title: Coronary artery calcification scores in patients with chronic kidney disease prior to dialysis: reliability as a trial outcome measure.
abstract: BACKGROUND
  Coronary artery calcification (CAC) is prevalent in patients with chronic kidney disease (CKD). Data on the reliability and validity of high-resolution computerized tomography (HRCT) in patients with CKD is lacking. The purpose of this study was to evaluate the inter- and intra-reviewer agreement and inter-scan reproducibility of CACS measurement with HRCT in a cohort of patients with CKD prior to dialysis, and to compare the change in CACS at 30 minutes to the change in CACS over 1 year.
  
  
  METHODS
  Thirty-three patients with CKD not yet on dialysis underwent an HRCT scan at baseline and 1 year to assess for CAC and CAC progression. Two radiologists independently reviewed films and each radiologist re-reviewed a randomly selected subset of films they had previously viewed, to assess for inter-reviewer and intra-reviewer reliability, respectively. Patients underwent a repeat scan within 30 min of the first baseline scan to assess for inter-scan reproducibility.
  
  
  RESULTS
  At baseline, eight patients (24%) had no CAC. Of the 25 patients (76%) with CAC, 10 (40%) had severe calcification. Intra-reviewer agreement was 83%. Inter-reviewer agreement ranged between 77 and 94%. Six (27%) of the patients with >30 baseline CACS had >15% change in CACS following repositioning. Four of these patients had an increase in CACS with position change [18% (95% CI: 5-40%)]. Of the 21 patients who underwent a follow-up scan at 1 year, 7 (33%) demonstrated CACS progression.
  
  
  CONCLUSIONS
  There is significant imprecision in HRCT-derived CACS in CKD patients. This suggests a need for standardization of methods of CACS measurement with HRCT.
authors.affiliation: Division of Nephrology, University of British Columbia, Vancouver, British Columbia, Canada. arbieb@hotmail.com
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Barraclough
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Stevens
authors.forename: Lee
authors.initials: L
authors.lastname: Er
authors.forename: Debbie
authors.initials: D
authors.lastname: Rosenbaum
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Brown
authors.forename: Pari
authors.initials: P
authors.lastname: Tiwari
authors.forename: Adeera
authors.initials: A
authors.lastname: Levin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000150:complications* / Q000000981:diagnostic imaging; D015331:Cohort Studies; D003327:Coronary Disease / Q000150:complications* / Q000000981:diagnostic imaging; D003331:Coronary Vessels / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D017063:Outcome Assessment, Health Care; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000150:complications* / Q000628:therapy; D015203:Reproducibility of Results; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000706:statistics & numerical data