Validation of urinary Congo Red preeclampsia detection point-of-care devise

Objectives: To evaluate a commercial a Congo Red urine devise for assessing preeclampsia risk.

Study design: Prospective non-intervention study among women presenting with clinical suspicion of preeclampsia. The devise was used at the time of enrolment and, depending on gestation, on 1-3 later occasions.

Outcome measures: Abnormal diffusion patterns classified as positive or negative, in relation to subsequent confirmation of preeclampsia (detection and false-positive rates, and predictive value) and the probability of diagnosis within a fixed time period (rule-in and rule-out).

Results: 600 women were enrolled in the study and follow-up information was available on 538, of whom 95 had preeclampsia at delivery and 443 did not. At enrolment the detection rate was 18 % and the false-positive rate 3.2 %; positive predictive value - probability of positive result being associated with preeclampsia - was 55 % and negative predictive value - probability of negative result not being preeclampsia - was 85 %. A positive test ruled-in delivery with preeclampsia within 28 days among 35 % and ruled-out preeclampsia with 7 days among 98 %. Repeat testing after enrolment yielded similar results to the initial sample.

Conclusion: The test has screening potential although published studies differ in the observed detection rate. Using the test to rule-out preeclampsia within 7 days can provide a significant management advantage especially for triaging patients and selecting those who can be managed at the peripheral centres.