Reliability and validity of a new baseline renal function calculator after radical nephrectomy in a Malaysian population

Purpose: This study aimed to determine the reliability and validity of a new baseline renal function calculator after radical nephrectomy in Malaysian patients. Materials and Methods: This study retrospectively collected data on patients' demographics, tumor characteristics, and baseline estimated glomerular filtration rate (eGFR) during radical nephrectomy from a single urology center from 2015 to 2020. The predicted eGFR was determined using a calculator. Predicted eGFR was validated by performing simple linear regression and Pearson coefficient correlations; reliability was determined by calculating Shrout and Fleiss's intraclass correlation coefficients. Results: Fifty-two patients (mean age, 57.5 years) were enrolled in this study. Thirty-seven (71.2%) patients were men, and 15 (28.8%) had diabetes. Most of the patients (90.2%) had a baseline eGFR of >60 mL/min/1.73 m2. The mean preoperative eGFR was 85.33 mL/min/1.73 m2, whereas the mean postoperative eGFR was 59.88 mL/min/1.73 m2. Simple linear regression analysis resulted in an R2 value of 0.700. The predicted eGFR was significantly correlated with the actual eGFR 6 months after radical nephrectomy (r = 0.837, P < 0.0001). The intraclass correlation coefficient value of 0.83 indicated good reliability of the formula. Conclusion: Our new validated and reliable baseline renal function calculator can provide easy and rapid prediction of renal function in patients scheduled for radical nephrectomy in a sample Malaysian population.