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 in the State and the effectiveness of the better-than-average HbA1c testing in Georgia.
- Georgia does not differ statistically from the national average on the three process measures that relate to eye exams, foot exams, and influenza vaccination for adults with diabetes. The absence of a statistically significant difference has to be tempered with the fact that BRFSS samples for individual States are often quite small and probably too small to have the power to detect a difference of the size measured here, even if it exists. Thus, the higher rates of eye exams (statistically significant) are simply inconclusive. When compared to the more stringent benchmark of the best-in-class rates for these measures, however, Georgia is not one of the top 10 percent of States (go to Table 2.1). This is especially true for immunization against influenza where there is almost a 30-percentage-point difference between Georgia's rate and the best-in-class average (30 percent versus 59 percent).
Massachusetts: Figure 3.4.B reveals the following about Massachusetts compared to national norms:
- Massachusetts appears to be close to the national average on all of the NHQR process measures for diabetes care quality, using the test of statistical significance. However, because of the small sample sizes of the BRFSS, consider the magnitude of the differences from the national average. Massachusetts' average for HbA1c testing two or more times per year is 8 percentage points higher than the average State and for flu immunizations its average is 7 points higher — notable differences. In both cases, however, the amount of variation among the States and within Massachusetts makes these statements equivocal, and the higher values could as likely be due to chance as to better performance.
- Massachusetts is not among the top decile States when compared to best-in-class estimates. Massachusetts' lower values are statistically different (go to Table 2.1), which means the differences are unlikely to be chance occurrences compared to the top 10 p