Adverse drug reactions result in 250 000 UK admissions a year

More than a quarter of a million patients are admitted to hospital in the United Kingdom because of harmful effects after taking drugs, a BMA report estimates this week.

The report cites research from 2004 suggesting that these cases cost the NHS around £466m (€680m; $870m) a year.

The research, by Munir Pirmohamed and colleagues at the University of Liverpool, was based on an analysis of 18 820 admissions to hospital over six months, which found that 1225 were related to an adverse drug reaction (BMJ 2004;329: 15-9). Aspirin, diuretics, warfarin, and non-steroidal anti-inflammatory drugs were the drugs most commonly involved.

The authors of the BMA report extrapolated from these figures that the total for the UK could be 250 000.

In the UK adverse events must be reported to the Medicines and Healthcare Products Regulatory Agency (MHRA) under the yellow card scheme, which was set up in 1964 after use of thalidomide led to abnormalities among children of mothers who had taken the drug for morning sickness.

But the scheme is voluntary, and the report shows that the total number of adverse drug reactions being reported over the past 20 years has remained static at around 20 000 a year. The exception was the year 2000, when the total number of reports was 33 152. This was due to the introduction of the meningitis C vaccination campaign and a decision to allow nurses to report reactions.

Health professionals should see it as their “professional duty” to report to the scheme, the report says, and it is particularly important to report reactions in children, elderly people, and people with congenital abnormalities. But it says that many factors seem to stand in the way of reporting, such as lack of time, apathy, lack of awareness, confusion, and fear of legal reprisals.

Vivienne Nathanson, the BMA's head of ethics and science, said: “Clinical trials have limitations. And when a drug is first marketed its effectiveness may be well understood, but relatively little may be known about its safety in the population at large.”

“Doctors must make sure they report any suspected ADR [adverse drug reaction] and at the same time increase awareness among their patients about the reporting process,” she added.

Since January 2005 patients have been able to report to the scheme. Pharmacists joined in 1999 and nurses in 2000.

“Doctors should be reminded that the introduction of nurse and pharmacist reporting was meant to supplement the reports they made and not be a substitute for them,” the report says. It adds that hospital doctors in particular should be reporting more, given the high numbers of adverse drug reactions in hospitalised patients.

Hospital doctors fall behind GPs, who report the most, the report finds.