AbstractBackgroundPrevious studies on pharmacist‐led Home Medicines Review (HMR) have demonstrated positive associations of HMR and clinical outcomes. However, little is known about their impact on medication regimen complexity.AimInvestigate the impact of pharmacist‐led HMRs on simplifying medication regimen complexity using the Medication Regimen Complexity Index (MRCI).MethodA retrospective cohort study of 196 general practitioners (GPs) initiated HMRs, conducted over a period of 2 years (2020–2022) using two credentialed pharmacists in New South Wales, Australia. MRCI was used to measure the complexity at two separate time points, at baseline and following pharmacists' recommendations (assuming the GPs accepted all of the pharmacists' recommendations provided during the HMRs). The Wilcoxon signed‐rank test was used to determine the difference between the scores at baseline and after HMR. Ethical approval was granted by the University of Sydney Human Research Ethics Committee (Reference no: 2022/584) and the study conforms to the Australian National statement on the ethical conduct in human research.ResultsDuring the HMR service, pharmacists made a total of 792 recommendations (mean ± standard deviation [4.04 ± 2.3] per HMR), among which dosage and frequency adjustment, laboratory monitoring, and therapeutic monitoring were the most common, collectively accounting for almost half of the recommendations. The median MRCI score at baseline was 28.5 (interquartile range [IQR] 21.5–37.6) and following pharmacists' recommendations was 29 (IQR 21.9–37.1). The difference between the baseline and post‐HMR scores was not statistically significant.ConclusionOur study demonstrates the lack of significant reductions in medication complexity following HMRs as measured by the MRCI. However, these results need to be interpreted with caution as not all interactions with patients lead to a change in the MRCI score. Comprehensive examination of individual medication changes may provide more meaningful and clinically relevant inferences.