A large meta-study from a team of UK researchers has examined data from over a dozen different clinical trials to conclude that the dangers of daily aspirin use may outweigh any potential benefits for individuals that are generally healthy.

Aspirin is inarguably an amazing drug. It was officially isolated as a compound, and dubbed aspirin, back in 1899 but its natural precursor, often derived from willow trees, has been used medicinally in various cultures for thousands of years. In addition to its common uses, in the second half of the 20th century the drug became known as an effective preventative medicine for heart attacks, and by the late 1980s daily use was regularly recommended by physicians, especially for older patients.

Over recent years the safety of this general recommendation has been questioned by some researchers suggesting aspirin increases a person's risk of suffering serious bleeding events, and a new meta-study backs up this concern concluding the increase in bleeding risk most likely eliminates any cardiovascular benefits.

The new research pooled together data from 13 trials, comprising over 160,000 subjects. While it was found that aspirin use did indeed reduce the incidence of cardiovascular events compared to those subjects that did not take aspirin, it also raised the incidence of major bleeding events.

Kevin McConway, a researcher from Open University who did not work on this current study, sums up the results explaining that out of 10,000 healthy people, around 61 would normally suffer from heart attack or stroke without daily aspirin use, whereas the new research suggests only 57 would suffer the same problems if taking aspirin.

"Only 4 fewer in 10,000, but that still has some importance given how common such diseases are and how serious cardiovascular disease is," says McConway. "The downside is the increase in major bleeding events, including bleeding inside the skull and brain or major bleeds in the stomach or gut."

In comparison to these potential protective benefits, McConway suggests out of 10,000 healthy subjects we would normally see about 16 suffer an adverse bleeding event in a given year. This number increases to 23 when considering aspirin usage. So the general conclusion is, comparing the risks to the benefits, aspirin may do more harm than good if a person is otherwise healthy and not at a high risk of cardiovascular disease.

Lead author on the new study, Sean Zhang hopes this new research will help clarify when patients should or shouldn't administer aspirin as a preventative medicine.

"This study demonstrates that there is insufficient evidence to recommend routine aspirin use in the prevention of heart attacks, strokes and cardiovascular deaths in people without cardiovascular disease," says Zhang. "Aspirin use requires discussion between the patient and their physician, with the knowledge that any small potential cardiovascular benefits are weighed up against the real risk of severe bleeding."

The new study was published in the journal JAMA.