Urban-rural and socio-economic differences in inhaled corticosteroid treatment for chronic obstructive pulmonary disease: A nationwide register-based cross-sectional study

Background: Urban-rural disparities within chronic obstructive pulmonary disease (COPD) have been documented in USA, but not in Europe. Inhaled corticosteroids (ICS) are widely used in COPD despite strict recommendations. We aimed to investigate urban-rural and socioeconomic differences in ICS treatment for COPD. Methods: A Danish nationwide register-based cross-sectional study. All patients alive on the December 31, 2018 with a J44 ICD-10 diagnosis code (COPD) were included (99,057 patients). Daily average ICS dose was calculated from the accumulated ICS use during 2018 based on redeemed prescriptions. Patients were divided into groups: No ICS, low dose ICS, medium dose ICS, high dose ICS. A multinomial logistic regression model including educational level, co-habitation status, age, and sex was performed with “No ICS” as reference group. Results: Compared to capital municipalities, living in other municipality types was associated with an increased probability of receiving medium and high dose ICS treatment, and increasing odds ratios (ORs) were seen with increasing ICS dose (medium dose ICS: ORs between 1.31 (95 % confidence interval (CI) 1.24–1.38) and 1.35 (95%CI 1.28–1.41), high dose ICS: ORs between 1.73 (95%CI 1.59–1.88) and 1.80 (95%CI 1.68–1.92)). Patients had increased probability of receiving ICS treatment if they were female, were co-habiting, or had completed only primary education. Conclusion: Patients with a hospital-registered COPD diagnosis in non-capital municipalities receive more ICS, and in higher doses, compared to patients in capital municipalities. This is the first study to confirm that such urban-rural differences exist in Europe, and further research on this area is warranted.