Comparison of the use of potentially inappropriate medications and drug–drug interactions in patients aged over 65 with diagnoses of osteoarthritis and rheumatoid arthritis.

Abstract

Introduction: Recent studies show a high prevalence of polypharmacy in rheumatoid arthritis (RA), which may be associated with an increased risk of inappropriate prescribing and drug interactions, potentially compromising patient safety. Given the global aging of this population, it is crucial to assess the impact of polypharmacy in order to reduce risks and optimize medical care, as well as to compare it with another prevalent musculoskeletal disease such as osteoarthritis (OA).

Objectives: To determine the prevalence of polypharmacy and compare potentially inappropriate medications (PIMs) and drug interactions (DIs) in patients over 65 years of age with rheumatoid arthritis and osteoarthritis at the National Rehabilitation Institute.

Methodology: A retrospective, observational, and descriptive study was conducted in patients over 65 years old diagnosed with RA and OA, treated at INR LGII during 2024. Groups were matched by age and sex. To identify potentially inappropriate medications (PIMs) and drug interactions (DIs), the Beers Criteria and the mobile tool Drugs.com were used, respectively. Descriptive statistics were applied to estimate the prevalence of polypharmacy, PIMs, DIs, and adverse effects. Group comparisons were performed using Student’s t-test or Mann–Whitney U test, depending on data distribution, and Chi-square or Fisher’s exact test for categorical variables. Correlation between the number of prescribed medications and the presence of PIMs and DIs was assessed using Spearman's coefficient, considering statistical significance at p ≤ 0.05.

Results: A total of 59 patients per group were analyzed, all female, with similar average ages (71.4 and 72.2 years). Adverse events were more frequent in the RA group (47.45%) compared to OA (16.94%), with lymphopenia and anemia being most common in RA, and drowsiness/dizziness in OA. Polypharmacy was significantly more prevalent in RA patients (86.44% vs. 47.5%; p=0.001), as were DIs and medication-related adverse events (p=0.001 for both). A positive correlation was observed between the number of medications and the presence of PIMs and DIs in both groups (r > 3 and p < 0.01 in all cases). In the intra-group analysis of RA, there was no significant difference in the total number of drugs or in the use of DMARDs between those who presented adverse events and those who did not; however, the use of potentially inappropriate medications was higher among those with adverse events (p=0.03), especially in combinations involving methotrexate and leflunomide.

Conclusions: Patients with RA showed a higher frequency of polypharmacy and adverse events compared to those with OA. Although a positive correlation was identified between the total number of medications and the presence of PIMs and DIs, there were no differences in total drug use or DMARD use between those who experienced adverse events and those who did not. These findings suggest that adverse effects are more related to the quality rather than the quantity of medications, highlighting the importance of strengthening prescribing surveillance and optimizing therapeutic combinations in this population.