title: Trimestral variations of C-reactive protein, interleukin-6 and tumour necrosis factor-α are similarly associated with survival in haemodialysis patients.
abstract: BACKGROUND
  The impact of intra-individual changes of inflammatory markers [other than C-reactive protein (CRP)] on mortality in haemodialysis (HD) patients is unknown. We therefore studied survival in relation to trimestral variations of CRP, interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α).
  
  
  METHODS
  In 201 prevalent HD patients from the Mapping of Inflammatory Markers in Chronic Kidney Disease cohort, serum CRP, IL-6 and TNF-α were measured 3 months apart and survival was assessed during follow-up. Based on fluctuations along tertiles of distribution, four patterns were defined for each inflammatory marker: stable low, decrease, increase and stable high. Hazard ratios were calculated by the Cox proportional hazard model, and Pearson's test was used to correlate changes. CRP analyses were replicated in 472 incident HD patients from the Netherlands Cooperative Study on the Adequacy of Dialysis.
  
  
  RESULTS
  Patients with persistently elevated CRP values had the worst mortality in crude [HR 2.98 (95% CI 1.71-5.20)] and adjusted [2.79 (1.58-4.94)] Cox models, together with those who increased in their CRP levels [crude 3.27 (1.91-5.60); adjusted 3.13 (1.79-5.45)]. Similar survival patterns were observed for IL-6 and TNF-α variation categories. Correlations among these changes were, however, not strong. In the replication cohort, individuals with persistently elevated CRP values also showed the highest mortality risk [crude 3.38 (2.31-4.94); adjusted 2.33 (1.58-3.45)].
  
  
  CONCLUSIONS
  Trimestral variations of TNF-α, IL-6, and CRP are similarly associated with survival in HD patients. The agreement between changes of these biomarkers was low, suggesting that different pathways may trigger each of these markers.
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, The Netherlands.
authors.forename: Christiaan L
authors.initials: CL
authors.lastname: Meuwese
authors.forename: Sunna
authors.initials: S
authors.lastname: Snaedal
authors.forename: Nynke
authors.initials: N
authors.lastname: Halbesma
authors.forename: Peter
authors.initials: P
authors.lastname: Stenvinkel
authors.forename: Friedo W
authors.initials: FW
authors.lastname: Dekker
authors.forename: Abdul R
authors.initials: AR
authors.lastname: Qureshi
authors.forename: Peter
authors.initials: P
authors.lastname: Barany
authors.forename: Olof
authors.initials: O
authors.lastname: Heimburger
authors.forename: Bengt
authors.initials: B
authors.lastname: Lindholm
authors.forename: Raymond T
authors.initials: RT
authors.lastname: Krediet
authors.forename: Els W
authors.initials: EW
authors.lastname: Boeschoten
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Carrero
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D002097:C-Reactive Protein / Q000378:metabolism*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6 / Q000097:blood*; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000401:mortality* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D015996:Survival Rate; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein