Potentially Inappropriate Medication Use and the Hospitalization Rate among Thai Elderly Patients: a Retrospective Cohort Study

Background: Older adults are at risk of receiving potentially inappropriate medications (PIMs) because their incidence of medical conditions and diseases is higher than younger individuals. This situation is of particular concern because the biological and physiologic changes in older adults make them vulnerable to PIMs. Thailand has become an aging society since the year 2002, so it is essential to evaluate the effect of PIMs in this age group. Objectives: This study examined the association between PIM use and the hospitalization rate in Thai older patients, in addition to identifying the factors associated with the hospitalization rate. Methods: In this retrospective cohort study, the electronic medical data of patients aged 60 years and older who visited the outpatient department (OPD) in 2015 were collected. The patients were categorized into PIM and non-PIM users according to the Beers 2019 criteria. An association between PIM use and the hospitalization rate was examined. Data were analyzed through descriptive and analytic statistics to examine the association between PIM use and the hospitalization rate via relative risk. Log-binomial regression was conducted to explore factors that impacted the hospitalization rate. Results: A total of 32,261 patients were collected, with the majority being female (59.65%) and the mean age of 70.21 ± 7.88 years. Overall, 63.98% of the patients (20,641 patients) were PIM users and 49.45% (15,952 patients) received polypharmacy (≥5 medications). The most common PIM prescription was Proton-pump inhibitors, making 27.51% of all medications prescribed. The results showed that PIM use increased the risk of hospitalization by 1.31 times (adjusted RR 1.31 95% CI 1.21-1.41, p-values < 0.001). Other factors affecting the rate of hospitalizations included age, gender, polypharmacy, and the number of OPD visits. Conclusions PIMs were commonly prescribed to older patients in the OPD and were significantly associated with subsequent hospitalization. A provision of an alternative drug list can help physicians avoid prescribing PIMs to older patients. If PIMs prescription is unavoidable, physicians should closely monitor drug-related problems and deprescribe when PIMs are not indicated.