Evaluation of a protein-to-creatinine dipstick diagnostic test for proteinuria screening in selected antenatal care clinics in three Districts in the Bono-East Region of Ghana

Maternal mortality attributed to childbirth or pregnancy-related complications persists as a significant public health challenge globally and is a striking example of inequity in health outcomes for women [1]. An estimated 94 % of these deaths occur in low- and middle-income countries, with 66 % taking place in sub-Saharan Africa [2]. Some of the leading causes of maternal mortality are hypertensive disorders of pregnancy, such as preeclampsia and eclampsia (PE/E), which can lead to seizures and other fatal complications. PE/E accounts for an estimated 16 % of maternal deaths in low-resource settings (LRS) and nearly a quarter of stillbirths and newborn deaths worldwide [3], [4], [5]. In LRS, a woman’s risk of dying from PE/E is 300 times greater than in a high-resource country [6].

Currently, assessment of blood pressure and protein in urine (proteinuria) measurements are primary clinical indicators for identifying the risk of developing PE/E in pregnant women. Elevated blood pressure and total proteinuria can be considered significant and, when combined, warrant a diagnosis of preeclampsia [7], [8], [9]. Danger signs of preeclampsia, including frontal headaches, edema, and blurred vision, may also be used to support diagnosis. Early assessment of risk can facilitate early intervention and management of the condition, prior to the development of complications that pose a risk to the health of mothers and babies. Global recommendations indicate a pregnant woman should have at least four antenatal care (ANC) visits over the course of pregnancy, with blood pressure measurement and proteinuria measurement assessed during each visit. However, some women do not attend ANC regularly or the diagnostic tools needed for these assessments are not readily available. This can lead to difficulties or delays in the detection of complications, including PE/E [10], [11].

There also are barriers to obtaining accurate proteinuria measurement with the existing tools widely available in LRS. The gold standard for measuring proteinuria is 24-hour urine collection [12], [13], [14]. However, it is inconvenient given the time and resources required and is only available in some secondary- and tertiary-level settings due to its high cost and complexity. In addition to these barriers to use, 24-hour urine collection is subject to errors, such as incomplete sample collection that renders the result inaccurate [14], [15], [16]. In LRS, protein measurement using a urine dipstick test is the most common method for proteinuria assessment due in part to its low complexity and cost [17]. However, the clinical utility of protein-only dipstick measurements is limited, and the World Health Organization considers the accuracy of these tests to be low [10]. A recent systematic review found that the accuracy of protein-only dipstick measurements ranges widely, with performance as low as 20 %–40 % sensitivity and specificity [18]. Other studies have shown negative and positive predictive values for protein-only dipsticks at 34 % and 36 %, respectively, and questioned their utility in accurately determining significant proteinuria [19]. One of the causes of poor test performance is that protein-only dipsticks cannot adjust for daily fluctuation in body hydration. This can lead to both over- and underestimation of protein measurements, depending on the level of urine dilution [20].

Due to the limitations of protein-only urine dipsticks and 24-hour urine collection, some health guidelines, such as those from the UK National Institute for Health and Care Excellence, have recommended the use of the protein-to-creatinine ratio (PrCr) or the albumin-to-creatinine ratio for detection of proteinuria [7]. When using a chemistry analyzer, the most widely reported threshold for differentiating an abnormal versus normal proteinuria result is a PrCr of greater than or equal to 0.3. Additionally, in the World Health Organization 2017 updated guidelines to Managing Complications in Pregnancy and Childbirth, a urinary PrCr of 0.3 or greater was added to the diagnostic criteria for proteinuria, alongside 24-hour urine collection, rather than replacing it [8].

The measurement of the protein and creatinine concentrations in a spot urine sample is determined and calculated in laboratory settings using chemistry analysis [17]. However, like other methods that rely on complex medical infrastructure, Brown et al. warn that “as with 24-hour urine collection, this laboratory-based testing method is similarly inaccessible in LRS due to cost, complexity, and infrastructure requirements. Further, this method also relies on effective referral networks” [21]. As such, there is a critical gap in accessible, low-cost, and accurate screening tools for proteinuria at the point of care. Specifically, point-of-care measurement of protein and creatinine concentrations can confer the benefits of both the improved accuracy of the PrCr and the easy-to-use format of a urine dipstick.

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