Fifteen percent of all hospitalized patients experience at least one adverse drug reaction during their stay, and each ADR adds about 0.25 days onto the length of stay, according to Munir Pirmohamed and colleagues at the University of Liverpool.
To reach this conclusion, the scientists tracked the hospital stays of 3,695 consecutive patients admitted to 12 hospital wards during a 6-month stretch in 2005.
They reviewed charts to assess causality, severity and preventability, and performed multivariate analysis to identify ADR risk factors.
In all, 545 patients experienced at least one ADR. The report is in Plos One.
The most common ADRs included bleeding, constipation, confusion, renal problems, and nosocomial infections involving Clostridia, Staph and other potentially life-threatening bacteria. Half of all ADRs were felt to be definitely or possibly preventable.
The most commonly offending drugs were narcotic analgesics, anticoagulants and diuretics.
The number of drugs being taken by a patient turned out to be the most significant predictor of ADRs, with each additional medication multiplying the risk by about 14%.
Elderly people, who tend to be taking many medications, were therefore found to be at high risk for ADRs.
“Our results show that the overall burden of ADRs on hospitals is high and therefore new methods of intervention are needed to reduce this,” Pirmohamed told BurrillReports.
“We are currently looking at…ways of improving the safety of medicines, including increased monitoring…and identification of genetic factors that increase the risk of…adverse effects,” he added.
Other groups, particularly Boston’s Institute for Healthcare Improvement have made progress in this area. Even so, IHI estimates there are as many as 15 million incidents of medical harm each year in US hospitals.