title: Unexplained week-to-week variation in BNP and NT-proBNP is low in chronic heart failure patients during steady state.
abstract: BACKGROUND
  The usefulness of brain-natriuretic-peptide (BNP) and N-terminal-pro-brain-natriuretic-peptide (NT-proBNP) for monitoring of chronic heart failure (CHF) patients has been questioned because of high levels of unexplained variation.
  
  
  OBJECTIVE
  Week-to-week total variance (CV(T)), unexplained variation (CV(I)), reference change values (RCV), index of individualities (IOI) and number of samples (N) with week-to-week intervals needed to estimate the underlying homeostatic set point (+/-15%) for BNP and NT-proBNP were calculated in pre-specified stable CHF patients.
  
  
  RESULTS
  We measured plasma concentrations of BNP and NT-proBNP, clinical and laboratory variables in 20 CHF patients with a 7-days interval. Only patients considered to be in steady state were included. The CV(I) was 15% (BNP) and 8% (NT-proBNP). CV(T) was 16% (BNP) and 8% (NT-proBNP) and RCV was 43% (BNP) and 23% (NT-proBNP). IOI was 0.14 for BNP and 0.03 for NT-proBNP and N was 1 for BNP and 1 for NT-proBNP.
  
  
  CONCLUSIONS
  Our data demonstrate that unexplained variation of BNP and NT-proBNP is low in CHF patients during steady state, which is a prerequisite for the use of these peptides for monitoring of the disease.
authors.affiliation: Department of Cardiology and Endocrinology, Clinic E, Frederiksberg University Hospital, Ndr. Fasanvej 57-59, DK-2000-Frederiksberg, Denmark. morten.schou@fh.hosp.dk
authors.forename: Morten
authors.initials: M
authors.lastname: Schou
authors.forename: Finn
authors.initials: F
authors.lastname: Gustafsson
authors.forename: Per H
authors.initials: PH
authors.lastname: Nielsen
authors.forename: Lene H
authors.initials: LH
authors.lastname: Madsen
authors.forename: Andreas
authors.initials: A
authors.lastname: Kjaer
authors.forename: Per R
authors.initials: PR
authors.lastname: Hildebrandt
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D018579:Patient Selection; D010446:Peptide Fragments / Q000097:blood*; D012016:Reference Values; D015203:Reproducibility of Results; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D016277:Ventricular Function, Left / Q000502:physiology
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain