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Kidney Week

Abstract: PO0507

Dipstick Urinalysis Can Identify Patients with Early CKD Who Lack a Quantified Proteinuria Measurement

Session Information

Category: CKD (Non-Dialysis)

  • 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

  • McAdams, Meredith, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
  • Willett, Duwayne L., University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
  • Liu, Yu-Lun, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
  • Kannan, Vaishnavi, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
  • Gregg, L Parker, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
  • Hedayati, Susan, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States
Background

Urine protein-to-creatinine ratio (UPCR)>0.15 g/g or albumin-to-creatinine ratio (UACR)>30 mg/g is the gold standard for identifying patients with stages 1-2 CKD with eGFR>60 mL/min/1.73m2, but are not routinely obtained. Dipstick urinalysis semi-quantitative protein (DSP) is widely available and commonly measured.

Methods

To develop a pragmatic EHR tool to identify patients with stages 1-2 CKD, we investigated diagnostic utility of various DSP cutoffs (negative/trace, 30, 100, 300, or ≥500 mg/dL) against gold-standard proteinuria (UPCR>0.15 g/g or UACR>30 mg/g) using logistic regression. We also investigated whether addition of SG improved the diagnostic utility of DSP by comparing areas under the receiver-operating characteristic curves (AUC) for DSP with and without addition of SG. DSP was obtained from the EHR in 3,897 individuals with UPCR or UACR measured on the same date. A development model was created in a random sample of 2,728 (70%) using a bootstrap method and validated in the remaining 1,169 individuals.

Results

Mean age was 57.6±16.9 years, 51.7% were female, 25.6% Black, and 42.8% had an eGFR≤60 mL/min/1.73m2. Gold-standard proteinuria was present in 1,775 (45.5%). DSP cutoff=30 had specificity 81.1 (95% CI 79.0, 83.1), +LR=2.43 (95% CI 2.15, 2.75), -LR=0.67 (95% CI 0.63, 0.71). The combination of DSP and SG, taken continuously, performed better than DSP alone (Figure A). When including SG, a DSP cutoff of 30 had the best diagnostic accuracy vs. other cutoffs (Figure B). In the validation cohort, addition of SG to DSP also yielded a higher AUC than DSP alone, P=0.03. For DSP ≥30 as a screening test, an SG of at least ≥1.025 is needed. A more dilute urine, with a SG of 1.020, would be allowed if DSP ≥100. A DSP cutoff of 30 had an AUC of 0.652 (0.621, 0.684), P<0.001, vs. a cutoff of 300 or 500. Using DSP≥30 identified an additional 141 individuals with CKD than use of eGFR<60 alone.

Conclusion

Combining DSP and SG from a dipstick urinalysis can identify patients with early CKD who do not have a measured UPCR or UACR.

Funding

  • NIDDK Support