Tuesday, 8 April 2008

Average Daily Risk Range (ADRR)

The indicator ADRR was introduced in the scientific paper Evaluation of a New Measure of Blood Glucose Variability in Diabetes by Dr. Boris Kovatchev, Erik Otto, Daniel Cox, Dr. Linda Gonder-Frederick and William Clarke.

The ADRR measures the risk induced by high variability of blood glucose readings. It tries to weigh low and high BG values in an equal fashion. Behind this are two fundamental thoughts about variability and its risks:

1) low blood glucose values are an acute risk. Furthermore patients with many low values will try to prevent this from happening. They do this by seeking higher overall regions. Thus they will seek higher target values or reduce their insulin doses. This tendency will likely degrade their HbA1c performance.

2) high variability of blood glucose readings is risky in the long term. A number of studies found that, in addition to causing cardiovascular complications, cyclic hyperglycemia is an independent contributor to chronic cardiovascular disease and increased mortality. Therefore the knowledge about the glycemic variation is important to develop strategies to narrow down the variability.

The ADRR tries to give a quality indication for both types of risks with these ranges:

Low risk: 0 <= ADRR < 20

Moderate risk: 20 <= ADRR < 40

High risk: 40 <= ADRR

Conclusion: the ADRR is an interesting indicator for risks that are not necessarily reflected by the HbA1c. By calculating the ADRR monthly patients get immediate feedback how their strategies to prevent low values and high variability have worked out for them. These positive side effects of the ADRR convinced our team to implement the ADRR in future versions of the Glucosurfer.

Update: It came to our knowledge that the ADRR is patended by the University of Virginia (USA). Therefore we have asked its Patent Foundation to grant us the right to use the ADRR in our non-commercial project. Let's hope that our project will convince the University to share its property with us and our users.