Medication regimen complexity and prevalence of potentially inappropriate medicines in older patients after hospitalisation.

Background There is a relative paucity of information to characterise potential changes in medication regimen complexity and prevalence of prescribing of potentially inappropriate medications after hospitalisation, both in Australia and elsewhere. Objective To evaluate medication regimen complexity and the prevalence of potentially inappropriate medications before and after admission to hospital. Setting General medical units of a tertiary care hospital in Australia. Methods Retrospective cohort study of patients aged 65 years and above. Medication complexity was measured by using the Medication Regimen Complexity Index (MRCI). Main outcome measure The primary outcome was the change in the Medication Regimen Complexity Index for all prescribed medications after hospitalization. Results A convenience sample of 100 patients was included in the study. There was a significant change in the mean medication complexity score (as measured using the MRCI), increasing from 29 at the time of admission to 32 at the time of discharge (p < 0.05). Factors such as baseline medication regimen complexity (pre-admission MRCI) and length of stay in the hospitals appear to influence the change in medication complexity. However, the proportion of patients prescribed at least one potentially inappropriate medicine (PIM) decreased significantly, from 52% pre-hospitalization to 42% at discharge (p = 0.04). Conclusions Relative to the time of admission, overall medication complexity increased and the proportion of patients who were prescribed PIMs decreased after hospitalisation.