NDT Advance Access originally published online on May 1, 2008
Nephrology Dialysis Transplantation 2008 23(10):3199-3205; doi:10.1093/ndt/gfn234
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Coronary artery calcification scores in patients with chronic kidney disease prior to dialysis: reliability as a trial outcome measure
1 Division of Nephrology, University of British Columbia, Vancouver, British Columbia, Canada 2 Division of Nephrology, Tufts-New England Medical Center, Boston, MA, USA 3 Department of Radiology, St Paul's Hospital, Vancouver, British Columbia, Canada
Katherine Barraclough, Department of Nephrology, St. Paul's Hospital, 1081 Burrard Street, Providence Building, 6th Floor, Room 6010A, Vancouver V6Z 1Y6, Canada. Tel: +1-604-8754111; Fax: +1-604-8068120; E-mail: arbieb{at}hotmail.com
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Abstract |
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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.
Keywords: cardiovascular disease; chronic kidney disease; coronary artery calcification; high-resolution computerized tomography; test reliability
Received for publication: 23.12.07
Accepted in revised form: 4. 4.08