Comparative evaluation of quality of diabetes care within a population using discrete HbA1c thresholds versus longitudinal trends within a defined time period

Abstract

Background: HbA1c is a quality measurement for a population's diabetes care. Currently, discrete values are used to judge the care quality. However, an improved trend may have been achieved without reaching a discrete threshold. We aimed to compare the quality of glycaemic care using discrete thresholds versus longitudinal trends of a patient's HbA1c.

Methods: We derived a study population of 4062 with two consecutive HbA1c's within 1-6 months. We used current discrete thresholds and then used these to define the longitudinal thresholds (the change in HbA1c between the first and second measurement).

Results: We found that even with discrete thresholds, overall care was improving with 61% (Excellent care), 13% (Good care), 13% (Average care) and 13% (Poor care) turning into 68%, 12%, 11% and 9%, respectively (χ² 3335, p<0.0001). Using longitudinal trends shows a greater improvement of care with the original values achieving 74%, 7%, 9%, 7% and 4%, respectively (χ² 4111.3, p<0.0001). There was an additional 28% (Good care), 15% (Average care) and 12% (Poor and Very poor care) who with longitudinal trends improved to an excellent category without being identified as such.

Conclusion: Our study highlights the need to consider longitudinal trends when measuring quality of diabetes care.

Keywords: diabetes & endocrinology.