A point-of care urine test to predict pre-eclampsia development in Asian women with suspected pre-eclampsia

To evaluate the diagnostic performance and clinical utility of the urine Congo red dot test (CRDT) in predicting pre-eclampsia (PE) within 7 days, 14 days and 28 days of assessment. A prospective single centre double blind non-intervention study conducted from January 2020 to March 2022. Urine congophilia has been proposed as a point-of-care test for the prediction and rapid identification of PE. In our study, urine CRDT and pregnancy outcomes were assessed in women presenting with clinical features of suspected PE after 20 weeks of gestation. Among the 216 women analysed, 78 (36.1%) women developed PE, in which only 7 (9.0%) of them had a positive urine CRDT test. The median (IQR) interval between the initial test and the diagnosis of PE was significantly shorter for women with a positive urine CRDT compared with women with a negative urine CRDT (1 day (0-5 days) vs. 8 days (1-19 days), P = 0.027). The negative predictive value of a negative urine CRDT test for PE within 7 days, 14 days and 28 days of assessment were 83.73% (95%CI 81.75%- 85.54%), 78.92% (95% confidence interval [CI] 77.07%- 80.71%) and 71.77% (95%CI 70.06%- 73.42%) respectively. The sensitivity of the urine CRDT in ruling in PE within 7 days, 14 days and 28 days of assessment were 17.07% (95%CI 7.15%- 32.06%), 13.73% (95%CI 5.70%- 26.26%) and 10.61% (95%CI 4.37%- 20.64%), respectively. Urine CRDT alone has low sensitivity in the short-term prediction of PE in women with suspected PE. Further studies are required to evaluate its clinical utility combined with maternal serum antiangiogenic and pro-angiogenic proteins in improving the short-term prediction of PE.