Comparing urine point-of-care tests to screen preeclampsia: Congo-red dot paper test versus dipstick urinalysis

To compare the urine Congo-red dot paper test (CRD) with dipstick urinalysis to screen preeclampsia (PE). A total of 409 paired spot urine samples were obtained prospectively from women with suspected pre-eclampsia attending for routine hospital visits. Congo-red dot paper test and dipstick urinalysis were examined and compared to screen pre-eclampsia. The agreement between the two urinary test is modest (kappa coefficient = 0.28, 95% CI 0.14-0.42). The specificity of CRD was higher than urinalysis (97.4% vs. 90.4%, p < .001). Urinalysis performed better in sensitivity (77.3% vs. 40.9%, p = .04) and the area under the receiver operating characteristic curves (AUC) (0.84 [95% CI 0.74-0.94] vs. 0.69 [95% CI 0.55-0.83], p = .04) than CRD, respectively. The sensitivity, specificity, AUC of the parallel test of them is 86.4% (64.0%-96.4%), 89.1% (85.5%-92.0%), and 0.88 (95% CI 0.79-0.96). And the serial test is 31.8% (14.7%-54.9%), 98.7% (96.8%-99.5%), 0.65 (95% CI 0.51-0.79), accordingly. The urinalysis is a better diagnosing test for preeclampsia. CRD could aid in the diagnosis of patients with preeclampsia. Combined the two tests in suspected patients may further improve the performance in the diagnosis of preeclampsia. Further study need to be made for its potential clinical practice.