Associations of medication regimen complexity with medication adherence and clinical outcomes in patients with chronic obstructive pulmonary disease: a prospective study

Background: High medication burdens are common in patients with chronic obstructive pulmonary disease (COPD). This study aimed to explore the associations of medication regimen complexity index (MRCI) with medication adherence and clinical outcomes among patients with acute exacerbations of COPD (AECOPD) after hospital discharge. Methods: Data were obtained from a nationwide cohort study of inpatients with AECOPD in China. MRCI scores were calculated using the medication list 30 days after discharge and separated into COPD-specific and non-COPD MRCI scores. Medication adherence was measured by the withdrawal rate of COPD or inhaled long-acting bronchodilators 6 months after discharge. Clinical outcomes included re-exacerbations and COPD-related readmissions during the 30-day to 6-month follow-up period. The associations of MRCI with medication withdrawal and clinical outcomes were evaluated using univariate and multivariate logistic regressions. Potential covariates included sociodemographic factors, year of COPD diagnosis, post-bronchodilator percentage predicted forced expiratory volume in 1 s, mMRC score, CAT score, and comorbidities. Results: Among the 2853 patients included, the median total MRCI score was 7 [interquartile range (IQR), 7−13]. A high MRCI score (>7) was presented in 1316 patients (46.1%). Of the MRCI score, 91% were COPD specific. The withdrawal rates of the COPD and inhaled long-acting bronchodilators were 24.2% and 24.4%, respectively. Re-exacerbation and COPD-related readmission rates were 10.2% and 7.5%, respectively. After adjusting for covariates, patients with high total MRCI scores were less likely to discontinue COPD drugs [odds ratio (OR), 0.62; 95% confidence interval (CI), 0.52−0.74] and inhaled long-acting bronchodilators (OR, 0.68; 95%CI, 0.57−0.81); conversely, these patients were more likely to experience re-exacerbation (OR, 1.64; 95% CI, 1.27−2.11) and readmission (OR, 1.57; 95% CI, 1.17−2.10). Conclusion: MRCI scores were relatively low among post-hospitalized patients with AECOPD in China. Higher MRCI scores were positively associated with adherence to COPD or inhaled medications, and risk of re-exacerbation and readmission. Registration: ClinicalTrials.gov identifier: NCT02657525.