Common antibiotic linked to sudden heart deaths

An antibiotic used by millions of people in the UK has been linked to an increased risk of dying from heart problems, a study has found

A study found there were an extra 37 cardiac deaths per one million courses of clarithromycin compared with penicillin  Photo: Alamy

An antibiotic taken by millions of patients has been linked to heart deaths prompting researchers to call for an 'urgent' evaluation.

A Dutch study found that people taking clarithromycin were 76 per cent more likely to die than those taking penicillin and the risk was greater in women who were more than twice as likely to die.

Clarithromycin is used for respiratory infections and 2.2m doses were prescribed in 2013 in England.

Experts said the findings do not prove that the drug is dangerous or should be withdrawn and instead further research is needed to establish if there was a difference in the types of people prescribed clarithromycin compared with those receiving other antibiotics.

The study, published online in the British Medical Journal, found there were an extra 37 cardiac deaths per one million courses of clarithromycin compared with penicillin in the Dutch population studied.

The drug is known to extend the electrical activity in the lower sections of the heart which can increase the risk of potentially fatal rhythm disturbances

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British experts said for this reason is it not recommended in people with a known heart rhythm problem.

Lead author of the study Henrik Svanström, a statistician in the Department of Epidemiology Research, at the Statens Serum Institute in Copenhagen, wrote in the journal: "This large cohort study found a significantly increased risk of cardiac death associated with clarithromycin. No increased risk was seen with roxithromycin. Given the widespread use of clarithromycin, these findings call for confirmation in independent populations

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"Interpretation of the clinical importance of this finding, if confirmed, is delicate.

"One the one hand, the absolute risk is small, so this finding should probably have limited, if any, effect on prescribing practice in individual patients (with the possible exception of patients who have strong risk factors for drug induced arrhythmia).

"On the other hand, clarithromycin is one of the more commonly used antibiotics in many countries and many millions of people are prescribed this drug each year; thus, the total number of excess (potentially avoidable) cardiac deaths may not be negligible. These factors need to be considered when assessing the overall benefit/risk profile of macrolides (clarithromycin specifically), an important area for future work by, for example, regulatory agencies and other public health officials."

The team compared data from 160,297 courses of clarithromycin, 588,988 of roxithromycin and 4,355,309 of penicillin V prescribed for seven days to Danish adults aged 40-74 years from 1997 to 2011.

There were a total of 285 cardiac deaths, 18 of which occurred during use of clarithromycin and 32 during use of roxithromycin.

After adjusting for factors such as age and sex and their underlying heart risk and other medicines they calculated that there were 37 deaths per one million courses of clarithromycin.

Prof Kevin McConway, professor of Applied Statistics at The Open University, said: “It’s important to realise that the researchers are not calling for clinicians to stop prescribing clarithromycin, but instead for more data from different populations of patients, to see whether or not their finding can be confirmed. They have good reasons for that cautious conclusion.

“The risk of such a death when taking one of these antibiotics is very small.

"On the researchers’ own analysis, the cardiac death rate on clarithromycin could plausibly be anywhere between eight per cent and 185 per cent higher than the rate on penicillin V. So they concluded that the death rate was higher on clarithromycin, but they couldn’t be very sure how much higher. And in any case a death rate that’s just a bit higher than a very small death rate will still be very small.

"Since in any case the cardiac death rate while on these drugs is very small, this isn’t a risk that I personally would worry about anyway.”

Dr Mike Knapton, Associate Medical Director at the British Heart Foundation, said: “All medications can come with side effects, which is why your doctor will always weigh up the risks before prescribing drugs to patients.

“Health professionals already know to exercise caution when prescribing clarithromycin in patients who have, or may be predisposed to Long QT syndrome – a condition that can cause sudden cardiac death. This study shows that they should continue to follow that advice.

“More research is now needed to understand the effect of this antibiotic on the wider population. The bottom line is no one should be taking antibiotics unless they absolutely have to and doctors should give careful consideration before prescribing them. If you are taking clarithromycin at the moment, you should not stop without discussing this further with your GP.”

Dr Andrew Seaton, a consultant in Infectious Diseases and General Medicine at NHS Greater Glasgow and Clyde Health Board, said the effect of the drug on the QT interval is known and is already used with caution in people at risk of this condition.

He added: “Clarithromycin is used to treat bacterial upper and lower respiratory tract infections. As we have all heard recently, antibiotics can be overused and may be unnecessarily prescribed – in conditions where antibiotics are required, alternatives to clarithromycin should be considered when other risk factors for QT prolongation are evident.”

Dr Tim Chico, a reader in Cardiovascular Medicine and consultant cardiologist at University of Sheffield, said: “It would be a mistake to conclude that this study proves clarithromycin increases the risk of cardiac death. A slightly higher number of patients died while or soon after taking clarithromycin compared with penicillin but this may have been due to other differences between these patients, who the study authors acknowledge were different in several important ways.

"There are many good reasons to avoid unnecessary use of antibiotics such as trying to reduce development of bacteria that are resistant to treatment but I do not think that this study calls for a change in whether patients are prescribed clarithromycin.”

Kieran Hand, a pharmacist at Southampton General Hospital said the study reinforces the need to prescribe antibiotics sparingly and that all drugs carry a risk.

He said: "All antibiotics carry a small risk of a serious complication and simply switching patients from clarithromycin to penicillin will not solve the problem as there is a risk of a serious allergic reaction in some patients.

"Clarithromycin is often used in patients who think they have had an allergic reaction to pencillin. Serious allergic reactions are rare and often the patient has only had an upset tummy after penicillin and in those cases we are ruling out an effective group of drugs."

Source;  http://www.telegraph.co.uk/health/healthnews/11043045/Common-antibiotic-linked-to-sudden-heart-deaths.html