Prevalence and staging of chronic kidney disease in renal transplant recipients.

INTRODUCTION: Diagnosis and staging of chronic kidney disease (CKD) is important for management and prevention of renal disease progression. It is unclear whether K/DOQI guidelines of the National Kidney Foundation are applicable to diagnosis of CKD in renal transplant recipients (RTRs) and which method is most appropriate for estimating glomerular filtration.

OBJECTIVES: To determine the prevalence and staging of CKD in RTRs, according to K/DOQI guidelines, and the prevalence of complications of CKD.

SUBJECTS AND METHODS: This cross-sectional study included RTRs at least six months post-transplantation followed at a single out-patient service. The glomerular filtration rate (GFR) was estimated with two different equations: the MDRD equation (Modification of Diet in Renal Disease) with four variables (age, creatinine level, gender, and race) and the Cockcroft-Gault (CG) formula. Patients with GFR more than 60 mL/min/1.73 m2 were diagnosed with CKD only in the presence of renal damage (hematuria, proteinuria, or evidence of injury in renal biopsy). CKD staging was compared to the two equations and the prevalence of complications was determined.

RESULTS: The study evaluated 241 RTRs (average age: 40.6 +/- 12.5 yr, 62.2% male; 4.5% black, 50.6% from cadaveric donors). Average follow-up time was 6.8 +/- 6.1 yr and the average baseline creatinine level was 1.48 +/- 0.72 mg/dL. CKD was diagnosed in 70.5% of RTRs, of whom 52.9% (MDRD)/47.6% (CG) were classified as Stage III (GFR: 30-59 mL/min/1.73 m2). The agreement between the two methods was very close with regard to CKD diagnosis (kappa = 0.92) and close for stage-dependent prevalence (kappa = 0.68). The prevalence of anemia, hypocalcemia, hyperphosphatemia (HF), hyperuricemia (HU), and systemic arterial hypertension (SAH) was 10.6%, 7.6%, 10.3%, 54%, and 73.4% for patients with CKD. Significant differences were observed for HU, HF and SAH in patients without CKD. Anemia, HU and SAH were associated with CKD stage (p < 0.001).

CONCLUSION: The prevalence of CKD in the study population was high (70.5%). The two equations tested correlated closely when used for GFR estimation. Routine CKD staging in RTRs would provide patients with safer and more appropriate management.