A recent study has found that one in seven patients experiences side effects from their medication while in hospital, and researchers are claiming that as many as half of these cases could be avoided.

In the largest prospective study looking at adverse drug reactions (ADRs) in UK hospital in-patients, published in the journal PLoS ONE, a team from Liverpool University assessed their incidence in 12 general hospital wards at the Royal Liverpool University Hospital over a six-month period in 2005.

They found that, out of the 3,695 patient episodes assessed for ADRs, 545 - or nearly 15% - experienced one or more of a wide range of reactions, such as constipation, bleeding, renal failure and even one directly-related death.

The drugs most frequently associated with ADRs were found to be diuretics, opioid-based painkillers, antibiotics and blood thinners, while those at greater risk from experiencing side effects were more likely to be older, female, taking more medicines and staying in hospital longer than patients without reactions.

However, the team stressed that the only significant link was found to be the number of drugs being taken by the patient, “with each additional medication multiplying the hazard of an ADR episode by 1.14”.

Aside from the negative impact of ADRs on the patient’s health, they also place a considerable strain on hospital resources. As well as the costs associated with extra treatments, the study found that drug side effects “directly increased” the duration of time in hospital in 26.8% of patients.

High cost
While acknowledging that their assumptions are based on a single hospital in the UK, the researchers estimate that ADRs cost the NHS in England more than £637 million a year, which equates to around £5,000 per hospital bed, and they stress that “effective intervention strategies are urgently needed to reduce this burden”.

Such strategies will likely be complex, the study authors stress, as a wide variety of different drugs were associated with a whole spectrum of ADRs, but they highlight using a computerised prescribing and monitoring system, taking pharmacists on ward rounds, and better prescribing education as possible intervention strategies.

Dr Jonathan Fielden, Chairman of the BMA's Consultants' Committee, said the findings are “further evidence of an international problem that requires healthcare teams, led by doctors, to ensure the safest prescribing practices possible”, and that it is “vital that doctors and patients understand the need to regularly review prescriptions and personally tailor treatment to clinical need.”