Urban-rural disparities in pneumonia in chronic obstructive pulmonary disease in Denmark: a nationwide register-based cross-sectional study

<bold>Background:</bold> Urban-rural disparities in pneumonia in patients with chronic obstructive pulmonary disease (COPD) have been documented in USA, but have not been investigated in a European context. <bold>Aims and objectives:</bold> To investigate urban-rural disparities in pneumonia incidence in patients with COPD in Denmark. <bold>Methods:</bold> A nationwide register-based cross-sectional study. All patients in Denmark with a J44 ICD-10 diagnosis code of COPD alive on the 31st of December 2018 were included (99,057 patients). Patients were grouped according to municipality type residence on an urban-rural spectrum (capital, metropolitan, provincial, commuter, rural). The number of moderate (redeemed prescriptions of antibiotics typically used for pneumonia) and severe (hospitalization for pneumonia) pneumonias during 2018 were collected. The risk of both moderate and severe pneumonia was assessed with Poisson regressions with capital municipality as reference and adjusting for age, sex, educational level, co-habitation status, and inhaled corticosteroid treatment dose. <bold>Results:</bold> Compared to capital municipalities, living in other municipality types was significantly associated with an increased risk of moderate pneumonia (incidence rate ratios (IRR) from 1.22 to 1.33) and a decreased risk of pneumonia hospitalization (IRRs from 0.81 to 0.90). <bold>Conclusions:</bold> Urban-rural disparities in pneumonia in COPD exist in Denmark, with patients in capital municipalities having a decreased risk of moderate pneumonia but an increased risk of hospitalization for pneumonia. This is the first study to confirm that such disparities exist in Europe.