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Paper-Based Test Being Developed to Improve Preeclampsia Diagnosis and for Decentralized Settings


NEW YORK – A group of researchers at the University of Illinois at Chicago has developed an ink and paper-based test for preeclampsia that could offer a more accurate and objective method for diagnosing the condition.

Because the test can be used in a decentralized setting, it may also provide a tool for preeclampsia diagnosis in low- and middle-income countries without the need for laboratory facilities. 

Preeclampsia is primarily diagnosed by looking at a combination of indicators, including blood pressure, weight, and urine protein tests for kidney disease, but predicting and diagnosing the disorder is still difficult and can be inaccurate, as those factors often crop up in other diseases. A variety of diagnostic companies and researchers have developed tests specifically for the condition, including PerkinElmer, Progenity, and Swiss firm Momm Diagnostics, but widespread adoption still lags.

To address this, Irina Buhimschi, a professor of obstetrics and gynecology and director of the perinatal research laboratory at UIC, and her husband set about developing a simple, easy-to-use test while she worked at Yale University. 

In previous proteomics research, she and her team made a connection between the development of preeclampsia — pregnancy-related hypertension that can cause preterm birth and stillbirth and result in kidney and liver failure — and urinary misfolded proteins. 

The researchers later discovered that those misfolded proteins are congophilic, meaning they bind to Congo red, a specific type of dye. Drawing on these discoveries, other groups of researchers from Israel, India, and the UK validated the clinical utility of determining congophilia in pregnant women to diagnose preeclampsia.

Buhimschi's team, meanwhile, used its knowledge to develop a preliminary rapid diagnostic test kit, the CR Dot (CRD) Paper Test, a paper-based test that uses the dye to detect the presence of misfolded proteins in a pregnant patient's urine. To run the test, the urine sample is mixed with the dye and then pipetted onto reaction papers. If the congophilic proteins are present in the urine, the sample will migrate across the paper, since the proteins cannot bind to the nitrocellulose once they've already bound to the dye. If the proteins aren't present, the mixture will stay at the point of application, Buhimschi said. 

Their test was validated in a prospective study published in eClinicalMedicine in 2019 that evaluated the test in 346 women in the labor and delivery triage unit at the Ohio State University Wexner Medical Center. That study found the test had 80 percent sensitivity, 89 percent specificity, 92 percent negative predictive value, and 87 percent accuracy to correctly diagnose preeclampsia. 

The preliminary version of the test has undergone several other validation studies, Buhimschi said. Another key study is soon to begin in Africa and will take place over the next nine months in Uganda and Ethiopia. Currently, the researchers are waiting on ethics approvals from the Uganda National Council for Science and Technology and other organizations in Ethiopia, Buhimschi said.

The study, which is being funded by global health nonprofit Grand Challenges Canada, will test 3,500 women in 21 clinics across the two countries, she added. Those clinics embody three different types of healthcare settings: primary care, secondary hospitals, and tertiary care centers for patients who need acute care. The goal of working within those settings is to identify women who get lost in the shuffle and never receive a diagnosis, or receive the diagnosis too late to make it to a hospital sufficiently equipped to deal with the condition, she said. The researchers also think that there may be women and providers who don't recognize the signs of preeclampsia or downplay them, affecting their treatment, she said.

Ethiopia and Uganda were chosen for the study because they have high instances of both preeclampsia and mortality as a result of the disease, Buhimschi said. The researchers wanted to conduct studies of the test where under-diagnosis is a problem and where there are fewer resources and no alternative diagnostic tests for the disorder.

In addition, UIC and other partners were already conducting ongoing studies in those countries to assess the availability of resources for pregnant women, so the researchers will "have knowledge of what's available" to women, she said. The study will be able to look at how clinicians use the test once it's available, which could set the stage for professional organizations in the region to establish guidelines for how diagnostic tests such as CRD are to be implemented in particular settings.

"How things are done in the West aren't transferrable to LMICs," Buhimschi said, as pregnant women in the US have access to centralized laboratories and ultrasounds, whereas women in low-income countries may not. 

Beyond just measuring the feasibility and clinical utility of the test, ancillary studies will also be conducted to measure health literacy and provider attitudes toward using diagnostic tests like the one Buhimschi and her colleagues are developing. The studies will also help inform an appropriate and sustainable price point for the test in LMICs, according to Buhimschi. While the researchers have made calculations for potential price points, she said that they have to first establish whether there is clinical utility for the test at lower levels of care in the first place. "We'd like to make it affordable for the people who need it," she said.

Steps toward commercialization

Although Buhimschi currently works at UIC, and UIC is running the African study, Yale holds the patents for the test and is in charge of its licensing. The university has licensed patents related to the test to two different companies: GestVision and Shuwen Biotech. GestVision holds the rights to commercialize the test in the US, while Shuwen has the rights to the test in China. Both companies also hold various rights to the intellectual property in countries outside the US and China, respectively. 

Both companies have developed their own versions of the test using the underlying concept Buhimschi and her team spearheaded. According to Wendy Davis, CEO of GestVision, the company knew there was a need for better preeclampsia diagnosis in the US and went looking for a test that could help meet that demand. The disease "is still very challenging to diagnose," she said, and we "still don't have it under control." 

She noted that the paper test developed by Buhimschi's team was challenging to read and interpret for a lay user, so GestVision set to work on developing it further, using reproducible materials that could be mass produced while reducing the amount of sample handling required. GestVision's version of the test is configured "like a pregnancy test," she said, and doesn't take a "sophisticated laboratorian" to perform. It's "very similar" to the original test, in that the sample is added to a test strip that picks up the dye. The result is also returned in three minutes via a display window. 

GestVision is currently in the regulatory stage of the test's commercialization plan, Davis said, and is hoping to get clearance from the US Food and Drug Administration — likely de novo clearance — relatively soon, with plans to launch "ASAP" once that approval has been received. She added that the company has explored reimbursement options and believes payors will be willing to reimburse the test, although the price hasn't been determined yet. Davis said that the test "will not be expensive."

Davis said she sees the test being used initially at the point of assessment for preeclampsia, most often the hospital where the rest of a prenatal workup is performed. But as more proof of applicability becomes available, the use case of the test could evolve to doctors' offices or at the bedside. 

GestVision is donating its version of the test to be used in Buhimschi's African study, as it is "synergistic" with the studies GestVision is conducting in the US, Buhimschi noted.

Meantime, Shuwen Biotech has already commercialized its version of the test in China, its CEO, Jay Zhang, said in an interview. The firm licensed the foundational patent that is based on the correlation between the proteins and preeclampsia, he said, and developed its own qualitative test, CapCord, that uses Congo red staining, as well. 

Zhang declined to disclose details of how the test worked due to competitive concerns but said that while the principle of the test is the same as Buhimschi's, the method is different, and it is not a lateral flow test. In previous statements, Shuwen has said the three-minute test doesn't require specialized instrumentation and is more than 95 percent accurate in diagnosing women with preeclampsia admitted to hospitals. According to a 2020 paper published in PLOS One, the point-of-care device uses a capillary tube-based slow release method to transfer a mixture of Congo red and urine into a cellulose membrane compartment, where the result can be detected.

Shuwen has already received approval to market the test in China and has partnered with PerkinElmer to commercialize the test in a variety of regions, including India and South America, Zhang said. The firm announced its partnership with PerkinElmer in early 2020 and began selling the kits in China at the end of 2020, although its uptake has been limited by "a lot of hurdles," he said, including the need for expert consensus on the validity and utility of the test and the need for government pricing of the assay. Any novel biomarker has to go through the price setting process "province by province" to be used in public hospitals, Zhang said, a process that can be lengthy and complex. 

Despite those obstacles, the test is "getting more widespread" in China and is being used to aid in diagnosis. In an ideal world, the test would be used for screening and prognosis, but the company still needs to generate more data for different uses, he said, adding Shuwen is working to develop a quantitative version of the test.

The cost of the test varies depending on the country it's being sold in, Zhang said, but in developing countries it costs less than $20. 

Buhimschi emphasized the importance of using the test in LMICs for "people who need it the most" and where it will "make an impact."