title: Incidence and long-term outcome of severe asthma-COPD overlap compared to asthma and COPD alone: a 35-year prospective study of 57,053 middle-aged adults.
abstract: BACKGROUND
  Incidence and prognosis for severe asthma-COPD overlap is poorly characterized. We investigated incidence and long-term outcome for patients with asthma-COPD overlap compared to asthma and COPD alone.
  
  
  METHODS
  A total of 57,053 adults (aged 50-64 years) enrolled in the Danish Diet, Cancer, and Health cohort (1993-1997) were followed in the National Patients Registry for admissions for asthma (DJ45-46) and COPD (DJ40-44) and vital status. Asthma-COPD overlap was defined as at least one hospital admission for asthma and one for COPD (different time points), and incident asthma-COPD overlap as at least one of the diagnoses occurring after enrollment into the Diet, Cancer, and Health cohort.
  
  
  RESULTS
  A total of 1,845 (3.2%) and 4,037 (7.1%) participants had admissions for asthma and COPD, respectively, with 662 (1.2%) participants with asthma-COPD overlap. Incidence rate of asthma-COPD overlap per 1,000 person-years was higher in women (0.73) than in men (0.54) (P<0.02). Mortality rate was higher in asthma-COPD overlap (25.9 per 1,000 person-years) compared with COPD (23.1,P<0.05) and asthma (7.9,P<0.001) alone. Compared to COPD alone, mortality was higher in women with asthma-COPD overlap (19.6 and 25.5, respectively;P<0.01), and the excess mortality rate for asthma-COPD overlap patients was most prominent for younger age groups (12.9 compared to 7.2 and 4.6 for COPD and asthma alone, respectively;P<0.01).
  
  
  CONCLUSIONS
  This large population-based study revealed a higher incidence of severe asthma-COPD overlap in women compared to men, and furthermore that all-cause mortality is higher in women and younger subjects with asthma-COPD overlap compared with those with asthma or COPD alone.
authors.affiliation: Department of Pulmonary Medicine, Hvidovre Hospital, Hvidovre.
authors.forename: Camilla Boslev
authors.initials: CB
authors.lastname: Baarnes
authors.affiliation: Center for Epidemiology and Screening, Department of Public Health, University of Copenhagen.
authors.forename: Zorana Jovanovic
authors.initials: ZJ
authors.lastname: Andersen
authors.affiliation: Danish Cancer Society Research Center.
authors.forename: Anne
authors.initials: A
authors.lastname: Tjønneland
authors.affiliation: Department of Pulmonary Medicine, Hvidovre Hospital, Hvidovre; Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Charlotte Suppli
authors.initials: CS
authors.lastname: Ulrik
mesh_terms: D017677:Age Distribution; D000368:Aged; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D002423:Cause of Death; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D012042:Registries; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D013997:Time Factors
keywords: ACOS; COPD; asthma; asthma–COPD overlap; incidence; mortality; outcome