Agreement between the CKD-EPI serum creatinine- and cystatin C- based eGFR equations in pregnant and non-pregnant women: A cross-sectional study in Ghana

Abstract

Introduction: The serum cystatin C (sCys)-based estimated glomerular filtration rate (eGFRcys) is usually preferred to that of serum creatinine (eGFRcrt). However, the former is relatively more costly and may not be suitable for low- and middle-income countries such as Ghana. The study sought to determine the agreement between the sCrt- and sCys-based eGFR in pregnant and non-pregnant.

Materials and Methods: This was a cross-sectional study conducted from May 2020 to April 2022 in the Upper East Regional and War Memorial Hospitals. The study involved 281 women, 50 of whom were non-pregnant (nonP) and 231 of whom were normotensive pregnant (NP). Serum Crt and Cys were measured using a routine biochemistry analyzer and ELISA, then used to calculate the eGFR based on the CKD-EPI equations.

Results: A percentage difference in eGFR (bias) <40% was considered a measure of high agreement between the two methods. The sCrt was significantly higher (P<0.001), while eGFRcrt was significantly lower (P=0.001) in the normotensive pregnant women. The eGFRcys were significantly higher than eGFRcrt and the combined (eGFRcrt+cys) in both non-pregnant and pregnant women (P<0.001). There was no high agreement between eGFRcrt and eGFRcys (bias: -61% to -76%). Reduced eGFR (<60 mL/min/1.73m2) was detected only by effort with a frequency of 4.7% and 2.0% in pregnant and non-pregnant women, respectively.

Conclusion: There is a marked difference in eGFR based on Crt and Cys in pregnant and non-pregnant women. The sCrt—and sCys-based CKD-EPI equations need to be validated in a given population before use.