Implications of different DCCT-aligned HbA1c methods on GMS clinical indicators.
BACKGROUND
In 2003, a new General Medical Services (GMS) contract was agreed between UK general practitioners and the Department of Health. The three diabetes codes DM5-DM7 require glycated haemoglobin (HbA(1c)) testing and comprise 30 points in total, with 27 points being related to target glycaemic control. We compared two routinely used Diabetes Control and Complications Trial (DCCT)-aligned HbA(1c) methods to determine if different HbA(1c) methods could lead to postcode treatment to target across the UK.


METHODS
A total of 164 specimens were randomly selected from diabetic patients attending the Diabetes Centre at the Ipswich Hospital. Samples were analysed on both a DCA 2000+ Analyser and a Variant II analyser.


RESULTS
Despite a mean difference of only 6.5% between the two methods, 32 (19.5%) and 63 (38.4%) patient samples had an HbA(1c) < or = 7.4% with the Variant II analyser and DCA 2000+ Analyser, respectively. Thus, the two methods differed according to the DM6 GMS target by 31 patients, or 18.9% of the total number of patients in this study. The difference between the two methods was statistically significant with P < 10(-09) (McNemar's test).


CONCLUSIONS
DCCT-alignment has improved the transferability of HbA(1c) values; however, it is not perfect. It is important that the limitations of current DCCT-aligned HbA(1c) methods are understood by health-care professionals and policy makers, as these may have important financial and clinical implications.
Twomey
P J
PJ
Department of Clinical Biochemistry, The Ipswich Hospital, Ipswich, UK. ptwomey@nhs.net
Rayman
G
G
Pledger
D R
DR
D019411:Clinical Laboratory Techniques / Q000592:standards*; D003920:Diabetes Mellitus / Q000175:diagnosis*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D012015:Reference Standards
D006442:Glycated Hemoglobin