Prevalence of polypharmacy and drug interaction in older adults with rheumatic disease

Older people with rheumatic diseases tend to have a greater number of associated comorbidities, which will require the use of more drugs, increasing the risk of hospitalizations, complications, and drug interactions. In Mexico, there has been an estimated prevalence of polypharmacy of up to 55%, however there are scarce reports on the topic in our elderly population with rheumatic diseases. We aimed to determine the prevalence of polypharmacy and the association of drug interactions in patients treated for rheumatic disease.

A retrospective observational study was conducted on patients undergoing treatment for rheumatic diseases who were treated in geriatrics and rheumatology clinics from January to December 2021. The presence of polypharmacy and drug interactions was evaluated using the BOT Plus Pharmacological Surveillance System. The prevalence of polypharmacy and the association of drug interactions were estimated.

We evaluated 320 patients, with a mean age of 67.05±5.8 years, predominantly female (85%). The prevalence of polypharmacy was 68.1% (n=218), of which 214 (98.1%) patients had related drug interactions; 27.1% were severe and 53.2% as moderate interactions. Factors related with increased risk of drug interactions were being exposed to hypertension increased the risk of drug interactions (POR 1.75, 95% CI 1.44-2.14; P<0.001), having osteoarthritis (POR 1.21, 95% CI 1.04-1.42; P=0.032) and thyroid disease (POR 1.45, 95% CI 1.28-1.65; P=0.001). The most prevalent serious interactions were leflunomide-methotrexate in 27 (46.5%) patients and buprenorphine-tramadol in 8 (13.7%).

A high prevalence of polypharmacy and drug interactions was observed in elderly patients with rheumatic diseases. The main associated factors were comorbidities, particularly high blood pressure, osteoarthritis and thyroid diseases.