Point-of-Care HbA1c—A Case for Diabetes Screening and Diagnosis

Abstract

Background: Hemoglobin A1C (A1C) is routinely used to screen, diagnose, and monitor diabetes. A1C is the desired tool to assess glycemic status as it reflects 90 days of glycemic control and does not require fasting. Point-of-care (POC) A1C offers rapid turnaround enabling direct patient engagement. POC A1C tests are indicated for monitoring, but not screening or diagnosis, due to perceived inaccuracy and imprecision. To counter this impression, we evaluated the performance of two POC A1C analyzers relative to the clinical laboratory (CL). Method: Blood from 48 subjects was collected with A1C values from 4.8-12.0% A1C. Capillary blood was analyzed on the PTS Diagnostics A1CNow®+ system and Siemens DCA Vantage® while venous blood was tested at external labs on the Tosoh G8 and Roche Cobas® c513 as CL comparators. For reference, venous blood was analyzed on the Roche Cobas Integra® 400 plus. Regression analysis was used to evaluate accuracy and paired differences to measure bias. Clinical risk was calculated using A1C category cut points of < 5.7, 5.7-6.4, and ≥ 6.5% A1C. Chi-squared test was used to assess differences between methods. Precision was performed on the POC systems using 10 replicates at approx. 4.5, 7, and 10% A1C. Results: Average paired biases were identical for the POC and CL analyzers (-0.04% A1C). Slopes were 0.97, 0.99, and 0.97 for the A1CNow+, DCA, and CL analyzers (p = 0.71) and intercepts were 0.15, 0.04, and 0.12 (p = 0.99). Regression values were 0.987, 0.996, and 0.998, respectively. Clinical risk agreement was 94% for A1CNow+, 100% for the DCA, and 98% for CL analyzers (p = 0.17). Pooled precision was 3.3% CV for A1CNow+ and 1.7% CV for DCA. Conclusion: The A1CNow+ and DCA were shown to be as accurate as the clinical lab in measuring A1C values. Risk analysis showed no statistical differences between the CL and POC analyzers in classifying diabetes. The A1CNow+ and DCA are valuable tools in evaluating the diabetic state and provide physicians with real-time information to better care for patients. Disclosure C.J. Szablowski: Employee; Self; PTS Diagnostics. E. Suscha: Employee; Self; PTS Diagnostics. K. Davis: Employee; Self; PTS Diagnostics. C.Z. Xie: Employee; Self; PTS Diagnostics. K. Moskowitz: Employee; Self; PTS Diagnostics. Stock/Shareholder; Self; PTS Diagnostics. J.H. Anderson: Employee; Self; PTS Diagnostics. Board Member; Self; GENEREX Biotechnology. A. Mechley: Consultant; Self; PTS Diagnostics.