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CKD PATIENTS WITHOUT SIGNIFICANT PROTEINURIA — WHAT ARE THE RISK FACTORS FOR PROGRESSIVE RENAL DISEASE?

INTRODUCTION AND AIMS: CKD patients without significant proteinuria are largely considered to have their eGFR decline slower than proteinuric patients have. Nevertheless many of those patients have progressive renal diseases, often eventually reaching ESRD. Little is known about prognostic factors of CKD in patients without significant proteinuria. The purpose of this study is to discriminate high-risk CKD patients, especially in populations without significant proteinuria.

METHODS: As a hospital-wide survey, a whole set of laboratory tests were retrieved over 26 months (from October 2015 to December 2017). Patients with at least 3 measurements of eGFR over more than 365 days, with an averaged eGFR of less than 50 mL/min/1.73m2, were collected; then an eGFR slope was calculated for each patient. For the assessment of proteinuria, a dipstick urine protein determination was considered to better represent the real-world clinics for all the subspecialities in the Hospital; numbers of 0, 0.5, 1, 2, 3 or 4 were applied to (-), (+-), (1+), (2+), (3+) or (4+) respectively, then the numbers were averaged during the study period (avUprot); urinalysis was done on an average of 8.2 (median, 7) times per patient. Dipstick was done in 388 patients while U-protein/U-creatinine ratio (Up/Ucr) was measured in 236 patients; an excellent relation between them was confirmed (Up/Ucr = -0.346 + 1.185*avUprot [p<0.0001]). All the laboratory values including serum albumin and LDH were equally averaged during the study period for each patient.

RESULTS: A total of 436 patients (age 33-101 (median, 79); M:F = 205:229) met the entry criteria, with their eGFR 8.1 - 49.9 (median, 41.3) mL/min/1.73m2 and with the eGFR slope of -51.3-18.6 (m±SD, -1.80±5.90; median -1.26) mL/min/1.73m2/year. A univariate analysis showed significant association of the eGFR slope with avUprot, plasma leukocytes (WBCs), serum albumin and LDH. A stepwise multivariate analysis suggested the following equation: the predicted eGFR slope = 0.026 - 0.469 [(WBCs-6000)/2000]^2 - 0.393*avUprot [p<0.0001]. In the subgroup analysis in patients without significant proteinuria (i.e., avUprot less than 1.0; n=279, age 46-101 (median, 79), M:F = 131:148), WBC was again significantly associated with eGFR slope [stepwise multivariate analysis; p = 0.021].

CONCLUSIONS: Plasma leukocytosis might herald a worse renal prognosis in CKD patients.