Diabetes is a significant chronic disease that can lead to complications such as kidney disease, neuropathy, and retinopathy, making early diagnosis and proper management crucial [1-3]. In South Korea, the rising prevalence of diabetes underscores the importance of primary care in early diagnosis and management, as primary care providers play a vital role in enhancing patient quality of life and preventing complications through timely intervention [4,5]. Particularly critical is the early diagnosis and management of kidney disease, as kidney function damage is irreversible and often necessitates costly treatments like dialysis or kidney transplantation in end-stage renal disease [6,7]. The Korean Society of Nephrology (KSN) reported in 2019 that the number of end-stage renal disease patients in Korea is increasing, imposing a substantial burden on health insurance [7,8]. Early detection and management can prevent disease progression, improve patient quality of life, and reduce both the economic burden on patients and the need for high-cost treatments [9,10].

The albumin-to-creatinine ratio (ACR) test is recommended for early screening of kidney disease, regardless of whether they have diabetes or not. This test measures the ACR in urine, providing a simple, non-invasive method to detect early kidney damage [11,12]. The guidelines of the KSN recommend regular ACR testing for high-risk groups, including diabetes and hypertension patients [13,14]. This test helps detect early changes in kidney disease, allowing for timely treatment and significantly improving patient outcomes [13,15].

However, precise quantitative ACR tests are difficult to use in primary care due to high costs and the need for outsourced testing. Traditional benchtop ACR tests are costly and time-consuming, with results taking days to weeks. This delay hinders early diagnosis and prompt treatment. Therefore, there is a growing need for a more affordable and rapid method, such as a digital camera-based ACR test kit [9,11]. While these products already exist, studies have shown their effectiveness as a screening tool compared to traditional quantitative analyzers, particularly in detecting albuminuria [16]. Recent advancements in mobile health (mHealth) technology have further increased accessibility, making it easier for both patients and healthcare providers to use these tools effectively [17,18]. Building on these findings, this study specifically focuses on evaluating their applicability and effectiveness in primary care settings, providing additional data on their clinical implementation in real-world clinical environments [9,11,13].

In response to this need, we conducted a study to compare the clinical efficacy of the digital camera-based ACR test kit with the traditional benchtop equipment used in hospitals. Specifically, we compared the clinical performance of the mobile digital camera-based QSTAG QSCheck-UISACR ACR test kit with traditional benchtop devices. The study aimed to evaluate the accuracy and reliability of the two digital camera-based ACR test kits compared to conventional benchtop ACR test equipment. By applying both testing methods in various clinical settings and comparing the results, we sought to demonstrate the efficiency of the digital camera-based kits in the early detection of kidney damage through measurements of albumin and creatinine levels and ratios.

Table 3, 4 presents the results of a comparative analysis between the QSCheck-App and a comparator benchtop device across three key biomarkers: microalbumin, creatinine, and the ACR.

This study evaluated the efficacy of a novel device designed to detect and monitor albuminuria in non-hospital settings or primary care institutions without benchtop equipment. When compared to the benchtop machines in tertiary care hospitals, the device showed a concordance rate of 78.5%, despite the need for adjustments due to differences in experimental conditions. By expanding the recognition range based on differences in albuminuria in semi-quantitative tests, the concordance rate increased to 96.0%.

Albuminuria serves as both a marker for diagnosing and tracking the progression of kidney disease and an independent risk factor for cardiovascular disease [11,19]. Microalbuminuria, defined as 30–300 mg/day corresponding to 1+~2+ on semi-quantitative urine tests, is an early predictor of kidney disease and indicating potential progression even when renal function appears normal [20,21]. For patients with diabetes or hypertension, proteinuria can develop as the disease progresses. Typically, diabetic patients are tested every 6 months or annually, while hypertensive patients are not routinely tested. The significance of this device lies in its ability to be used regularly without burden, allowing for the early detection of proteinuria. Rather than focusing on absolute values, this device is valuable for tracking serial changes, enabling patients to visit healthcare providers early if proteinuria reaches a significant level, thus facilitating early evaluation for kidney disease. This early detection is crucial for increasing disease awareness and preventing or delaying disease progression through self-management. Studies in Japan have shown that in patients without diabetes, those with albuminuria had a proportional increase in the need for dialysis over 17 years of follow-up based on dipstick levels. Another study indicated that the progression of kidney function deterioration in newly diagnosed chronic kidney disease patients was proportional to the level of albuminuria [15,21].

The progression of albuminuria leading to decreased renal function is well-documented. Initially, glomerular hyperfiltration increases glomerular filtration rates, which later decline [22]. However, early diagnosis and treatment of albuminuria can improve outcomes for kidney disease and cardiovascular disease [13,19].

Traditional methods for measuring albuminuria below 300 mg/day are often insufficiently sensitive, necessitating various antibody-based methods (RIA, nephelometry, immunoturbidimetry, ELISA) to detect lower levels of albuminuria. Recently, HPLC methods have enable the detection of both immunoreactive and immunounreactive albumin, allowing for more comprehensive screening [12,14]. However, these techniques rely on expensive equipment, limiting their use in primary care settings.

The method used in this study involves a digital camera to analyze traditional urine test strips, overcoming the limitations of visual qualitative tests and providing a more cost-effective screening method. Originally developed for controlled environments with specific digital cameras, advances in digital camera technology and analysis software have enabled the use of widely accessible digital cameras for immediate analysis of urine chemistry strips. This development is part of the broader field of digital healthcare, which shows promise for high accessibility and diverse applications.

The strength of this study lies in its evaluation of the clinical utility of in vitro diagnostic devices within digital healthcare, conducted as a multi-center study to assess the device’s efficacy in various environments. The study validated the screening test’s significance by demonstrating equivalence to benchtop equipment used in hospitals.

However, there are limitations. The study did not match subjects for underlying diseases, age, or gender, and it assessed the device based on a single experiment despite controlling for other potential influences. Furthermore, the recruitment process for study participants needs to be more systematic to strengthen the accuracy of the research. Although the study compared certified medical devices, the performance differences among benchtop equipment suggest a need for equivalence evaluations with precision quantitative analyzers widely used in hospitals [23-25]. Additionally, to enhance applicability, usability assessments with diverse users and evaluations in primary care settings are necessary to address convenience. While this study assessed the clinical utility of in vitro diagnostic devices, further research is needed to improve user convenience and accuracy. Well-planned studies should validate the device’s efficacy and establish the semi-quantitative test’s performance relative to precision quantitative analyzers used in existing hospital diagnostic systems.

In conclusion, this study confirmed that the digital camera-based ACR test kit has high accuracy and concordance compared to the benchtop device used in hospitals. QSCheck-UISACR proves to be a useful tool for the early diagnosis and management of kidney disease, particularly in primary care settings. The findings suggest that this mobile diagnostic tool can improve patient accessibility and potentially reduce healthcare costs.