Ann Lab Med.  2018 May;38(3):261-265. 10.3343/alm.2018.38.3.261.

Evaluation of the 1B Equation to Estimate Glomerular Filtration Rate in Pediatric Patients with Cancer

• Jeong TD
• Kim J
• Lee W
• Chun S
• Hong KS
• Min WK

• KMID: 2403461
• DOI: http://doi.org/10.3343/alm.2018.38.3.261

Abstract

The 1B equation is recommended for calculating the glomerular filtration rate (GFR) in children. Since few reports have evaluated the performance of the 1B equation, we investigated the performance of estimated GFR (eGFR) equations with the blood urea nitrogen (BUN) variable for pediatric cancer patients. In total, 203 children with cancer who underwent measured GFR (mGFR) assessment were enrolled. The median (range) mGFR and eGFR calculated using the updated Schwartz equation were 118 (43-241) and 135 (34-257) mL/min/1.73 m², respectively. The bias, precision (root mean square error [RMSE]), and accuracy (P30, mGFR±30%) of three eGFR equations including updated Schwartz, 1B, and full age spectrum (FAS) were compared. The median bias (mL/min/1.73 m²) was: updated Schwartz, 8.5; 1B, −9.0; and FAS, 4.2. The biases for all three eGFR equations were significantly different from zero. The P30 was: updated Schwartz, 63.5%; 1B, 66.0%; and FAS, 66.0%. The RMSE was the lowest for the 1B equation (40.4), followed by FAS (42.3), and updated Schwartz (45.5). The median eGFR/mGFR ratio for the eGFR equations decreased with age and reduced kidney functions (i.e., increased creatinine and BUN concentrations). The bias may be further reduced by using the average from two equations, such as the updated Schwartz and 1B, or FAS equation, rather than using the updated Schwartz or 1B equation alone. The use of the 1B equation may underestimate the GFR. Using creatinine and BUN variables in the eGFR equation may yield a more accurate estimate of the GFR in pediatric cancer patients.

Keyword

1B; Blood urea nitrogen; Children; Creatinine; full age spectrum; Glomerular filtration rate; updated Schwartz

MeSH Terms

Bias (Epidemiology)
Blood Urea Nitrogen
Child
Creatinine
Glomerular Filtration Rate*
Humans
Kidney
Creatinine

Figure

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  Fig. 1 Median ratio of eGFR to mGFR was stratified by (A) age, (B) height, (C) serum creatinine, and (D) blood urea nitrogen. Black solid line (○), updated Schwartz equation; black dotted line (▵), FAS equation; black dashed line (□), 1B equation; and gray line, the reference line (eGFR/mGFR ratio of 1.0).Abbreviations: eGFR, estimated glomerular filtration rate; FAS, full age spectrum; mGFR, measured glomerular filtration rate. See Supplemental Data Table S1 for detailed numerical values (median and interquartile ratios).

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