NDT Advance Access published online on September 19, 2007
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfm590
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CKD stage-to-stage progression in native and transplant kidney disease*
1Department of Medicine, Nephrology Section, University of Minnesota and 2University of Wisconsin, School of Medicine and Public Health, Madison, WI, USA
Correspondence and offprint requests to: Arjang Djamali, MD, Assistant Professor of Medicine, Department of Medicine, Nephrology Section, University of Wisconsin School of Medicine and Public Health, 3034 Fish Hatchery Road, Ste B, Madison, WI, 53713, USA. Email: axd{at}medicine.wisc.edu
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Abstract |
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Background. Kidney half-life and inter-stage progression rates in native chronic kidney disease (CKD) and CKD-transplant (CKD-T) remain unknown.
Methods. We examined stage-to-stage progression/regression rates in patients with CKD (n = 601) and CKD-T (n = 431) between 1991 and 2001. Kidney function was estimated by Cockcroft–Gault and MDRD eGFR formulae. Kaplan–Meier analyses determined progression and regression half-lives, defined as the time required for 50% of kidneys to advance towards a higher or lower stage of CKD, respectively.
Results. Most (67%) of the patients were in stage 3. Patients with native CKD were more likely to progress compared to CKD-T (inter-stage progression rates 12 vs 4 cases per 100 patient-years, P < 0.0001). Accordingly, estimated glomerular filtration rate (eGFR)-based progression half-lives were significantly shorter in CKD compared to CKD-T [6 vs 9.6 years, P < 0.0001, hazard ratio (HR) 3.1, 95% confidence interval (CI) = 2.5–3.7]. Creatinine clearance (CCR)-based stage half-lives were 7.2 months shorter in each group (5.4 and 9 years in CKD and CKD-T, respectively). Despite slower progression rates in patients with transplant kidney disease, adjusted patient survival rates were significantly decreased in CKD-T compared to CKD. Only Scr and CCR-based formulae were significantly associated with patient and allograft outcomes in the CKD-T group. Moreover, death rates were not different in stage 3 compared to stage 2 CKD-T, suggesting that eGFR and the current staging classification have a limited value to predict patient death in this cohort.
Conclusion. Kidney half-lives per stage of CKD may be a novel tool to examine disease progression.
Keywords: CKD; CKD-T; half-life; kidney transplantation; outcomes; progression
*Parts of this work were presented in an abstract form at the American Society of Nephrology Annual Meeting 2006, San Diego, USA in Journal of American Society of Nephrology October 2006. F-FC-157.
Received for publication: 24. 3.07
Accepted in revised form: 2. 8.07