Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2014) 35 P364 | DOI: 10.1530/endoabs.35.P364

ECE2014 Poster Presentations Diabetes (epidemiology, pathophysiology) (63 abstracts)

Does systematic error in the HbA1c measurement matter when locally analyzed HbA1c is used for benchmarking in a national diabetes register?

Siri Carlsen 1 , John Cooper 1, , Geir Thue 2 , Thomas Røraas 2 , Karianne Løvås 2 , Lasse Gøransson 1 & Sverre Sandberg 2


1Stavanger University Hospital, Stavanger, Norway; 2University of Bergen, Bergen, Norway.


Introduction: HbA1c is an important quality indicator when benchmarking diabetes clinics. Systematic error in the measurement of HbA1c could result in inappropriately high or low values, and if not corrected give a wrong impression of the standard of care.

Methods: We included data on HbA1c from the Norwegian adult diabetes register on 3,854 type 1 diabetics attending 13 hospital clinics. Correction factors for HbA1c were derived from the results of the local laboratories’ quarterly external quality assessment scheme. These factors were used to correct the patient yearly median HbA1c before the corrected clinic median HbA1c was calculated

Results: Before correcting the clinic median HbA1c, values varied from 7.7 to 8.6%, and after correcting from 7.8 to 8.2%. Compared to the uncorrected values, the corrected values were within ±0.2% for all but one clinic whose median HbA1c was reduced with 0.4%. After correction the overall percentage of type 1 diabetics with poor glycemic control (HbA1c>9.0%) was reduced from 23.9 to 21.0%. One clinic reduced the percentage with 11% and two clinics with 5% whereas to clinics increased the percentage of patients with poor glycemic control with 5% after correction.

Conclusion: For six out of 13 clinics, correcting HbA1c values changed the percentage of patients with poor glycemic control, and one clinic reduced its median HbA1c substantially. Our results suggest that knowledge of the systematic error in the HbA1c measurement is important for correct interpretation of benchmarking results if HbA1c is measured at local laboratories.

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