ted as a black diamond when it is statistically different from the national average or as a black-bordered white diamond when it is not statistically different from the national average.
The solid black diamond in Figure 3.3 shows that State A's rate compared to the national average is considered a statistically significant difference and probably is not attributable to just random variation that appears among the States and within each State. It may well represent some practice difference in State A that is not common nationally. What that difference is caused by cannot be deciphered from these data. Local insights and exploration are needed to understand underlying factors that might influence State A's rate of HbA1c testing.
The black-bordered white diamond in Figure 3.3 indicates that State A's rate compared to the national average is not considered a statistically significant difference and could as easily occur because of random variation as because of any specific practice by health care providers in State A. (Statistical significance and how it is determined is explained in Appendix E.)
In general (although not shown for all States, here), when individual States are tracked across diabetes measures, it becomes apparent that there is uneven performance across measures. No single State consistently ranks highest or lowest across all measures. Thus, all States have some room for improvement compared to national benchmarks and clinical guidelines for the treatment of people with diabetes.
Four States Compared to Benchmarks
To show how States may want to examine their own estimates, four States are compared to national, regional, and best-in-class State-average benchmarks, below. The national average and best-in-class average, when used together, summarize key information across the States and enable graphical comparisons to be simplified as bar charts (go to Figures 3.4.A, 3.4.B, 3.4.C, and 3.4.D).
In the bar charts, statistical significance from the national average is represented by a bold value at the top of the State bar. State values that are not bold are not statistically distinguishable from the national average. (For a discussion of how to consider statistical significance, go to the previous section on Understanding State Variation.) Also, statistical tests have been performed to compare the State average to the best-in-class average. These test results are presented in Table 2.1 in Module 2: Data.
The example States were chosen because each comes from a different region of the country and, at the same time, they represent a range of experiences — States performing above or below the national average on individual measures and States with longstanding and relatively new quality improvement programs in diabetes prevention and control. By using four States, it is easier to show the nuances of making comparisons with limited data. The graphical and statistical analysis below can be applied to any State collecting these measures through the BRFSS.
Each of these States is described in terms of the four diabetes care process measures explored generally above. Descriptions of their quality improvement activities can be found in the Module 4: Action.
Georgia: Figure 3.4.A reveals two facts about diabetes care in Georgia compared to national norms:
- People with diabetes in Georgia are more likely than the national norm to report having had two or more HbA1c test in the past year. This is a statistically significant finding and suggests that Georgia health care professionals are aware of the importance of glycemic control, are testing their patients, and may be educating their patients about glycemic control. Whether they are successful in helping their patients control their blood glucose cannot be determined from these data. It is possible that Georgia physicians see a more advanced stage of diabetes among their patients and are therefore more concerned about their patients and are testing them more frequently. Special data collection would be necessary to evaluate the blood glucose levels of people with diabetes i