Renally inappropriate medications in elderly outpatients and inpatients with an impaired renal function

The purpose of this study was to investigate differences in the frequency of renally inappropriate medications (RIMs) in outpatient and inpatient among three institutions.

We collected prescription and renal function data for patients over 65 years of age from the drug department system. We selected 50 kinds of the most frequently used medicines which require dose adjustment according to a patient's renal function.

Outpatient RIM was seen in 611 cases (6.17%), and inpatient prescription RIM was seen in 317 cases (5.29%), showing a significant difference between the groups (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.02-1.35). However, in a multivariate analysis, when the renal function was included, that difference between outpatients and inpatients became insignificant (OR 1.16, 95% CI 0.98-1.37). The distribution of prescription with or without RIM in outpatient and inpatient settings depended on the CKD stage. Outpatients with a better CKD stage (stage 1-3) had a higher rate of RIM than inpatients, while patients with a worse CKD stage (stage 4 or 5) had a higher rate of RIM than outpatients.

The rate of RIM in outpatients tends to be high, and attention should be paid to RIM in inpatients with a severe CKD stage.