In this cohort, it was found that hospitalization, multimorbidities, polypharmacy and diabetes mellitus increased the rate of PIM use over 10 years among the older adults in the community. The high usage of PIM in the cohort at the two moments analyzed can also be highlighted. The findings are relevant since they are in line with the World Health Agenda, in that since 2017 the reduction of potential risks related to the use of medicines has been listed as a priority by the World Health Organization .
The prevalence of PIM use in the two stages of this cohort was above 40%, a high result, however, consistent with estimates that used versions of the AGS Beers criteria prior to 2019 [5–10, 25]. Nevertheless, it is important to highlight that the inclusion of new drugs in the Beers 2019 list, and the form of classification of the PIM used in this study may have contributed to the high frequency observed . Various studies have been developed since the publication of the AGS Beers criteria 2019. In the United States, the prevalence of PIM prescription in a 5-year retrospective sample was 34.4% and there was a significant decrease in prevalence from 35.3% in 2011 to 32.5% in 2015 . Another study performed in the United States analyzing new PIM prescriptions showed that in a 90-day follow-up period, 2.5% received new PIM prescriptions . Roux et al. (2020) applied the Beers 2015 criteria in a 1-year follow-up study, and showed that 25.1% of the use of PIM initially prescribed at baseline persisted after one year .
Although the health conditions of older adults influence the increase in PIM consumption, specifically in Brazil, other factors such as the absence of a surveillance system and information on the use of PIM in older adults, communication failures between different prescribers, the lack of training for people on the subject of aging with a focus on pharmacovigilance contribute to persistent PIM use. Consequently, it is important that measures for deprescribing are implemented in order to confront this problem. Deprescribing refers to the review and evaluation of the long-term therapeutic plan, which allows suspending, replacing or modifying the dose of drugs that were properly prescribed, however, which, given certain clinical conditions, may be considered to have an unfavorable risk-benefit ratio . Therefore, in the context of the aging process and use of medications, deprescribing is related to polypharmacy and PIM, and its applicability is favorable for pharmacological treatment in older adults. Some initiatives, such as the International Group for Reducing Inappropriate Medication Use & Polypharmacy (IGRIMUP), which brings together 26 countries, propose recommendations to reduce PIM use among older adults , however, in Brazil, the recommendations for deprescribing are still incipient.
It is known that multimorbidities are risk factors for polypharmacy  which could explain the increase in the rate of PIM use throughout the follow-up in this study. National [6, 29–31] and international [32–35] studies have shown that a higher number of diseases was associated with PIM use. The use of PIM results from a cascade of events: changes in health conditions, need for treatment and disease control, access to professionals from different specialties, and the use of many medications. In general, the treatment for most geriatric diseases is with the use of drugs, which are not always the most appropriate due to their potential to cause harm to the patient. For each new drug introduced into adult therapy, there is a corresponding increased risk of up to 10% for an adverse event . The World Health Organization has included polypharmacy as one of the three priority categories of the 3rd Global Patient Safety Challenge , which requires attention in populations similar to the one in this study with a high prevalence of polymedication and PIM use.
Being diagnosed with Diabetes Mellitus (DM) increased the rate of PIM use in the cohort period. Some studies have shown that older adults with DM consume multiple medications in greater proportions [37–42], which in consequence may increase the risk of using some type of PIM. A recent study in Quebec showed that more than half of the people with DM used at least one PIM in a year . Furthermore, people with DM have more comorbidities than the general population. In Brazil, a representative study with 70 municipalities showed that although DM was not the disease in the highest proportion, it was the one with the highest number of associated comorbidities . Added to this, the symptoms or systemic manifestations of the different types of complications can lead to the use of health services and the consequent prescribing of other medications, which may include PIM. Considering the growing number of people with DM and the proportion that use PIM, the impacts on people's health and in terms of public health are significant .
Over the 10 years, there was an increase in the rate of PIM use in the older adults who were hospitalized. Hospitalization was a risk factor reported for PIM use in previous studies [45–47]. Hospitalized older adults are more frequently submitted to drug therapy, due to their preexisting clinical conditions and those acquired during the hospitalization process . Therefore, changes in prescriptions can increase the risk of using a PIM. A study carried out in the city of São Paulo showed that PIM use increased the frequency of unscheduled hospitalization in older adults by 64% . Considering this, it is relevant to highlight the importance of specific care for the older adult population during hospitalization that considers their needs, and functionality, in addition to an appropriate therapeutic regimen. The use of PIM can either be a risk factor for hospitalization or a consequence of it, however, the presence of professionals with specific training and education can prove effective in preventing unnecessary PIM use. Increased awareness and specific training is necessary for the multidisciplinary team regarding the risks of using PIM in this population that is highly susceptible to harm, this action is in accordance with the global health agenda .
Despite the potential, in this study it was not possible to identify the interruption of PIM use over the period of 10 years, or to verify at what moment other PIM were included in the treatment of the participants, thereby constituting a limitation of the study. Nevertheless, this study is a population cohort of older adults from a capital city of the Central-West region of Brazil, which used the updated Beers criterion, allowing for more accurate estimates of PIM use.
The use of PIM was high at the two moments analyzed, reaching more than 50% of the participants. Risk factors for PIM use among older adults in the community were related to their health conditions, such as the presence of three or more diseases, polypharmacy, diabetes and hospitalization. Interventions are needed to improve the process of drug prescriptions in order to prevent unnecessary and inappropriate medications for older adults from being continuously prescribed. Future studies are needed to implement actions to reduce inappropriate prescriptions.