A risk assessment score could help identify individuals with type 1 diabetes who are at higher risk of driving mishaps and who may benefit from interventions to reduce their risk, a new study suggests.
Writing in the June edition of Diabetes Care, Daniel J. Cox, MD, of the University of Virginia, Charlottesville, and his coauthors reported on their efforts to develop and validate a “Risk Assessment of Diabetic Drivers” (RADD) scoring system.
In the first part of the two-part study, 1,371 drivers with type 1 diabetes filled out a series of questionnaires about diabetes and driving, then recorded their driving mishaps over the subsequent year (Diabetes Care. 2017;40:742-50).
This revealed that annual driving distance, peripheral neuropathy, number of past hypoglycemia-related driving mishaps, and the degree to which the individual is bothered by hypoglycemia in general were all significantly associated with a risk of future driving incidents.
Based on this, the authors developed a scoring system using these factors and identified the optimum cut-off point for maximum sensitivity and specificity.
“The area under the curve, a global measure of model performance, was estimated to be 0.73, indicating that the model performed better than chance at classifying participants into the two risk categories,” the authors wrote.
When applied to the original participants, the model classified 37.5% of them as being high-risk. This group had an average of 3.03 driving mishaps over the 12-month follow-up, compared with 0.87 mishaps in the participants who fell into the lowest 37.5% of risk (P = .002).
In the second part of the study, 1,737 drivers with type 1 diabetes completed a version of the scoring questionnaire online, and 118 low-risk and 372 high-risk individuals were recruited.
The high-risk individuals were randomized either to a 2-month online intervention that aimed at helping people with type 1 diabetes anticipate, prevent, detect, and treat hypoglycemia while driving, as well as a program of motivational interviewing, the online intervention alone, or routine care, with 12 months of follow-up. The low-risk individuals all received routine care only.
As with the first part of the study, researchers saw a significantly lower number of driving mishaps in the low-risk participants, compared with the high-risk participants (1.65 mishaps per driver per year vs. 4.26 mishaps per driver per year; P less than .001).
After adjusting for other factors such as age, sex, method of insulin delivery, and hypoglycemia awareness, the rate of mishaps was still 2.83 times higher in the high-risk group, compared with the low-risk group (P less than .001).
The authors noted that their RADD scoring system did have a false-negative rate of 24%, classifying people as low-risk even though they reported more than one driving mishap in the following 12 months.
“This illustrates that any driver has a risk of being involved in a collision or receiving a citation, and any driver with type 1 diabetes has the additional risk of experiencing disruptive extreme [blood glucose (BG)] that can result in a mishap while driving,” they wrote. “While, ideally, all drivers with type 1 diabetes should measure their BG before driving, they should at least be counseled that, whenever they take more insulin, eat fewer carbohydrates, or engage in more physical activity than usual, they should measure their BG before driving.”
With respect to the impact of the intervention and motivational interviewing, researchers found no significant differences in the rate of mishaps between the groups who received intervention plus interview and those who received the intervention alone, and, as a result, combined these two groups into one.
The high-risk group who underwent the online intervention had fewer driving mishaps than did the high-risk group who received routine care. However, they still had 1.58 times more incidents than did the low-risk individuals who received routine care.
The intervention decreased the risk of mishaps associated with hypoglycemia in high-risk individuals, compared with that in those who recieved routine care, but these individuals still had a higher incidence of hypoglycemia-associated mishaps, compared with the low-risk individuals.
“It is also important to note that [the online intervention] only affected hypoglycemia-related driving mishaps, not hyperglycemia- or nondiabetes-related mishaps,” the authors wrote.
The study was funded by the National Institutes of Health and supported in-kind by LifeScan, Abbott Laboratories, MyGlu.com, dLife.com, and Dex4.com.