of 15 randomized controlled trials including 165,502 participants (aspirin n = 83,529, control n = 81,973) were available for analysis. Compared with control, aspirin was associated with similar all-cause death (RR: 0.97; 95% confidence interval [CI]: 0.93 to 1.01), CV death (RR: 0.93; 95% CI: 0.86 to 1.00), and non-CV death (RR: 0.98; 95% CI: 0.92 to 1.05), but a lower risk of nonfatal MI (RR: 0.82; 95% CI: 0.72 to 0.94), TIA (RR: 0.79; 95% CI: 0.71 to 0.89), and ischemic stroke (RR: 0.87; 95% CI: 0.79 to 0.95). Aspirin was associated with a higher risk of major bleeding (RR: 1.5; 95% CI: 1.33 to 1.69), intracranial bleeding (RR: 1.32; 95% CI: 1.12 to 1.55), and major GI bleeding (RR: 1.52; 95% CI: 1.34 to 1.73), with similar rates of fatal bleeding (RR: 1.09; 95% CI: 0.78 to 1.55) compared with the control subjects. Total cancer and cancer-related deaths were similar in both groups within the follow-up period of the study.

CONCLUSIONS: Aspirin for primary prevention reduces nonfatal ischemic events but significantly increases nonfatal bleeding events.

Ratings
Discipline Area Score
Family Medicine (FM)/General Practice (GP) 6 / 7
General Internal Medicine-Primary Care(US) 6 / 7
Public Health 6 / 7
Internal Medicine 6 / 7
Cardiology 6 / 7
Comments from MORE raters

Cardiology rater

This should settle the debate.

Cardiology rater

Very important addition to the debate on aspirin for primary prevention. This study is consistent with the 2019 ACC/AHA guidelines.

Internal Medicine rater

This is all really about shared informed decision-making. The value of articles like this is that it gives us absolute numbers with which we can discuss harms and benefits leading to the informed part of a shared informed decision.

Public Health rater

I think this is really important to know. I just wonder how many people out there might have missed it. It was pretty well broadcasted within the medical world and just about everywhere else.

Public Health rater

Aspirin is being widely used for primary prevention of cardiovascular disease. Aspirin is of well well established benefit for primary prevention of stroke and TIAs. Also, ASA is also established for primary prevention of cancer incidence and mortality. The data are less clear for ASA in primary prevention of cardiovascular disease (although in my experience, widely used for his purpose, including by me!).
Comments from EvidenceAlerts subscribers

Dr. Amanda Burls (7/6/2019 7:49 PM)

Just providing relative risks in the abstract doesn't allow one to make meaningful comparisons. The NNT or NNH or simple absolute risks would have been more helpful.