Different DCCT-aligned HbA1c methods and the GMS contract.
BACKGROUND
Previously, different analytical methods could be compared on statistical and clinical grounds. Since 2003, the UK Departments of Health and general practitioners agreed a new primary care contract. This contract utilises clinical targets resulting in a third way to compare analytical methods.


METHODS
We compared two DCCT-aligned HbA1c analysers (Variant II analyser and a Tosoh G7) using 161 randomly selected patient specimens to see if different methods could lead to a difference in the classification for glycaemic control.


RESULTS
Ninety-seven (60.2%) and 109 (67.7%) patient specimens had a HbA1c <or= 7.4% with the Variant II analyser and Tosoh G7 respectively, that is, the two methods differed according to the DM6 GMS target by 12 patients or 7.5% of the total number of patients in the study. When McNemar's test was performed, the difference between the two methods was statistically significant with p<0.00083.


CONCLUSIONS
The National Glycohemoglobin Standardisation Programme has used clinical limits to set standards for HbA1c based on a clinical recommendation from the American Diabetes Association and has resulted in improved generalisability of results. The difference found in this study would not have affected payment under the current GMS contract. However, if the maximum threshold for payment was increased from 50% and/or the HbA1c target was decreased from 7.4%, then payment may be affected. It is important that policy makers and healthcare professionals appreciate the limitations of DCCT alignment for HbA1c methods.
Twomey
P J
PJ
Department of Clinical Biochemistry, The Ipswich Hospital, Ipswich, Suffolk, UK. ptwomey@nhs.net
Pledger
D R
DR
D003284:Contract Services / Q000592:standards*; D006442:Glycated Hemoglobin / Q000032:analysis*; D006452:Hemoglobinometry / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D006801:Humans; D011320:Primary Health Care / Q000592:standards; D019984:Quality Indicators, Health Care; D015203:Reproducibility of Results; D006113:United Kingdom
D006442:Glycated Hemoglobin