The correlation and consistency between the spot time urine protein to creatinine ratio and urine protein quantification (24h) in lupus nephritis
10.3760/cma.j.cn141217-20241224-00376
- VernacularTitle:点时间尿蛋白肌酐比与尿蛋白定量（24 h）在狼疮肾炎中的相关性和一致性研究
- Author:
Yamin LI
1
;
Tingting DING
1
;
Dai GAO
1
;
Xiaohui ZHANG
1
;
Zhuoli ZHANG
1
Author Information
1. 北京大学第一医院风湿免疫科，北京 100034
- Publication Type:Journal Article
- Keywords:
Lupus nephritis;
Urinary protein creatinine ratio;
24-hour urinary protein quantification;
Correlation;
Consistency
- From:
Chinese Journal of Rheumatology
2025;29(10):839-845
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the correlation and consistency of urine protein creatinine ratio (UPCR) with 24-hour urine protein quantification (24hUTP) in patients with lupus nephritis (LN).Methods:LN patients were enrolled from the STAR cohort of Peking University First Hospital, The time period is January 1, 2007 to July 31 2024. The correlation and consistency of UPCR with 24hUTP were analyzed in overall patients and various subgroups, such as,the levels of proteinuria and multiple parameters. The correlation was analyzed using Spearman′s method. The consistency was evaluated by using Kappa test, cross tabulation consistency probability, and UPCR/24hUTP ratio.Results:A total of 261 LN patients were included in this study. Overall, UPCR was positively correlated with 24hUTP ( r=0.892, P<0.001), and the consistency between then was good ( Kappa=0.603, P<0.001). Subgroup analysis based on multiple levels including different urine volume, eGFR grading, albumin, urea nitrogen, total cholesterol, low-density lipoprotein cholesterol, SLEDAI-2K, also revealed good correlation ( r=0.747~0.951; P<0.001) and consistency ( Kappa=0.393~0.771; P<0.001). Patients were divided into subgroups according to the 24hUTP (≤ 0.5 g, >0.5 g to ≤1.0 g, >1.0 g to ≤3.5 g, and>3.5 g). The best correlation and consistency were observed in ≤ 0.5g group ( r=0.728, Kappa=0.395, P<0.001), while the correlation was average or poor in other subgroups ( r=0.16~0.46). The consistency evaluated by UPCR/24hUTP ratio showed good consistency (ratios between 0.8~1.2) in 74 patients (28.4%), however, the unsatisfactory consistency in most patients, with 128 patients (68.4%) having ratios < 0.8, indicating a significantly lower UPCR than 24hUTP, and 59 patients (31.6%) having ratios > 1.2, indicating significantly higher UPCR than 24hUTP.The cross tabulation evaluation showed that the probability of consistency was distributed in a gradient, we found the worst consistency (48.9%) in >0.5 g to ≤1.0 g group, moderate consistency (64.0%) in >1.0 g to ≤3.5 g group, and the best consistency (73.3%) in >3.5 g group. Conclusion:In LN patients, the overall correlation and consistency between UPCR and 24hUTP are good, but the degree of correlation and consistency is closely related to the total amount of proteinuria. When 24hUTP ≤ 0.5 g, UPCR can be used to replace 24hUTP, but UPCR cannot be simply equated with 24hUTP at other urinary protein levels. Detecting 24hUTP to accurately reflect the total amount of proteinuria remain necessary.
