Diagnostic utility of urine protein-to-creatinine ratio for identifying proteinuria in pregnancy

Objective: To evaluate urine protein-to-creatinine ratio (UPC) alone and with uric acid and clinical factors to predict or exclude significant proteinuria in preeclampsia evaluations. Methods: Retrospective cohort study patients undergoing evaluation for preeclampsia. Greater than 300mg of protein in a 24-h collection was the gold standard defining proteinuria against which UPC performance was measured. Bivariable, multivariable, and Receiver Operating Characteristic Curve (ROC) analyses were performed. Sensitivity, specificity, predictive values, and likelihood ratios were calculated for multiple cut-points of UPC alone and with uric acid. Results: In a cohort of 356 patients, the area under the curve for UPC in the diagnosis of proteinuria was 0.81. No single cut-point of UPC was diagnostic of preeclampsia. UPC values ≤0.08 or ≥1.19 have useful negative or positive predictive values of 86% and 96%. Uric acid and clinical factors did not improve the detection of significant proteinuria. Conclusion: Extreme values of UPC ratio ≤0.08 or ≥1.19 have favorable predictive values, which could enable the rapid diagnosis of preeclampsia without a 24-h urine collection.