August 29, 2012

One in Five Prescriptions for Elderly Patients
Is Inappropriate, Study Finds

Amsterdam, The Netherlands—A ubiquitous antihistamine and a tricyclic antidepressant in use for more than 50 years are the most common medications prescribed inappropriately to older patients that also created high risk for adverse events, according to a Dutch review of English-language studies of medication use in the elderly.

According to the study, published recently in the open-access journal PLoS ONE,  diphenhydramine and amitriptyline are the most common inappropriately prescribed medications with high-risk adverse events, while propoxyphene and doxazoxin are the most commonly prescribed medications with low-risk adverse events.

Overall, the review found that about one in five prescriptions to elderly people is inappropriate, and the authors suggest that medications falling into that category are “good candidates for being targeted for improvement, e.g. by computerized clinical decision support.”

For the study, researchers from the Academic Medical Center in Amsterdam systematically searched OvidMEDLINE and OvidEMBASE from 1950 and 1980, respectively, to March 2012. Two independent reviewers also screened and selected primary studies published in English that measured appropriate and inappropriate primary care prescriptions to the elderly, defined as those older than 65 years.

Over the 19 studies reviewed, the median rate of inappropriate medication prescriptions (IMP) was found to be 20.5%. Medications with the largest median rate of inappropriate medication prescriptions were propoxyphene at 4.52%, doxazosin at 3.96%, diphenhydramine at 3.30% and amitriptyline at 3.20%.

The authors note that up to 35% of high-risk older outpatients develop preventable adverse drug events. One reason is inappropriate prescriptions, which the authors define as introducing “a significant risk of an adverse drug related event when there is evidence for an equally or more effective alternative medication” or “the failure to achieve the optimal quality of medication use.”

That can include underprescribing, misprescribing, or overprescribing, according to the study, which points out that among factors that can increase the risk to the elderly are physiological changes such as reduction in renal and hepatic function.

U.S. Pharmacist Social Connect