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<0.8) and 5% non-users (PDC = 0). Analyses showed a higher risk of poor adherence among unemployed (aRR1.36, 95% CI 1.20–1.54), low income patients (aRR = 1.07, 95% CI 1.00–1.16), immigrants (aRR = 1.29, 95% CI 1.17–1.44), and patients living alone (aRR = 1.17, 95% CI 1.11–1.24). Similarly, non-use was associated with unemployment (aRR = 2.75, 95% CI 2.09–3.62), low income (aRR = 1.37, 95% CI 1.10–1.70), immigrant status (aRR = 1.56, 95% CI 1.17–2.08), and living alone (aRR = 1.53, 95% CI 1.30–1.81). Low education was associated with exacerbations (aHR = 1.21, 95% CI 1.10–1.35) and admissions (aHR = 1.22, 95% CI 1.07–1.38). Low income was associated with admissions (aHR = 1.20, 95% CI 1.09–1.32), and death (aHR = 1.11, 95% CI 0.99–1.25). The unemployed and those living alone had lower exacerbation-risk but higher mortality-risk. Conclusions In Denmark, health equity is a stated priority in a public health care system. Nevertheless, there are substantial socioeconomic inequalities in COPD treatment and outcomes. © 2016 Elsevier Ltd

Medicine Compliance Registries SES ICS LAMA Admissions LABA Proportion of days covered (PDC) Exacerbations

hospital admission unemployment prospective study educational status immigrant clinical outcome hospitalization beta 2 adrenergic receptor stimulating agent Registries lowest income group muscarinic receptor blocking agent register Prospective Studies human long acting drug corticosteroid middle aged Adrenergic beta-2 Receptor Agonists Adrenal Cortex Hormones Denmark statistics and numerical data cholinergic receptor blocking agent Muscarinic Antagonists priority journal corticosteroid therapy Aged Administration, Inhalation outpatient cohabitation medication compliance prognosis maintenance therapy chronic obstructive lung disease inhalational drug administration social status Hospital Mortality Humans male female Socioeconomic Factors risk factor Risk Factors socioeconomics Outcome Assessment (Health Care) combination drug therapy Drug Therapy, Combination Pulmonary Disease, Chronic Obstructive Article patient compliance major clinical study adult disease exacerbation outcome assessment Disease Progression ethnicity mortality Medication Adherence