GFR Estimation Using β-Trace Protein and β2-Microglobulin in CKD

Area of Science:

• Nephrology
• Biomarkers
• Renal Function Assessment

Background:

• β-Trace protein (BTP) and β2-microglobulin (B2M) are emerging biomarkers for glomerular filtration.
• These markers show stronger associations with adverse outcomes compared to creatinine.
• Development of robust glomerular filtration rate (GFR) estimating equations for BTP and B2M is limited.

Purpose of the Study:

• To develop and evaluate GFR estimating equations using BTP and B2M.
• To compare the performance of BTP and B2M based GFR equations with existing creatinine and cystatin C equations.
• To assess the influence of demographic factors (age, sex, race) on BTP and B2M compared to creatinine and cystatin C.

Main Methods:

• Diagnostic test accuracy study utilizing a pooled database of 3,551 participants with chronic kidney disease (CKD).
• GFR was estimated using equations derived from creatinine, cystatin C, BTP, or B2M levels.
• Measured GFR served as the reference standard, determined by urinary iothalamate clearance.

Main Results:

• BTP and B2M showed smaller coefficients for age, sex, and race compared to creatinine, and similar or smaller coefficients compared to cystatin C.
• Individual BTP or B2M based GFR equations were less accurate than CKD-EPI creatinine or cystatin C equations.
• A combined BTP-B2M equation demonstrated accuracy comparable to CKD-EPI creatinine or cystatin C equations.

Conclusions:

• While BTP and B2M are less affected by demographic variables than creatinine, their standalone GFR estimation accuracy is lower than current CKD-EPI equations.
• The development of CKD-EPI equations incorporating BTP and B2M represents a methodological advancement for studying these filtration markers.
• Further investigation is necessary before BTP and B2M can be implemented in clinical practice for GFR estimation.