Estimation of 24-hour urine protein excretion using urine albumin-to-creatinine ratio
Abstract Background There is still a lack of quantitative description of the relationship between urine albumin-to-creatinine ratio (ACR) and 24-hour urine protein excretion (24h UPE). We aimed to study the correlation between 24h UPE and urine ACR and develop a prediction model for 24h UPE employing urine ACR. Methods This was a retrospective and observational study. All individuals with same-day urine ACR and 24h UPE tests in Sichuan Provincial People’s Hospital from September 1, 2018 to December 31, 2019 were enrolled in the study. Correlation and agreement between urine ACR and 24h UPE were evaluated. A prediction model of 24h UPE was developed and validated. Results 671 subjects were identified. Urine ACR correlated well with 24h UPE (Pearson’s coefficient after natural logarithm transformation = 0.908; p<0.001) and the agreement was consistently good (overall ICC = 0.938; 95% CI: 0.928-0.947; p<0.001). Our multivariable transform model had good performance (R 2 =0.869) and high accuracy (RMSE=0.690) to estimate 24h UPE less than 10 g/day. Conclusions Urine ACR correlates well with 24h UPE in a general population. Our prediction model is an useful tool for estimating 24h UPE less than 10 g/day, however, 24h UPE is still mandatory in situation when the majority of proteinuria is of tubular origin.