Comparing estimated protein excretion rate and spot urinary protein-creatinine ratio in assessing urinary protein excretion in patients with kidney disease in China: a single center study.

Abstract

Objectives: This study aimed to analyze the potential of the estimated protein excretion rate (ePER) as a substitute for the spot urinary protein-creatinine ratio (uPCR) in clinical reports for accurately assessing urinary protein excretion in China.

Methods: We included 1721 patients in the study and compared the differences in levels, correlation, bias, methodological evaluation between uPCR, ePER, and 24-h urinary protein.

Results: Significant differences (Z = -17.568, p < 0.001) were found between uPCR and 24-h urine protein levels in all cases. However, no statistically significant difference (Z = -0.652, p = 0.514) was found between ePER and 24-h urine protein. The bias analysis revealed that the negative bias rate between ePER and 24-h urine protein was -4.33%, significantly lower compared to uPCR (-30.88%). Incorporating ePER significantly boosted its sensitivity to 91.3% in this cohort. Furthermore, ePER demonstrated a higher correlation (r = 0.74, p < 0.001) and kappa consistency (κ = 0.802, p = 0.015) with 24-h urinary protein compared to uPCR (r = 0.71, p < 0.001; κ = 0.737, p = 0.016). However, in the >65 age group, those with estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73m² group and spot urinary creatinine <500 mg/L exhibited a higher ePER bias compared to uPCR.

Conclusion: These findings highlight the potential of ePER as a valuable tool for accurately assessing urinary protein excretion. Nonetheless, its limitations should be considered, especially in specific patient populations.