Prospective evaluation of accuracy, precision, and reproducibility of an at-home hemoglobin A1c sampling kit.

BACKGROUND

The measurement of hemoglobin A1c (HbA1c) is critical to the optimal therapeutic management of diabetes. To be most useful, the HbA1c value should be available at the clinical visit. Recently, a number of at-home sampling kits have been developed that facilitate the timely availability of HbA1c results. This is a report of the accuracy, precision (among-subject), and reproducibility (within-subject) of one such kit, B-D A1c, At-Home-Test, which combines a filter paper technique for spotting capillary blood with an immunoturbidometric assay (a variation of the Cobas Integra Hemoglobin A1c method also referred to as Roche Unimate).

METHODS

The B-D A1c At-Home test kit was evaluated in a clinical trial using 1625 dried blood spot samples from 59 subjects diagnosed with type 1 or type 2 diabetes collected in an in-clinic setting. Data for replicate samples were compared against those from the standard Cobas Integra Hemoglobin A1c assay and from the BioRad Variant high-performance liquid chromatography [HPLC] assay. The effects of subjecting the dried spotted blood samples to prolonged elevated temperatures was evaluated in a separate laboratory analysis.

RESULTS

The B-D A1c At-Home results, which are highly correlated with the standard Cobas Integra Hemoglobin A1c assay, (r2 = 94.7%), demonstrate excellent within-subject reproducibility for 3- to 10-day-old samples (coefficient of variation = 2.7%), and provide a coefficient of variation for among-subjects that is 3.9%. There were no clinically significant differences (i.e., < 0.3 units) in samples aged 3 to 10 days, between venous or capillary blood samples, or from freezing and thawing or prolonged exposure of B-D A1c At-Home dried blood samples to elevated temperatures before assay.

CONCLUSIONS

The B-D A1c At-Home kit combines the accuracy, precision, and reproducibility of a clinical laboratory test with the convenience of at-home sample collection. This product may add to the convenience of both patient and health care provider by making it easier for patients to obtain their HbA1c values and have them available at their visit to the clinician.