Objectives A number of instruments are used to identify potentially inappropriate medications (PIMs) in the elderly. In this study we identify PIMs in elderly patients and aim to compare three different instruments used to assess PIMs.

Methods In this prospective cohort study, we compared medications of elderly patients against three commonly used instruments: Beers’ list, PRISCUS and STOPP/START, at the point of hospital admission and discharge in the nephrology clinic of Kosovo’s largest hospital. Readmission risk was evaluated using the LACE Index and correlations with the number of PIMs and PIMs criteria were analysed.

Results Of 184 patients admitted to the nephrology clinic, 84 met study inclusion criteria. Patients had a median of three drugs at admission and four at discharge. Hospital readmission risk was high with median LACE Index being 11 (63% of patients). A higher number of PIMs was associated at the point of discharge compared with admission for all three tools (Beers’ list: 29% vs 38 %, P=0.04; STOPP/STRART: 20% vs 23%, P<0.001; PRISCUS list: 12% vs 21%, P<0.001). The number of drugs at admission predicted the number of PIMs at discharge only when using Beers' criteria (P=0.006). At discharge, each increase in medication was associated with an increase in PIMs based on Beers’ [0.134; (P=0.007)] and STOPP/START criteria [0.130; (P=0.005)]. Nitrofurantoin was the main PIM identified with Beers’ and PRISCUS list in comparison to proton- pump-inhibitors being the most prevalent agents identified with STOPP/START criteria.

Conclusions There are differences when using Beers’ criteria, STOPP/START criteria and PRISCUS list during identification of PIMs in elderly patients with high readmission risk. These differences should be considered when identifying PIMs in hospital settings.