Daily low-dose aspirin not seen to lower CV deaths

A RECENT study by Yasuo Ikeda, M.D. and colleagues about the effects of once-daily, low-dose aspirin on the reduction of the total number of cardiovascular events on older Japanese patients shows a once-daily, low-dose aspirin intake does not lower the risks of CV death and other adverse outcomes in older patients with certain risk factors.

While aspirin caused a substantial reduction in the incidence of nonfatal heart attack and transient ischemic attack, it increased the risk of extracranial hemorrhage requiring transfusion or hospitalization. Although there is no consistent evidence about the benefit of aspirin in the primary prevention of cardiovascular events, it is well proven that the drug is useful in secondary prevention, including among Japanese patients. A growing body of evidence also suggests aspirin is beneficial in preventing colorectal and other cancers, and cancer recurrence.  

The study led by Professor Ikeda of the Waseda University in Tokyo, Japan, compared the effects on the total number of cardiovascular events death from CV causes, nonfatal heart attack or stroke of a once-daily low-dose aspirin intake as opposed to no aspirin at all among elderly Japanese patients. It involved 14,464 patients aged 60 to 85 years old randomized to aspirin (100 mg/d) or no aspirin in addition to ongoing medications. The patients, who were recruited by primary care physicians at 1,007 clinics in Japan, have hypertension, diabetes mellitus, or dyslipidemia.

The study appeared in JAMA and released to coincide with the presentation at the American Heart Association’s Scientific Sessions 2014.

Although the study was terminated early by the data monitoring committee after a median follow-up of 5.02 years due to likely futility, the researchers found no significant statistical difference between the two groups in time to the primary end point, which was a composite of death from cardiovascular causes, nonfatal stroke, or nonfatal heart attack. At 5 years after randomization, the cumulative primary event rate between in the aspirin group (2.77%) and those in the no aspirin group (2.96%) was similar.

Projections the World Health Organization place annual global mortality due to cardiovascular diseases, including heart attack and stroke, at 25 million by 2030. In Japan, a recent study on trends in cardiovascular diseases indicated a sharp rise in cases of glucose intolerance, hypercholesterolemia, and obesity from 1960 to 2000 linked most likely to the growing adoption of Western diets and lifestyles. The study estimates that 32% of the Japanese population will be 65 years or older by 2030. The expanding aging population in the country alerts to the need to prevent atherosclerotic cardiovascular diseases.

The accompanying editorial from J. Michael Gaziano, M.D., M.P.H., of the Veterans Affairs Boston Healthcare System, Brigham and Women’s Hospital, Harvard Medical School, Boston, and JAMA associate editor, and Philip Greenland, M.D., of the Northwestern University Feinberg School of Medicine, Chicago, and senior editor at JAMA, notes that the findings add to the body of evidence that should help people address the issue of when to use aspirin to prevent vascular events.  

The decision on the drug to use involves evaluating the individual risk-to-benefit and should be discussed by the clinician and patient. Patients at high short-term risk due to an acute vascular event and those undergoing certain vascular procedures will benefit from taking aspirin. Patients with any evidence of vascular disease should be given daily aspirin. Those with a very low risk of vascular events will be ill advised to take aspirin for the prevention of vascular events, even at low dose.

“However, some individuals who do not have overt vascular disease will have risk levels that approach those of patients with CVD (such as patients with multiple risk factors). It remains likely that there is some level of risk of CVD events that would result in a positive trade-off of benefit and risk for the use of aspirin, but the precise level of risk is uncertain,” according to the editorial.