Abstract: SA-PO428

Existing Creatinine Based Estimating Equations Overestimate GFR in Indian Subjects

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 302 CKD: Estimating Equations, Incidence, Prevalence, Special Populations

Authors

  • Kumar, Vivek, Postgraduate Institute of Medical Education and Research, Chandigarh, India
  • Yadav, Ashok Kumar, Postgraduate Institute of Medical Education and Research, Chandigarh, India
  • Yasuda, Yoshinari, Nagoya University Post Graduate School of Medicine, Nagoya, Japan
  • Kumar, Vinod, Fienstine Institute for Medical Research, New York, New York, United States
  • Gupta, Krishan Lal L., Postgraduate Institute of Medical Education & Research, Chandigarh, India
  • Horio, Masaru, Osaka University Graduate School of Medicine, Ashiya, Japan
  • Jha, Vivekanand, George Institute for Global Health, New Delhi, India
Background

Ethnic differences, predominantly vegetarian diet and poor representation in derivation and validation cohorts for eGFR equations call for assessment of accuracy of current eGFR equations in Indian population.

Methods

This study was done at PGIMER, Chandigarh, India. Stable adult prospective living renal donors or subjects with CKD were eligible for enrolment. GFR was measured (mGFR) by urinary clearance of inulin. eGFR were calculated using CKD-EPICr, Japanese coefficient-modified CKD-EPI, MDRD and CKD-EPI Pakistan equation. Bias (mGFR-eGFR), 95% limits of agreement, precision (95% CI of mGFR-eGFR) and accuracy (RMSE of mGFR-eGFR, and % of subjects with eGFR within ±30% of mGFR i.e. P30] were calculated.

Results

After excluding 5 subjects with incomplete data, 130 subjects were included for final analyses (63 prospective donors and 67 subjects with previously diagnosed CKD). 50% were strict vegetarian and average meat intake among meat eaters was only 3.8 times/month. The average creatinine (Cr) excretion was 14.7 mg/kg/day (95% CI: 13.5 to 15.9 mg/kg/day) and 12.4 mg/kg/day (95% CI: 11.2 to 13.6 mg/kg/day) in males and females, respectively. The average daily protein intake based on 24-hour urea nitrogen excretion was 46.1 g/day (95% CI: 43.2 to 48.8 g/day), respectively. Bias, precision and accuracy of eGFR equations are shown in table 1. All Cr based eGFR equations overestimated GFR with CKD-EPICr and MDRD being the poorest.

Conclusion

Cr based eGFR equations significantly overestimate GFR in the predominantly vegetarian Indian population. Lower Cr excretion suggest that this overestimation is likely linked to lower muscle mass. There is need of an appropriately powered study to develop either a correction factor or a new equation for accurate assessment of kidney function in Indian population.

Table 1: Performance of GFR estimating equations as compared to measured GFR by urinary inulin clearance
eGFR equationBias (mGFR-eGFR)
(ml/min/1.73m2)
95% Limits of agreement
(ml/min/1.73m2)
Precision (95% CI)
(ml/min/1.73m2)
Accuracy RMSE
(ml/min/1.73m2)
Accuracy P30 (%)
CKD-EPICr-24.92±17.17-58.57 to 8.73-27.90 to -21.9530.2222.3
CKD-EPI (PK)-16.84±15.39-47.00 to 13.32-19.52 to -14.1747.7239.2
CKD-EPI (JAP)-10.62±13.07-47.00 to 13.32-12.87 to -8.3316.7951.5
MDRD-31.01±25.33-80.60 to 18.59-35.41 to -26.6239.9816.2

Funding

  • Private Foundation Support