Volumetric absorptive microsampling at home as an alternative tool for the monitoring of HbA1c in diabetes patients

Microsampling techniques have several advantages over traditional blood collection. Dried blood spot (DBS) sampling and blood collection with heparinized capillaries are the standard techniques. Volumetric absorptive microsampling (VAMS) is a novel technique that collects a fixed volume of blood by applying an absorbent tip to a blood drop. In the present study we explored the feasibility of HbA1c monitoring with VAMS sampling at home and analysis in the laboratory. Diabetic patients were enrolled in this study during consultation with the endocrinologist. A venous (adults) or capillary (children) sample was taken for immediate HbA1c analysis. DBS (n=1) and dried VAMS (n=2) were collected at home and sent to the laboratory. For 25 pediatric patients one VAMS was collected during consultation for immediate analysis (without drying), referred to as "wet VAMS". HbA1c analyses were performed on a Tosoh HLC-723 G8 high-performance liquid chromatography (HPLC) analyzer. The median time between sampling at home and analysis was 3 days. Results of HbA1c in dried VAMS showed a poor agreement with venous/capillary blood collected in hospital (concordance correlation coefficient CCC=0.72). Similar observations were found with standard DBS. An excellent agreement was obtained between HbA1c results on wet VAMS (CCC=0.996) and standard blood samples. Patients experienced VAMS and DBS as easy and convenient to use. Utilizing equipment standard available in the clinical laboratory, the use of home-sampled dried VAMS and DBS is not a reliable tool for the monitoring of HbA1c. However, perfect agreement between HbA1c measured on wet VAMS and capillary microsamples was obtained.