(British Medical Journal) -- Ibuprofen and other commonly used painkillers for treating inflammation may increase the risk of heart attack, says a study in this weeks BMJ.

Patients should not stop taking the drugs involved non-steroidal anti-inflammatory drugs (NSAIDS) but further investigation into these treatments is needed, say the authors.

In the biggest study of its kind to date, researchers identified 9,218 patients across England, Scotland and Wales who suffered a heart attack for the first time over a four year period. Patients ranged in age from 25 to 100.

Researchers looked at the prescribing patterns for these patients, tracking whether and when they had been prescribed NSAIDS. NSAIDS are commonly prescribed to relieve inflammation and pain, and include ibuprofen, diclofenac, naproxen, celecoxib and rofecoxib, plus a host of other less commonly prescribed anti-inflammatories.

The findings were adjusted to allow for several other heart attack risk factors including age, obesity, and smoking habits. Importantly, they also adjusted for whether the patient already suffered from heart disease, or whether they were being prescribed aspirin.

Researchers found that for those prescribed NSAIDS in the three months just before the heart attack, the risk increased compared with those who had not taken these drugs in the previous three years. For ibuprofen, the risk increased by almost a quarter (24%), and for diclofenac it rose by over a half (55%).

The newer generation of anti-inflammatories -- COX-2 inhibitors -- were also associated with increased rates of first-time heart attack.

Those prescribed the drugs in the preceeding three months were at 21% higher risk of heart attack if taking celecoxib, and 32% increased risk if taking rofecoxib.

Since this study was concluded rofecoxib has already been withdrawn following concerns over heart attack risk. This is all the more important for the impact of this study on patients, say the authors, since those previously taking rofecoxib will have already turned to the other anti-inflammatories in greater numbers.

The most significant findings were for the drugs ibuprofen, diclofenac and rofecoxib, say the authors.

In terms of numbers needed to harm in the 65 and over age group, for those taking diclofenac, one extra patient for every 521 patients was likely to suffer a first-time heart attack. For rofecoxib the figure was one patient for every 695 patients; and for ibuprofen one patient for every 1005 patients was at risk.

Given the high prevalence of the use of these drugs in elderly people and the increased risk of myocardial infarction [heart attack] with age, the relatively large number of patients needed to harm could have considerable implications for public health, say the authors.

The nature of this report an observational study may make it prone to other explanations for the findings, say the authors. However, enough concerns exist to warrant a reconsideration of the cardiovascular safety of all NSAIDS, they conclude.

A separate editorial in the BMJ urges caution when interpreting the study, and suggests that some aspects of the findings could be explained by other factors.