Do not PIMP my nursing home ride! The impact of Potentially Inappropriate Medications Prescribing on residents’ emergency care use

Nursing home residents often are poly-medicated, which increases their risks of receiving potentially inappropriate medications. This problem has become a major public health issue in many countries, and in particular in France. Indeed, high uses of potentially inappropriate medication prescriptions can lead to adverse effects that are likely to increase emergency room (ER) visits. However, there is a lack of empirical evidence on the causal relationship between the amount of use of potentially inappropriate medications and ER visit risks among nursing homes residents. Indeed, this question is subject to endogeneity issues due to omitted variables that simultaneously affect inappropriate medications prescriptions and ER use. We take advantage of the IDEM Randomized Clinical Trial (Systematic Dementia Screening by Multidisciplinary Team Meetings in Nursing Homes for Reducing Emergency Department Transfers) to overcome that issue. Indeed, randomization in the IDEM intervention group created exogenous variations in potentially inappropriate prescriptions, and was thus used as an instrument. Using an instrumental variable model, we show that over a 12-month period, a 1% increase in the share of potentially inappropriate medications spending in total medication spending leads to a 5.7 percentage point increase in residents’ ER use risks (p