Pharmacoepidemiology
High Prevalence and Variable Duration of Potentially Clinically Relevant Drug-Drug Interactions Among U.S. Nursing Home Residents Laura A. Reich* Laura Reich Adam M. D’Amico Sarah D. Berry Lori A. Daiello Andrew R. Zullo
Background: Nursing home (NH) residents are at increased risk of drug-drug interactions (DDIs) due to multimorbidity and polypharmacy. Despite guidelines discouraging providers from concurrently prescribing medications that lead to DDIs, the extent of exposure to potentially clinically relevant DDIs among U.S. NH residents is largely unknown.
Objective: To determine the prevalence of potential DDIs among NH residents and the proportion of residents’ time exposed to these DDIs.
Methods: This observational study included Medicare fee-for-service beneficiaries aged ≥66 years living in NHs with observable prescription drug data in Medicare Part D claims between 2018 and 2020. We calculated the proportion of residents exposed to 91 potential DDIs identified from three expert consensus publications, as well as the proportion of time residents were exposed to each DDI. DDI exposure was defined as at least one day of concurrent use between orally administered medications.
Results: Among 485,251 NH residents, 61.6% were exposed to at least one potential DDI during 272,967 person-years of follow-up. Residents spent a combined 43.9% of their total NH time exposed to at least one DDI. Across the 91 potential DDIs, the median proportion of residents exposed to a DDI was 0.1% (IQR 0.01-2.0%), and residents were exposed to a DDI for a median of 0.04% of their time in the NH (IQR 0.003-1.0%). The most common DDI, “concomitant use of ≥3 centrally acting drugs,” was observed in 27.1% of residents, with 14.5% of residents’ total NH time spent exposed to the DDI.
Conclusion: Nearly two-thirds of NH residents were concurrently exposed to medications linked to potential DDIs, although the prevalence and exposure time associated with individual DDIs varied considerably. Because DDIs can be harmful even during brief exposure, future research should examine the role of DDI exposure duration on adverse drug events for the most prevalent potential DDIs among U.S. NH residents.