title: The joint subclinical elevation of CRP and IL-6 is associated with lower health-related quality of life in comparison with no elevation or elevation of only one of the biomarkers.
abstract: BACKGROUND
  Measures of health-related quality of life (HRQoL), like the Short Form (SF)-36, have been suggested to correlate with inflammatory biomarkers. It is, however, unclear whether a joint measure of two inflammatory biomarkers would bring additional information in comparison with evaluation of one inflammatory biomarker.
  
  
  OBJECTIVE
  To evaluate associations between SF-36 and low-grade inflammation in a Swedish population, with emphasis on a combined measure of C-reactive protein (CRP) and interleukin-6 (IL-6) as a proxy for low-grade inflammation.
  
  
  METHODS
  In a randomly selected sample of a middle-aged Swedish general population (n = 905; aged 45-69 years, 50% women), relations between SF-36 parameters and the biomarkers were tested. Regression and correlation analyses were adjusted for sex, age, presence of disease, lifestyle, and psychological factors.
  
  
  RESULTS
  After adjustment for sex and age, HRQoL was significantly lower in the group with a joint elevation of CRP and IL-6 in comparison with either the group with no elevation or the groups showing elevation of one of the two biomarkers. Also after full adjustments, the combined measure of elevated CRP and IL-6, with few exceptions, was associated with significantly lower HRQoL in comparison with elevations in one of them, difference ranging from 4 (Mental Health scale) to 18 scale steps (Role-Physical scale).
  
  
  CONCLUSIONS
  This study confirms that there is a relationship between HRQoL and low-grade inflammation. In particular, SF-36 scores are significantly lower in a group with joint elevation of IL-6 and CRP, in comparison with elevation of either one of them.
authors.affiliation: Unit of Research and Development in Local Health Care (FoU-enheten för Närsjukvården i Östegötland), County of Östergötland, 581 85, Linköping, Sweden. peter.garvin@regionostergotland.se.|Division of Community Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden. peter.garvin@regionostergotland.se.
authors.forename: Peter
authors.initials: P
authors.lastname: Garvin
authors.affiliation: Unit of Research and Development in Local Health Care (FoU-enheten för Närsjukvården i Östegötland), County of Östergötland, 581 85, Linköping, Sweden.|Division of Community Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Evalill
authors.initials: E
authors.lastname: Nilsson
authors.affiliation: Division of Neuro and Inflammatory Sciences, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Ernerudh
authors.affiliation: Division of Community Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Margareta
authors.initials: M
authors.lastname: Kristenson
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D006304:Health Status; D006801:Humans; D007249:Inflammation / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D008019:Life Style; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D011788:Quality of Life / Q000523:psychology*; D011795:Surveys and Questionnaires; D044465:White People
chemical_list: D015415:Biomarkers; C508600:IL6 protein, human; D015850:Interleukin-6; D002097:C-Reactive Protein
keywords: Biomarkers; CRP; Health-related quality of life; Inflammation; Interleukin; Population; SF-36