Accuracy of Three Commercial Home-Use Hemoglobin A1c Tests.

Background: The COVID-19 pandemic and the rapid expansion of telemedicine have increased the need for accurate and reliable capillary hemoglobin A1c (HbA1c) testing. Nevertheless, validation studies of commercially available products suitable for home use have been in short supply. Methods: Three commercial home-use capillary blood sample HbA1c tests (Home Access, CoreMedica, and A1cNow+) were evaluated in 219 participants with type 1 or type 2 diabetes (4-80 years years of age, HbA1c 5.1%-13.4% [32-123 mmol/mol]) at four clinical sites. Comparisons were made between HbA1c measurements from the commercial tests and paired venous samples for which HbA1c was measured at two central reference laboratories. The primary outcome was percentage of commercial HbA1c values within 5% of the corresponding reference values. Results: HbA1c values were within 5% (relative difference) of paired reference values for 82% of Home Access samples, 29% of CoreMedica samples, and 46% of A1cNow+ samples. Absolute differences were within 0.3% of the reference value for 75% of Home Access samples, 28% of CoreMedica samples, and 44% of A1cNow+ samples and exceeded 0.5% for 8%, 55%, and 37%, respectively. Conclusions: None of the commercial home-use HbA1c tests produced the National Glycohemoglobin Standardization Program goal of ≥90% measurements within 5% of a DCCT venous reference. However, the Home Access product performed substantially better than the CoreMedica or A1cNow+ products. Telemedicine is likely to persist as a mainstay of diabetes care well after the COVID-19 era. As such, accurate home-based HbA1c assessment represents an urgent need for the diabetes community.

Performance of an Advanced Interferon-Gamma Release Assay for Mycobacterium tuberculosis Detection.

BACKGROUND: The LIAISON® QuantiFERON®-TB Gold Plus (QFT-Plus) assay, a fully automated chemiluminescence immunoassay (CLIA) system, has recently received FDA approval for the detection of interferon-γ (IFN-γ) on the LIAISON XL analyzer. Here, we evaluated the diagnostic performance of the LIAISON's CLIA method in comparison to the widely used ELISA method using the Qiagen QuantiFERON-TB Gold Plus Blood Collection Tubes. METHODS: Heparinized blood samples from 329 participants were categorized into 3 cohorts, including 15 with confirmed tuberculosis (TB) (active TB cohort), 129 non-TB (low-risk cohort), and 185 potential TB (mixed risk cohort). Samples were analyzed with both assays and results were interpreted according to the manufacturers' criteria. RESULTS: The LIAISON CLIA assay showed an overall agreement with the Qiagen ELISA assay in 13/14 (92.8%) samples among the active cohort, 93/95 (97.9%) among the low-risk cohort, with a Cohen's kappa value of 0.76 and 0.74, respectively. Test results for 185 mixed risk cohort participants showed 97.8% agreement between the LIAISON and the Qiagen, with 17 positive, 163 negative, and 1 indeterminate. Four samples were discrepant; 3 of these were negative on the ELISA but positive on the CLIA assay. CONCLUSION: Overall, the results were comparable (>92% agreement) in our study cohorts. In addition, our mixed risk cohort results showed an excellent agreement of 0.88 (Cohen's kappa value) between the 2 assays. These findings suggest that the automated LIAISON QFT-Plus assay has a comparable diagnostic performance to the Qiagen assay and can be used for latent TB infection (LTBI) diagnosis.

An Evaluation of Two Capillary Sample Collection Kits for Laboratory Measurement of HbA1c.

Background: The COVID-19 pandemic has impacted the conduct of clinic visits. We conducted a study to evaluate two academic laboratories' fingerstick capillary blood collection kits suitable for home use for laboratory measurement of HbA1c. Methods: Four clinical sites recruited 240 participants (aged 4-80 years, HbA1c 5.1%-13.5%). Capillary blood samples were obtained by the participant or parent using collection kits from two laboratories (University of Minnesota Advanced Research and Diagnostic Laboratory (ARDL) and Children's Mercy Hospital Laboratory (CMH)) and mailed under varying shipping conditions by United States Postal Service to the laboratories. Comparisons were made between HbA1c measurements from capillary samples and contemporaneously obtained venous samples. The primary outcome was percentage of capillary HbA1c values within 5% of the corresponding venous values. Results: HbA1c values were within 5% of venous values for 96% of ARDL kit specimens shipped with a cold pack and 98% without a cold pack and 99% and 99%, respectively, for the CMH kits. R2 values were 0.98, 0.99, 0.99, and 0.99, respectively. Results appeared similar across HbA1c levels and for pediatric and adult participants. Usability survey scores were high. Conclusions: Capillary blood collection kits, suitable for home use, from two academic laboratories, were demonstrated to be easy to use and provided results that are comparable with those obtained from venous specimens. Based on these results, there is strong evidence that HbA1c measurements from capillary specimens obtained with these specific kits can be used interchangeably with HbA1c measurements from venous specimens for clinical research and clinical care.