Evaluating the diagnostic value of rescaled β-trace protein in combination with serum creatinine and serum cystatin C in older adults

• Published in: Clinica chimica acta 2018-05, Vol.480, p.206-213
• Main Authors: Pottel, Hans, Schaeffner, Elke, Ebert, Natalie
• Format: Article
• Language: English
• Subjects: Beta trace protein; Cystatin C; Estimated and measured GFR; Older adults; Rescaling renal biomarker; Serum creatinine
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2018.02.026

Beta trace protein (BTP) is a novel renal biomarker that has emerged as potential alternative or addition to serum creatinine (Scr) and serum cystatin C (ScysC). We analyzed BTP's diagnostic ability to detect impaired kidney function by rescaling it and we tested whether rescaling BTP allowed us to expand the Full-Age-Spectrum (FAS)-equation to BTP. 566 participants aged ≥70 years with measured glomerular filtration rate (mGFR), Scr, ScysC and BTP from the population-based Berlin Initiative Study (BIS) were considered. We developed a single and combined FAS-equation using rescaled BTP (BTP/0.60) and calculated its sensitivity (S) and specificity (Sp) to identify kidney disease using a fixed (60 mL/min/1.73 m2) and age-dependent threshold for mGFR. Rescaled BTP shared the same reference interval with rescaled Scr and ScysC and showed acceptable diagnostic performance (S = 73.1%, Sp = 86.5%), comparable to Scr (S = 71.0%, Sp = 90.5%) and ScysC (S = 80.7%, Sp = 92.9%). Rescaled BTP can be used in the FAS-equation with comparable performance as Scr and ScysC, but the Scr/ScysC/BTP-combined FAS-eq. (P10 = 57.8%, P30 = 96.6%) did not outperform the Scr/ScysC-combined FAS-eq. (P10 = 57.1%, P30 = 96.3%). Rescaled BTP is a valid alternative to Scr or ScysC to diagnose kidney function. The FAS-concept can be applied to BTP or the combination of BTP, Scr and ScysC. •β-trace protein (BTP) has the same common normal reference interval of [0.67–1.33] as serum creatinine (Scr) and serum cystatin C (ScysC)•Subjects with rescaled renal biomarkers within the normal reference interval have normal glomerular filtration rate•impaired kidney function can be detected by all three rescaled renal biomarkers without entering them in an eGFR equation•rescaled BTP can be used interchangeably with rescaled Scr or ScysC in the Full-Age-Spectrum (FAS)-equation•the BTP/Scr/ScysC FAS-equation has improved accuracy and precision but does not outperform the Scr/ScysC-based FAS-equation