Abstract:
Background: Chronic kidney disease (CKD) is an emerging global health burden. Precise
assessment of the estimated glomerular filtration rate (eGFR) is crucial for the accurate staging
of CKD. Different equations have been formulated based on both creatinine and cystatin C
values.
Objectives: To correlate eGFR estimated by different equations of creatinine and cystatin in
CKD patients on haemodialysis treatment.
Methods: Serum concentrations of creatinine, cystatin C and blood urea nitrogen were
measured on 40 pre-dialysis samples received at the chemical pathology laboratory at Teaching
Hospital, Karapitiya. eGFR values were calculated using creatinine-based Modification of Diet
in Renal Disease (MDRD) and three of Chronic Kidney Disease Epidemiology (CKD-EPI)
equations based on creatinine and/or cystatin C values (CKD-EPICr, CKD-EPICys C and CKD EPICr-Cys). Data were analysed using an independent sample t-test, Pearson’s correlation and
Bland Altman method using SPSS version 25.0.
Results: Of the participants (n=40), 55% were males. The mean (SD) age of study subjects was
49.6 (±13.9) years. The majority (52.5%) were within the age group 39-59 years. Mean serum
concentrations of creatinine, cystatin and blood urea nitrogen of males were 10.39 (±4.51)
mg/dL, 6.63 (±1.33) mg/L, 50.37 (±18.3) mg/dL respectively while of females were 8.59
(±3.26) mg/dL, 6.10 (±1.31) mg/L, 40.89 (±16.06) mg/dL respectively. No significant
differences in renal function parameters and eGFR values were observed gender-wise or in
different age groups (p>0.05). Bland Altman plots revealed certain level of agreement between
all selected equations, except for the values derived from CKD-EPI equations based on cystatin
C alone and creatinine-cystatin C combination (p=0.022). Person’s correlation analysis revealed
significant positive correlations between all selected equations of eGFR. The highest correlation
was observed between MDRD and CKD-EPI equations based on creatinine values (r=0.998,
p<0.001) whereas the lowest correlation was observed between MDRD and CKD-EPI equation
based on cystatin C alone (r=0.552, p<0.001).
Conclusions: The present findings suggest, creatinine-based MDRD and CKD-EPI equations in
the routine clinical setting to support the management of CKD patients on haemodialysis
treatments. The combined equation rather than the CKD-EPI equation based on cystatin C
alone, as a confirmatory tool where necessary.
