#709 Limitations of urine dipstick testing in early diagnosis of diabetic kidney disease (DKD) and the necessity of measuring urinary albumin-to-creatinine ratio (UACR)

Abstract Background and Aims Diabetic Kidney Disease (DKD), the leading cause of end-stage renal disease (ESRD) worldwide, must be diagnosed early to allow for timely intervention and prevention of severe progression. Chronic kidney disease (CKD) can be easily diagnosed and its severity determined by estimated glomerular filtration rate (eGFR) and urine protein-creatinine ratio (UPCR) or urine albumin-creatinine ratio (UACR). However, recent studies suggest that efforts to achieve early diagnosis of CKD have been insufficient. We evaluated the accuracy of urine dipstick testing in the early diagnosis of DKD and confirmed the importance of UACR measurement. Method Data were used from 1,323 diabetes education inpatients at our hospital. Results from simultaneous urine dipstick testing and UACR measurement upon admission were analyzed. Results of urine dipstick testing were classified into five levels (−, ±, 1+, 2+, 3+), and results of UACR were categorized into three groups: normoalbuminuria (UACR < 30 mg/gCr), microalbuminuria (30 ≤ UACR < 300 mg/gCr), and macroalbuminuria (UACR ≥ 300 mg/gCr). Urine dipstick testing was considered positive with a result of 1+ or higher, and microalbuminuria or greater was defined as DKD. The accuracy of urine dipstick testing in diagnosing DKD was then evaluated. Results Of the 1,323 cases, there were 202 true positives, 262 false negatives, 13 false positives, and 846 true negatives (Table 1). When diagnosing DKD with urine dipstick testing 1+ or higher, the prevalence was 35.1%, the positive and negative rate was 16.3% and 83.7%, the accuracy was 79.2%, the sensitivity was 43.5%, the specificity was 98.5%, the positive and negative predictive value was 93.9% and 76.3% (Table 1). In addition, when the cut-off for a positive result in urine dipstick testing was set to ± or higher, there were 314 true positives, 150 false negatives, 108 false positives, and 751 true negatives. The prevalence was 35.1%, the positive and negative rate was 31.9% and 68.1%, the accuracy was 80.5%, the sensitivity was 67.7%, the specificity was 87.4%, the positive and negative predictive value was 74.4% and 83.4% (Table 2). Conclusion Urine dipstick testing demonstrated low sensitivity (43.5%) for early DKD diagnosis, with a high risk of misdiagnosing 66.5% of patients with microalbuminuria or higher as normoalbuminuria. Even with a cutoff value adjusted to ± to improve sensitivity, the sensitivity was limited to 67.7%, leaving 32.3% of early cases undetected. These findings highlight the limitations of dipstick testing for early detection of DKD. Regular UACR measurements are essential, as emphasized in the 2024 clinical practice guidebook for the diagnosis and treatment of CKD published by the Japanese Society of Nephrology, to enable early detection and timely intervention in DKD.