NDT Advance Access published online on May 1, 2008
Nephrology Dialysis Transplantation, 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
Correspondence and offprint requests to: 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