Hemoglobin A1c in the ESRD Population: Status Report

Should Pre-Transplant Hemoglobin A1c Be Used to Predict Post-Transplant Compliance in End-Stage Renal Disease Patients Undergoing Kidney Transplantation?

Background

Patient compliance with immunosuppressive therapy after transplant has impacts on both graft and patient outcomes. For diabetic end-stage renal disease (ESRD) patients who are undergoing evaluation for kidney transplantation in our program, hemoglobin A_1c (HbA_1c) level of >10% is used as a flag that the patient may be at risk for noncompliance and that more comprehensive psychosocial screening is needed prior to transplant. We evaluated the association between pre-transplant HbA_1c level and post-transplant compliance, as no study to date has looked at this in the transplant population.

Material/Methods

The charts of 392 patients who received a kidney transplant at a single institution between July 2008 and June 2012 were retrospectively reviewed. One hundred and sixty-five diabetic patients who received a kidney transplant alone were included in the final analysis. Our predictive variable was HbA_1c level greater than 7.7% based on previous reports in the diabetic population. Outcome measures were graft survival, rejection episodes, unexplained low immunosuppressant levels, and documented noncompliance.

Results

There were no statistically significant differences between the HbA_1c groups of ≤7.7% and >7.7% in outcomes of failed grafts (22.0% and 17.8%, p=0.2), rejection episodes (15.0% and 6.7%, p=0.3), unexplained low immunosuppressant level (46.6% and 37.9%, p=0.3), and documented noncompliance (25.0% and 16.7%, p=0.4).

Conclusions

In diabetic ESRD patients selected for renal transplantation, elevated pre-transplant HbA_1c levels, defined as HbA_1c >7.7%, are not predictive of post-transplant medication compliance. We advocate that this group of patients should not be denied transplant solely on their elevated pre-transplant HbA_1c.

What is the Role of HbA1c in Diabetic Hemodialysis Patients?

The definition of a good glycemic control in patients with diabetes mellitus on hemodialysis is far from settled. In the general population, hemoglobin A1c is highly correlated with the average glycemia of the last 8-12 weeks. However, in hemodialysis patients, the correlation of hbA1c with glycemia is weaker as it also reflects changes in hemoglobin characteristics and red blood cells half-life. As expected, studies show that the association between HbA1c and outcomes in these patients differ from the general population. Therefore, the value of HbA1c in the treatment of hemodialysis patients has been questioned. Guidelines are generally cautious in their recommendations about possible targets of HbA1c in this population. Indeed, the risk of not treating hyperglycemia should be weighed against the particularly high risk of precipitating hypoglycemia in dialysis patients. In this review, a critical analysis of the current role of HbA1c in the care of hemodialysis patients is presented.