Comorbidities and mortality among patients with chronic obstructive pulmonary disease

INTRODUCTION: Comorbidities are common in patients with chronic obstructive pulmonary disease (COPD). Estimates of prevalence, incidence and prognostic impact of comorbidities provide foundational knowledge of COPD epidemiology. We examined the prevalence, incidence and prognostic impact of 21 comorbidities among patients with COPD compared with the Danish general population. METHODS: We conducted a nationwide, population-based cohort study based on longitudinal Danish registry data, covering all Danish hospitals (2010-2021). The cohorts comprised 142 973 patients with a first-time hospital-based diagnosis of COPD and 428 917 age-matched and sex-matched comparators from the general population. During follow-up, we estimated the 5-year risk and risk difference, using competing risk methods when applicable. RESULTS: At time of diagnosis, the comorbidities with the highest prevalence were mood, stress-related or anxiety disorders (25.2% for patients with COPD vs 13.1% for comparators), osteoporosis/hip fractures (17.4% vs 9.9%), diabetes (15.6% vs 10.5%), peripheral arterial disease (13.5% vs 4.9%) and heart failure (13.3% vs 4.0%). During follow-up, the risk of most incident comorbidities was markedly elevated among patients with COPD. The five comorbidities associated with the highest 5-year absolute risk difference with respect to the risk in the general population were mood, stress-related or anxiety disorders (5.7%), osteoporosis/hip fractures (5.6%), heart failure (4.2%), smoking-related cancers (2.8%) and peripheral arterial disease (2.7%). The 5-year mortality risk was 43% vs 17.7%. Among patients with COPD, the 5-year mortality risk markedly increased with the number of comorbidities present. CONCLUSIONS: Our population-based findings underscore the importance of considering comorbidities in the management of COPD.