Socioeconomic inequalities in adherence to inhaled maintenance medications and clinical prognosis of COPD

Abstract Background Low socioeconomic status has been associated with adverse outcomes in chronic obstructive pulmonary disease (COPD), but population-based data are sparse. We examined the impact of education, employment, income, ethnicity, and cohabitation on the risk of suboptimal adherence to inhaled medication, exacerbations, acute admissions, and mortality among COPD patients. Methods Using nationwide healthcare registry data we identified 13,369 incident hospital clinic outpatients with COPD during 2008–2012. We estimated medication adherence as proportion of days covered (PDC) one year from first contact. With Poisson regression we computed adjusted relative risks (aRR) of poor adherence and non-use. With Cox regression we calculated adjusted hazard ratios (aHR) of clinical outcomes. Results 32% were poor adherers (PDC