Glomerular Filtration Rate Estimation Using β2-Microglobulin and β-Trace Protein in Adults With Solid Tumors: A Prospective Cross-Sectional Study

Abstract

β2-microglobulin (B2M), and β-trace-protein (BTP) are novel endogenous filtration markers that may improve the accuracy of estimated glomerular filtration rate (eGFR) beyond creatinine and cystatin C (eGFRcr-cys), but they have not been assessed in patients with cancer. Cross-sectional analysis. Prospective cohort of 1,200 patients with active solid tumors recruited between April 2015 and September 2017. CKD-EPI equations without race combining B2M and/or BTP with creatinine with or without cystatin C (2-, 3- or 4-marker panel eGFR). Performance of equations compared to eGFRcr-cys. Non-GFR determinants of serum B2M and BTP (SB2M, and SBTP, respectively). mGFR was determined using the plasma clearance of 51Cr-EDTA. Bias was defined as the median of the differences between mGFR and eGFR. 1-P30 was defined as the percentage of estimates that differed by more than 30% from the mGFR (1-P30). Linear regression was used to assess association of clinical and laboratory variables with SB2M, and SBTP after adjustment for mGFR. Mean (SD) age and mGFR were 58.8 (13.2) years and 78.4 (21.7) ml/min/1.73 m2, respectively. Performance of the 3-marker and 4-marker panel equations was better than eGFRcr-cys (lesser bias and 1-P30). Performance of 2-marker panel equations was as good as eGFRcr-cys (lesser bias and similar 1-P30). SB2M and SBTP were not strongly influenced by cancer site. Participants may have had better clinical performance status than the general population of patients with solid tumors. B2M and BTP can improve the accuracy of eGFR and may be useful as confirmatory tests in patients with solid tumors, either by inclusion in multi-marker panel equation with creatinine and cystatin C, or by substituting for cystatin C in combination with creatinine.