The association between polypharmacy and medication regimen complexity and antibiotic use in bronchiectasis

Background Polypharmacy is associated with an increased risk of adverse drug events, inappropriate prescribing and medication errors. People with bronchiectasis have frequent pulmonary exacerbations that require antibiotic therapy. Objective This study aimed to measure polypharmacy and medication regimen complexity in bronchiectasis patients and to explore associations between these factors and oral and intravenous (IV) antibiotic use for suspected pulmonary exacerbations. Setting Patients were sampled from the Regional Bronchiectasis Clinic at the Belfast Health and Social Care Trust, Northern Ireland. Method Data on medicines were collected from patients' records and used to measure polypharmacy using three thresholds (≥ 4, ≥ 10, and ≥ 15 medicines'). Medication regimen complexity was calculated using the medication regimen complexity index (MRCI). Data analysis investigated differences in outcomes across polypharmacy thresholds and correlations with MRCI. Main outcome measure Primary outcomes were prescriptions for oral antibiotics and IV antibiotics, in the past 6 months and 2 years, respectively. Results Over three-quarters of the sample (N = 95) were prescribed ≥ 4 medicines (n = 74; 77.9%), 31 patients were prescribed ≥ 10 medicines (33.0%), and 12 patients (12.8%) were prescribed ≥ 15 medicines. The median MRCI was 26. Patients prescribed ≥ 10 medicines were over three times more likely to have had an IV antibiotic in the past 2 years (adjusted odd ratio 3.44, 95% confidence intervals 1.15-10.31). Conclusion There were significant differences in all outcomes across the '≥ 10 medicines' threshold. MRCI was positively correlated with oral and IV antibiotic usage. These findings also suggest a possible link between polypharmacy and medicines regimen complexity, and poorer outcomes.