The patterns and implications of potentially suboptimal medicine regimens among older adults: a narrative review

In the context of an ageing population, the burden of disease and medicine use is also expected to increase. As such, medicine safety and preventing avoidable medicine-related harm are major public health concerns, requiring further research. Potentially suboptimal medicine regimens is an umbrella term that captures a range of indicators that may increase the risk of medicine-related harm, including polypharmacy, underprescribing and high-risk prescribing, such as prescribing potentially inappropriate medicines. This narrative review aims to provide a background and broad overview of the patterns and implications of potentially suboptimal medicine regimens among older adults. Original research published between 1990 and 2021 was searched for in MEDLINE, using key search terms including polypharmacy, inappropriate prescribing, potentially inappropriate medication lists, medication errors, drug interactions and drug prescriptions, along with manual checking of reference lists. The review summarizes the prevalence, risk factors and clinical outcomes of polypharmacy, underprescribing and potentially inappropriate medicines. A synthesis of the evidence regarding the longitudinal patterns of polypharmacy is also provided. With an overview of the existing literature, we highlight a number of key gaps in the literature. Directions for future research may include a longitudinal investigation into the risk factors and outcomes of extended polypharmacy, research focusing on the patterns and implications of underprescribing and studies that evaluate the applicability of tools measuring potentially inappropriate medicines to study settings. PLAIN LANGUAGE SUMMARY: A review on potentially inappropriate medicine regimens Medicine use in older age is common. Older adults with more than one chronic condition are likely to use multiple medicines to manage their health. However, there are times when taking multiple medicines may be unsafe and the number of medicines, or the combination of medicines used, may increase the risk of poor health outcomes. The term medicine regimens is used to describe all the medicines an individual takes. There are several ways to measure when a medicine regimen may be inappropriate and, therefore, potentially harmful. Much research has been published looking into potentially inappropriate medicine regimens. To bring together the current research, this review provides a background on the different measures of potentially inappropriate medicine regimens. It also summarizes how many people may experience potentially inappropriate medicine regimens, the impact it is having on their health and who may be at greater risk. In doing so, we found a number of gaps in the existing evidence, indicating that our understanding of potentially inappropriate medicine regimens is incomplete. This review highlights gaps in knowledge that can be addressed by future research. With an improved understanding of potentially inappropriate medicine regimens, we may be able to better identify those at greater risk to prevent or minimize the impact of poorer health outcomes related to unsafe medicine use.