Measure of inappropriate prescribing predicts risk of adverse drug events in older adults
Research Activities, September 2010, No. 361
Older patients who receive inappropriately prescribed drugs are at greater risk of suffering adverse drug events (ADEs) than patients who only receive appropriate drugs. ADE risk can be predicted with a measure of inappropriate drug prescribing, according to a new study. The researchers used a 6-criteria, modified version of the 10-criteria Medication Appropriateness Index (MAI) to create numerical scores for each medication a patient takes. Prescribed drugs are considered inappropriate if they have significant interactions with another drug the patient takes, if the drug's impact is affected by the patient's disease, or for other reasons (for example, if there is no indication for the drug's use, it is not effective for the indication, or it unnecessarily duplicates the action of another prescribed drug).
Among the 236 elderly veterans completing the study, 14.4 percent experienced an ADE. Only the modified MAI score significantly predicted ADE risk, but the score on the original MAI or another widely used measure of drug appropriateness (the Beers criteria) did not. The mean modified MAI score for these patients was 3.1. Every 1-point increase in the modified MAI score increased the patient's 3-month risk of an ADE by 13 percent.
The study used data from a sample of veterans aged 65 or older who were seen in the primary care clinics of the Iowa City Veterans Affairs Medical Center. Patients in the study received at least five prescription medications, lived in the general community (rather than a nursing home or other institution), and did not suffer from cognitive problems. MAI assessment of each patient's prescriptions was done by a trained clinical pharmacist. The investigators call for more research to confirm the association between the modified MAI scores and the risk of ADEs at 3 months.
The study was funded in part by the Agency for Healthcare Research and Quality (HS16094). More details are in "Inappropriate prescribing predicts adverse drug events in older adults," by Brian C. Lund, Pharm.D., M.S., Ryan M. Carnahan, Pharm.D., M.S., Jason A. Egge, Pharm.D., M.S., and others in the June 2010 The Annals of Pharmacotherapy 44(6), pp. 957-963.