MO419: Many Faces of Non-Proteinuric CKD—A Cluster-Analysis-Based Observation

Abstract

Abstract BACKGROUND AND AIMS With a global expansion of the elderly population, physicians encounter a growing number of chronic kidney disease (CKD) patients who have no or only a minimal amount of proteinuria. However, those patients are not clinically uniform; some quickly develop into a progressive loss of kidney function while others stay in their CKD stages for years or even over a few decades. The purpose of this study is to distinguish high-risk non-proteinuric CKD patients whose estimated glomerular filtration rate (eGFR) decline is faster than others. METHOD A hospital-wide study with all the laboratory data for a period of 4 years and 2 months was performed. Non-dialysis CKD patients (median eGFR < 60 mL/min/1.73m2) with ≥18 years in whom the eGFR slope was obtained over 731 days or more were retrieved, then the patients with a median of dipstick proteinuria of less than 1+, i.e. (−) or (±), were included for analysis. An eGFR slope/patient was calculated by at least three eGFR measurements over time. Medians were used for each laboratory datum, including dipstick proteinuria and haematuria (both changed to numeric variables, e.g. 1 + into 1.0), blood cell count and serum chemistry. Cluster analyses, hierarchical and k-means, were performed. Statistical analysis was done with R 3.6.0 on Ubuntu. Missing values were imputed by an R package {mice}. RESULTS A total of 905 patients [Male: Female = 395:510, age 75.7 ± 10.4 (34–101, median 76 years)] were analysed whose median eGFR was 49.6 ± 9.34 (14.4–59.9, median 52.6) mL/min/1.73m2. A hierarchical cluster analysis was initially performed so a group count of 5 was suggested to be appropriate. Then performed was a k-means cluster analysis which identified 5 clusters; Cluster 1 was a group of patients with the least progressive CKD, whereas Cluster 5 had the fastest decline in eGFR. Cluster 5 had background features such as higher blood leukocyte count, higher blood urea nitrogen, higher red cell distribution width and less serum albumin, compared with other clusters. Cluster 2 also had modestly higher blood leukocyte count, Cluster 3 had lower haemoglobin, and Cluster 4 had higher serum uric acid; Cluster 3 had a variable speed of decline in eGFR. CONCLUSION Non-proteinuric CKD patients are not uniform but are variable in the clinical background as well as in the speed of CKD progression. They are better be treated according to the estimated risks for each patient.