Trends in Prevalence and Determinants of Potentially Inappropriate Prescribing in the United States: 2007 to 2012

OBJECTIVES: To estimate the prevalence and determinants of the use of potentially inappropriate medications (PIMs) in older U.S. adults using the 2012 Beers criteria. DESIGN: Retrospective cohort study in a random national sample of Medicare beneficiaries. SETTING: Fee-for-service Medicare beneficiaries from 2007 to 2012. PARTICIPANTS: U.S. population aged 65 and older with Parts A, B, and D enrollment in at least 1 month during a calendar year (N = 38,250 individuals; 1,308,116 observations). MEASUREMENTS: The 2012 Beers criteria were used to estimate the prevalence of the use of PIMs in each calendar month and over a 12-month period using data on diagnoses or conditions present in the previous 12 months. Generalized estimating equations were used to account for the dependence of multiple monthly observations of a single person when estimating 95% confidence intervals (CIs), and logistic regression was used to identify independent determinants of PIM use. RESULTS: The point prevalence of the use of PIMs decreased from 37.6% (95% CI = 37.0-38.1) in 2007 to 34.2% (95% CI = 33.6-34.7) in 2012, with a statistically significant 2% (95% CI = 1-3%) decline per year assuming a linear trend. The 1-year period prevalence declined from 64.9% in 2007 to 56.6% in 2012. The strongest predictor of PIM use was the number of drugs dispensed. Individuals aged 70 and older and those seen by a geriatrician were less likely to receive a PIM. CONCLUSION: From 2007 to 2012, the prevalence of PIM use in older U.S. adults decreased according to the 2012 Beers criteria, although it remains high, still affecting one-third each month and more than half over 12 months. The number of dispensed prescriptions could be used to target future interventions.