The Urinary Protein-to-Creatinine Ratio in Canadian Women at Risk of Preeclampsia: Does the Time of Day of Testing Matter?

A meta-analysis on diagnostic accuracy of spot urinary protein to creatinine ratio versus 12-h proteinuria in preeclampsia

To systematically review the diagnostic accuracy of spot urinary protein to creatinine ratio (PCR) and 12-h proteinuria in preeclampsia and to estimate which is a preferred alternative method for 24-h proteinuria, we carried out this meta-analysis. 25 primary studies were included based on searching strategy. For spot urinary PCR, our results showed pooled sensitivity of 87% (95% confidence interval [CI] 83%-91%) and specificity of 86% (95% CI 79%-91%), with an area under curve (AUC) of 0.93 (0.90-0.95). For 12-h proteinuria, pooled sensitivity and specificity were 92% (95% CI 87%-96%) and 99% (95% CI 75%-100%), respectively, with an AUC of 0.97 (0.95-0.98). Fagan plot and likelihood ratio scattergram showed that 12-h proteinuria yielded a better discriminatory performance on diagnosis of proteinuria (≥0.3 g/24 h). These results indicated that 12-h proteinuria estimation shows better clinical value than spot urine PCR for diagnosis of preeclampsia. However, due to the severity of condition and the fact that preeclampsia patients cannot wait for 12 h, spot urine PCR can be used as one of the diagnostic indicators.

Comparison of random urine protein/creatinine ratio with 24-hour urine protein in suspected pre-eclampsia

Introduction

Proteinuria is one of the classical criteria for the diagnosis of pre-eclampsia. The gold standard remains the measurement of 24-h urine protein which is time consuming and prone to preanalytical errors. Random urine protein creatinine ratio (UPCR) is endorsed by clinical practice guidelines as a faster alternative. The aim of this study was to evaluate the correlation between the 24-h urine protein excretion and UPCR in the identification of proteinuria in suspected preeclamptic patients.

Method

A total of 51 women with suspected pre-eclampsia from the maternal fetal clinic of our institution were retrospectively studied. The correlation between the UPCR in random urine samples and protein excretion in the 24-h urine collection was determined by Deming Regression analysis and Pearson correlation on EP evaluator and SPSS respectively.

Result

There was a significant positive correlation between the numerical values obtained by 24-h urine protein and the UPCR (R = 0.88, P < 0.001). Concordance analysis showed 81.1% positive agreement for proteinuria between methods (>300 mg/24hr and >0.3) and 71.4% negative agreement. The clinical sensitivity and specificity of the UPCR was 74% and 69% respectively.

Conclusion

Overall, UPCR was well correlated with 24-h urine protein and could be an effective and compliant screening tool to indicate proteinuria in preeclamptic patients.

Urinary Angiotensinogen-Melatonin Ratio in Gestational Diabetes and Preeclampsia

Background: A large research portfolio indicates that an activated renal renin-angiotensin system or a deficit on melatonin is associated with several cardiovascular pathologies. In this observational clinical study, we hypothesized that alterations in urinary melatonin or angiotensinogen levels may be altered in two common conditions, preeclampsia and gestational diabetes. Our study’s primary objective was to assess melatonin and angiotensinogen as novel disease biomarkers detectable and quantifiable in the urine of pregnant women with or without pregnancy complications.

Methods: This was a concurrent cohort study of pregnant women with selected obstetric pathologies (gestational diabetes, preeclampsia, hypertension and obesity with hypertension). A group of healthy controls was also included. Urinary 6-sulfatoxymelatonin and angiotensinogen were measured by sensitive and specific ELISAs in first morning void urine samples. The patients were included in the cohort consecutively, and the diagnosis was blinded at the level of urine collection. Urinary 6-sulfatoxymelatonin and angiotensinogen levels were investigated in the patients included in the cohort.

Results: Urinary levels of angiotensinogen were significantly higher in the gestational diabetes [angiotensinogen/creatinine ratio median (25th, 75th): 0.11 (0.07, 0.18)] and preeclampsia [0.08 (0.06, 0.18)] groups than in those with healthy pregnancy [0.05(0.04, 0.06]; 6-sulfatoxymelatonin levels were significantly lower in the gestational diabetes [ug/h: median (25th, 75th): 0.12(0.08, 0.17)] and preeclampsia [0.12 (0.09, 0.15)] groups than in those with healthy pregnancy [0.20 (0.15, 0.27]. Neither morning void protein/creatinine ratio nor 24-h urine protein estimate were significantly different between the study groups.

Conclusion: These results suggest that urinary angiotensinogen levels may indicate an intrarenal RAS activation while melatonin production appears to be defective in gestational diabetes or hypertension. An angiotensinogen/melatonin ratio is suggested as an early biomarker for identification of gestational diabetes or hypertension. This report provides a basis for the potential use of melatonin for the treatment of preeclampsia. A prospective study in a larger number of patients to determine the operative characteristics of these markers as potential diagnostic tests is justified.

Protein-creatinine ratio and albumin-creatinine ratio for the diagnosis of significant proteinuria in pregnant women with hypertension: Systematic review and meta-analysis of diagnostic test accuracy

BACKGROUND

The gold standard for assessment and diagnosis of significant proteinuria in pregnancy has been by 24-hour urine collection and analysis. Determining fast, accurate methods to identify clinically significant proteinuria would aid diagnosis of pre-eclampsia. The objective of this study was to determine the accuracy of spot protein-creatinine ratio (PCR) and albumin-creatinine ratio (ACR) measurements compared with 24-hour urine collection for the identification of clinically significant proteinuria in women with hypertensive disorders of pregnancy.

METHODS

Search strategies were developed for electronic databases from inception to 1st October 2020. Data were assessed for methodological quality using the QUADAS-II checklist for risk of bias and quality of the evidence using GRADE. Meta-analysis was performed where there were at least four studies presenting data for the same comparison (test and threshold). This is an update of the review for NICE guideline NG133 (published June 2019) and includes additional data.

RESULTS

Twenty-nine studies were included. PCR measurements (28 studies) showed high sensitivity (91%) and specificity (89%) at a threshold of 30 mg/mmol (n = 3577). Higher thresholds (>60 mg/mmol) increased specificity, but reduced sensitivity. At a threshold of PCR 30 mg/mmol, diagnostic accuracy improved for sensitivity and specificity (93% for both) in studies where the first morning void was excluded (n = 1868). Data available (4 studies) for ACR supports ruling out of significant proteinuria at less than 2 mg/mmol, though evidence was limited by paucity of data and wide confidence intervals around the result.

CONCLUSIONS

PCR and ACR have high accuracy compared to the gold standard 24-hour urine collection.

Management of pregnancies with suspected preeclampsia based on 6-hour vs 24-hour urine protein collection-a randomized double-blind controlled pilot trial

BACKGROUND

Traditionally, the diagnosis of preeclampsia requires elevated blood pressure measurements and proteinuria demonstrated in a 24-hour urine collection. This prolonged urine collection is associated with patient discomfort, a delay in diagnosis, and in some cases, hospitalization for further management of outcomes.

OBJECTIVE

We aimed to assess the feasibility, reliability, and association between maternal and neonatal outcomes of pregnancies managed according to a 6-hour vs 24-hour urine protein collection for suspected preeclampsia.

STUDY DESIGN

This was a randomized controlled trial conducted at a tertiary university hospital between January 2019 and January 2021 (ClinicalTrials.gov Identifier: NCT03724786). Patients who were hospitalized for preeclampsia workup were asked to participate and randomized at a 1:1 ratio to 6- and 24-hour urine protein collection groups. Both groups collected urine for 24 hours, during which the collection was also tested after 6-hours. After 24 hours, both results were reviewed by one of the research staff, and either the 6- or 24-hour collection result was reported to the patient's managing physician and was documented in the patient's medical record. Both patient and the managing physician were blinded to group allocation. Unblinding was undertaken in cases of a discrepancy between the results (1 of 2 results of >300 mg protein), and the results were analyzed by intention to treat. The primary study outcome was defined as a composite of adverse maternal outcomes. The sample size was set empirically as per proof on concept design.

RESULTS

During the study period, 115 patients participated in the trial, 101 of whom completed the follow-up and were analyzed-51 in the 6-hour group and 50 in the 24-hour group. Patient demographics were similar between the study groups. Unblinding occurred in 7 cases in the 6-hour group, in which the initial 6-hour result ranged from 168 to 475 mg. The rates of composite adverse maternal outcomes were 15.6% and 12.0% in the 6- and 24-hour groups, respectively (P=.59). No significant difference was demonstrated in the rate of adverse neonatal outcomes, cesarean delivery, induction of labor, gestational age at delivery, betamethasone treatment, or neonatal birthweight.

CONCLUSION

Managing pregnancies suspected of preeclampsia with a 6-hour urine protein collection is feasible and associated with similar maternal and neonatal outcomes. In cases where the 6-hour result is in the 168 to 475 mg range, we propose completing a 24-hour collection.

Spot urine protein-to-creatinine ratio as a diagnostic test in pre-eclampsia: A gold standard?

OBJECTIVE

To determine the diagnostic accuracy and optimal threshold of the spot protein-to-creatinine ratio (PCR) compared to the gold standard, 24-hour proteinuria (24HP) in patients with suspected pre-eclampsia.

METHODS

A prospective observational study was performed from June 2015 to May 2017 consisting of patients hospitalized for suspected pre-eclampsia in a tertiary care referral center. To compare the two diagnostic tests, a spot urine sample was obtained to perform the PCR before starting the collection of the 24HP. Only patients who had both tests were analyzed.

RESULTS

In total, 148 patients (216 samples) were included. The two tests were highly correlated (r=0.80, P<0.001). The receiver operating characteristic curve analysis and the area under the curve (AUC=0.92) highlighted the accuracy of PCR in diagnosing significant proteinuria and thus pre-eclampsia. The optimal cut-off using the Liu method was 56.9 mg/mmol (sensitivity=79.3%, specificity=91.5%).

CONCLUSION

The results suggest that PCR could replace 24HP when diagnosing proteinuria in pre-eclampsia. Moreover, it is a simple test, easy to realize and standardize, and cheap with no need for systematic hospitalization. The best cut-off should be chosen by thinking about the risks for adverse maternal and/or fetal outcomes. The test may help to optimize medical care in pre-eclampsia worldwide.

[Spot urinary protein to creatinine ratio: Which role in preeclampsia diagnosis?]

Preeclampsia remains a serious and feared complication of pregnancy. Its diagnosis is confirmed upon detection of hypertension and significant proteinuria starting from 20 weeks of gestation. The 24-hour urine collection is considered to be the gold standard test for quantitative diagnosis of proteinuria despite its downsides. Recent studies have brought into question its accuracy during pregnancy as complete samples are hard to get, but above all, as this time consuming procedure often delays treatment and may preclude optimal management. Several publications looked at the spot urinary protein to creatinine ratio (PCR) as a replacement to the 24-hour urine collection. Largely used outside pregnancy, this fast and less invasive test seems a compelling alternative. In this paper, data from previous meta-analysis and guidelines have been reviewed in an attempt to clarify the role of the PCR in clinical practice and elaborate an algorithm in case of suspicion of preeclampsia. Thus, this test seems a valid "rule-out test" when using the optimal threshold of 30mg/mmol. Higher values require a 24-hour urine collection for confirmation.