Researchers at The John Curtin School of Medical Research at The Australian National University (ANU) in 2014 conducted a comparative study of HbA1c (glycated haemoglobin) levels in dried blood spots (DBS) versus venous whole blood. The results of this work have been published in the peer reviewed journal BMC Clinical Pathology.
The use of dried blood spot sampling for the measurement of HbA1c: a cross-sectional study
Authors: Mastronardi, Claudio; Whittle, Belinda; Tunningley, Robert; Neeman, Teresa; Paz-Filho, Gilberto.
BMC Clinical Pathology (2015), 15:13
This work was also accepted at the 2015 ADS/ADEA Annual Scientific Meeting where a poster was presented. The poster can be viewed here:
Time-dependent effects of HbA1c levels measured through dried blood spot sampling.
Authors: Paz-Filho, Gilberto; Mastronardi, Claudio; Neeman, Teresa; Tunningley, Robert; Whittle, Belinda,
2015 ADS/ADEA Annual Scientific Meeting, 26-28 August 2015, Adelaide.
In total 115 volunteers were sampled, including 67 people with previous diagnosis of diabetes (11 Type 1 and 56 Type 2) and results were compared between samples on days 0, 4, and 7 after collection. The results are illustrated below.
Figure 1. There is an excellent correlation in HbA1c levels in capillary dried blood spot (DBS) samples and venous whole blood (WB) samples. This graphs display linear regression of corrected HbA1c levels on Day 4 and 7 after initial sampling using the MyHealthTest dried blood spot collection kits and venous whole blood samples analysed on Day 0. There are high levels of correlation (R2 > 0.90 for all days).
The median coefficients of variation of the dried blood spot samples was less than 2.3% for all days, demonstrating the precision of capillary dried blood spot testing for HbA1c. At less than 3% this level is comparable or superior to conventional laboratory variation in whole blood HbA1c testing and superior to many of point of care (POC) HbA1c testing units.
Mean and standard deviations of HbA1c levels in whole blood and dried blood spots were calculated and no significant difference between the two groups was detected.
Table 1. Mean, standard deviation and intra-assay coefficient of variation for venous whole blood (WB) on Day 0 and dried blood spot (DBS) on Day 0,4 and 7.
Bland Altman analysis is used to measure the difference between two assays. The test for days 4 and 7 revealed a bias approaching zero with limits of agreement less than 1.
Figure 2. Bland-Altman chart of dried blood spot versus whole blood samples on Day 4 post-sampling.
Study participants were asked to collect their own dried blood sample samples using the MyHealthTest DBS collection kit, and had venous samples collected by an experienced phlebotomist. They then rated their experience as illustrated in Figure 3. The convenience of at home sample collection combined with a preference of finger prick sampling over traditional venous sampling can improve patient compliance to HbA1c testing.
Figure 3. 89% surveyed rated finger prick blood sampling with the MyHealthTest kit as good, very good or excellent. 59% expressed a preference for finger prick sampling over traditional venepuncture.
More detail can be seen in the MyHealthTest HbA1c Dried Blood Spot Test Technical Monograph.
Results from the first cohort of volunteers (34 people) were presented at the 2014 ADMA meeting. The poster can be viewed here:
Measurement of Glycated Haemoglobin A1c (HbA1c) in Dried Blood Spot Samples: An Alternative to Traditional Venous Blood Sampling.
Authors: Whittle, Belinda; Mastronardi, Claudio; Tunningley, Robert; Paz-Filho, Gilberto
2014 ADMA meeting, September 2014, Melbourne.
Ongoing comparative studies continue.
Testing has shown that after holding dried blood spot samples at 46 degrees C for 2 days there was a slight increase in the HbA1c level from people with an HbA1c of 7.5% and higher. Therefore, there may be a small variation in results if samples are subjected to extreme temperature conditions.
Glycated haemoglobin or HbA1c is commonly measured in the management of diabetes. The test has more recently been endorsed as a diagnostic test for Type 2 diabetes by WHO, the International Diabetes Federation and by an Australian Diabetes Society expert committee. These recommendations have been outlined in an article in the Medical Journal of Australia in 2012
HbA1c has now been approved for reimbursement for the diagnosis of diabetes in Australia.
Dried blood spot (DBS) testing was first introduced into the literature in 1963 by Guthrie and Susi and is now routinely used in heel-prick sampling of newborn infants. There is now a wide body of literature describing the use of DBS for measuring a range of analytes.
DBS sampling for HbA1c collection is well established. A few of these articles include: