Medications previously designated "high-risk" were implicated in only 1.2 percent of hospitalizations, the study found.Working with a nationally representative database, CDCresearchers identified more than 5,000 cases of drug-related adverse events that occurred among people aged 65 and older from 2007 to 2009 and used that to make their estimates for the whole population.
Nearly half (48 percent) of the hospitalizations occurred among adults 80 and up, according to the study, published in the Nov. 24 issue of the New England Journal of Medicine. Nearly two-thirds (66 percent) were the result of unintentional overdoses.
The four medications, used alone or together, most often cited:
The blood thinning medication warfarin (Coumadin, Jantoven), which is used to treat blood clots, was involved in 33 percent of emergency hospitalizations.
Insulin, used to control blood sugar in diabetes patients, was involved in 14 percent of cases.
Antiplatelet drugs such as aspirin and clopidogrel (Plavix), which are used to prevent blood clots, were involved in 13 percent of cases.
Oral hypoglycemic agents -- diabetes medications taken by mouth -- were involved in 11 percent of cases.