title: The impact of co-morbidity burden on appropriate implantable cardioverter defibrillator therapy and all-cause mortality: insight from Danish nationwide clinical registers.
abstract: In a nationwide cohort of primary (PP-ICD) and secondary prevention (SP-ICD) implantable cardioverter defibrillator (ICD) patients, we aimed to investigate the association between co-morbidity burden and risk of appropriate ICD therapy and mortality.
  
  
  
  We identified all patients >18 years, implanted with first-time PP-ICD (n = 1873) or SP-ICD (n = 2461) in Denmark from 2007 to 2012. Co-morbidity was identified in administrative registers of hospitalization and drug prescription from pharmacies. Co-morbidity burden was defined as the number of pre-existing non-ICD indication-related co-morbidities including atrial fibrillation, diabetes, chronic obstructive pulmonary disease, chronic renal disease, liver disease, cancer, chronic psychiatric disease, and peripheral and/or cerebrovascular disease, and divided into four groups (co-morbidity burden 0, 1, 2, and ≥3). Through Cox models, we assessed the impact of co-morbidity burden on appropriate ICD therapy and mortality. Increasing co-morbidity burden was not associated with increased risk of appropriate therapy, irrespective of implant indication [all hazard ratios (HRs) 1.0-1.4, P = NS]. Using no co-morbidities as reference, increasing co-morbidity burden was associated with increased mortality risk in PP-ICD patients (co-morbidity burden 1, HR 2.1; comorbidity burden 2, HR 3.7; co-morbidity burden ≥3, HR 6.6) (all P < 0.001) and SP-ICD patients (co-morbidity burden 1, HR 2.2; co-morbidity burden 2, HR 3.8; co-morbidity burden ≥3, HR 5.8). With increasing co-morbidity burden, an increasing frequency of patients died without having utilized their device, with 72% PP-ICD and 45% SP-ICD patients with co-morbidity burden ≥3 dying without prior appropriate ICD therapy.
  
  
  
  Increasing co-morbidity burden was not associated with increased risk of appropriate ICD therapy. With increasing co-morbidity burden, mortality increased, and a higher proportion of patients died, without ever having utilized their device.
authors.affiliation: Department of Cardiology, Herlev-Gentofte University Hospitals, Copenhagen, Denmark.
authors.forename: Anne Christine
authors.initials: AC
authors.lastname: Ruwald
authors.affiliation: Department of Cardiology, Herlev-Gentofte University Hospitals, Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Vinther
authors.affiliation: Department of Cardiology, Herlev-Gentofte University Hospitals, Copenhagen, Denmark.|National Institute of Public Health, Copenhagen, Denmark.|Department of Cardiology, University of Southern Denmark, Odense, Denmark.|The Danish Heart Foundation.
authors.forename: Gunnar H
authors.initials: GH
authors.lastname: Gislason
authors.affiliation: Department of Cardiology, Odense University Hospital, Odense, Denmark.
authors.forename: Jens Brock
authors.initials: JB
authors.lastname: Johansen
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jens Cosedis
authors.initials: JC
authors.lastname: Nielsen
authors.affiliation: Department of Cardiology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Helen Høgh
authors.initials: HH
authors.lastname: Petersen
authors.affiliation: Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Sam
authors.initials: S
authors.lastname: Riahi
authors.affiliation: Department of Cardiology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology; D002561:Cerebrovascular Disorders / Q000453:epidemiology; D015331:Cohort Studies; D015897:Comorbidity; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D003718:Denmark / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000453:epidemiology; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology; D016491:Peripheral Vascular Diseases / Q000453:epidemiology; D011322:Primary Prevention; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012042:Registries; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology; D012189:Retrospective Studies; D055502:Secondary Prevention
keywords: Appropriate ICD therapy; Co-morbidity burden; Implantable cardioverter defibrillators; Implantation rate; Mortality