title: Interleukin-6 as a first-rated serum inflammatory marker to predict mortality and hospitalization in the oldest old: A regression and CART approach in the BELFRAIL study.
abstract: BACKGROUND
  Certain inflammatory biomarkers increase with age, provide information about general burden of illness and could cause or reflect any collateral damage to healthy cells and organs. However, comparative studies to predict adverse outcomes are missing. Therefore, our study validated and identified the principal prognostic marker to predict important adverse outcomes in the oldest old from an extensive battery of serum inflammatory markers.
  
  
  METHODS
  A large battery of potential 'inflammaging' markers (IL-1α, IL1-β, IL-4, IL-6, IL-8, IL-10, TNF-α, IFN-γ, EGF, VEGF, MCP-1, usCRP, prealbumin) was assessed in a representative sample of 415 heterogenic individuals 80years of age or older in the BELFRAIL study. Kaplan-Meier, Cox proportional hazards and CART analyses determined the overall prognostic value of these markers for predicting all-cause, cardiovascular and non-cardiovascular mortality as well as hospitalization.
  
  
  RESULTS
  Serum IL-6 and usCRP levels were strongly associated with time of survival, independent of cause of death. Serum IL-6 levels had the most robust dose-response relationship with mortality. To a lesser extent, IL-10 and IL-1β were associated with all-cause mortality but were restricted to non-cardiovascular or cardiovascular mortality, respectively. Having a low IL-6 at baseline (<1.77pg/ml) could predict 90% of those who were not at risk for all-cause mortality after 3years, even after adjusting for confounders. Similarly, we observed an 83.6% chance of identifying those cases with 0 or 1 hospitalization using low IL-6 serum levels.
  
  
  CONCLUSIONS
  The results suggest that a single measurement of low IL-6 serum levels is the first choice to guide clinical practice in the oldest old and could summarize the short-term risk of death and hospitalization.
authors.affiliation: Centre of General Practice, Department of Public Health and Primary Care, Katholieke Universiteit Leuven, Kapucijnenvoer 33, Blok J, 3000 Leuven, Belgium; Institute of Health and Society, Université Catholique de Louvain, Clos Chapelle-Aux-Champs 30, Bte 3005, 1200 Brussels, Belgium. Electronic address: wim.adriaensen@med.kuleuven.be.
authors.forename: Wim
authors.initials: W
authors.lastname: Adriaensen
authors.affiliation: Centre of General Practice, Department of Public Health and Primary Care, Katholieke Universiteit Leuven, Kapucijnenvoer 33, Blok J, 3000 Leuven, Belgium.
authors.forename: Catharina
authors.initials: C
authors.lastname: Matheï
authors.affiliation: Centre of General Practice, Department of Public Health and Primary Care, Katholieke Universiteit Leuven, Kapucijnenvoer 33, Blok J, 3000 Leuven, Belgium; Institute of Health and Society, Université Catholique de Louvain, Clos Chapelle-Aux-Champs 30, Bte 3005, 1200 Brussels, Belgium.
authors.forename: Bert
authors.initials: B
authors.lastname: Vaes
authors.affiliation: Centre of General Practice, Department of Public Health and Primary Care, Katholieke Universiteit Leuven, Kapucijnenvoer 33, Blok J, 3000 Leuven, Belgium.
authors.forename: Gijs
authors.initials: G
authors.lastname: van Pottelbergh
authors.affiliation: Laboratory of Analytical Biochemistry, Cliniques Universitaires St Luc, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Wallemacq
authors.affiliation: Centre of General Practice, Department of Public Health and Primary Care, Katholieke Universiteit Leuven, Kapucijnenvoer 33, Blok J, 3000 Leuven, Belgium; Institute of Health and Society, Université Catholique de Louvain, Clos Chapelle-Aux-Champs 30, Bte 3005, 1200 Brussels, Belgium.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Degryse
mesh_terms: D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D001530:Belgium / Q000453:epidemiology; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis*; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D015850:Interleukin-6 / Q000097:blood*; D053208:Kaplan-Meier Estimate; D008297:Male; D009026:Mortality; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D002097:C-Reactive Protein
keywords: Hospitalization; IL-6; Inflammaging; Mortality; Oldest old