New Point-of Care Paper Test May Improve Diagnosis of Preeclampsia

The Congo Red Dot (CRD) Paper Test is a simple, rapid, non-invasive tool that that may improve triage and the accuracy of preeclampsia (PE) diagnosis at the point of care, according to a pilot study published in E-Clinical Medicine. Further, the CRD Paper Test outperforms previously proposed serum and urine markers for PE. The authors say adoption of the CRD Paper Test as a triage tool could not only improve diagnosis, but could avoid unnecessary pre-term deliveries.

“It is not only inexpensive, easy to use, highly accepted by the nursing staff, but identifies women with PE within 3 minutes,” write the authors led by Kara Rood, from Ohio State University in Columbus. “If the CRD Paper Test results were available to obstetrical providers, a negative CRD Paper Test could improve wait times in obstetrical triage areas, avoid unnecessary admissions and lower the associated health care expenses.”

PE is typically diagnosed by hypertension and protein in the urine. However, its diagnosis is complicated by presentation of other nonspecific symptoms, including headache. Yet, PE is responsible for a significant proportion of prenatal and pregnancy-related maternal mortality and morbidity worldwide. Delays in diagnosis exacerbate these serious complications. Previous research showed that proteins in the urine of PE patients bind to Congo Red dye (urine congophilia).

In the present study, researchers designed, developed, and validated a simple point-of-care, paper-based urine test kit. Test performance was evaluated for rapid triage and diagnosis of PE among 346 consecutive pregnant women evaluated for PE in the labor and delivery triage unit of a tertiary medical center (July 2014 to July 2015). CRD Paper Test results were compared to an expert adjudicated diagnosis in each case, as well as to urine and serum analytes (placental growth factor and soluble fms-like tyrosine kinase-1), previously proposed as diagnostic aids for PE.

The researchers found that during the first triage visit just under one-third of all women received a clinical diagnosis of PE; yet, 63 percent of all women were admitted for an in-patient diagnostic work-up or delivery. The CRD Paper Test was positive in one-fourth of all participants (n = 86). Expert-confirmed diagnosis was made in PE in 96 cases. Urine congophilia was detected in 14 patients (12 percent) admitted with an uncertain diagnosis and in only 59 patients (58 percent) admitted with a diagnosis of PE. Among patients discharged home without a PE diagnosis, there were nine positive congophilia tests (8 percent), while the CRD Paper Test was positive in four patients discharged with a diagnosis of PE (36 percent).

The CRD Paper Test outperformed serum and urine markers with performance of 80.2 percent sensitivity, 89.2 percent specificity, 92.1 percent negative predictive value, and 86.7 percent accuracy. The CRD Paper Test had a positive post-test probability of 74 percent and a negative post-test probability of 8 percent, meaning one in 1.44 patients with a positive test has PE, while one in 1.1 patients with a negative test does not have PE.

“The operational simplicity of the CRD Paper Test fulfills the current needs for a diagnostic tool to aid in the rapid assessment and triage of women with uncertain PE diagnosis,” writes Rood and colleagues, two of whom have financial ties to GestVision Inc., which holds the license for the CRD test developed by the authors. “The CRD Paper Test adds clarity to help differentiate PE from PE imitators, which should result in fewer iatrogenic preterm deliveries.”

Takeaway: The CRD Paper Test is a simple, rapid, non-invasive tool that that holds potential to the accuracy of PE diagnosis at the point of care.


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