In adults with diabetes, CHD, hypertension, and depression spectrum disorders more strongly predicted future costs than the A1c level.
The purpose of this study was to assess the impact of baseline A1c, cardiovascular disease, and depression on subsequent health care costs among adults with diabetes.
A prospective analysis was performed of data from a patient survey and medical record review merged with 3 years of medical claims. Costs were estimated using detailed data on resource use and Medicare payment methodologies. Generalized linear models were used to analyze costs related to clinical predictors after adjusting for demographic and socioeconomic factors.
In multivariate analysis of 1,694 adults with diabetes, 3-year costs in those with coronary heart disease (CHD) and hypertension were over 300% of those with diabetes only ($46,879 vs. $14,233). Depression was associated with a 50% increase in costs ($31,967 vs. $21,609). Relative to those with a baseline A1c of 6%, those with an A1c of 10% had 3-year costs that were 11% higher ($26,408 vs. $23,873). Higher A1c predicted higher costs only for those with baseline A1c >7.5% .
Until recently, most health plans and medical groups that attempt to improve diabetes care have focused primarily on improving A1c. This strategy makes clinical and economic sense when median A1c is high (A1c >8%). However, once median A1c improves to <8%, considerable evidence suggests that other factors (primary and secondary prevention of CHD, control of blood pressure, control of lipids, smoking cessation) may provide more clinical benefits at less cost on a population basis. The significance of these data and the need for greater focus on CHD prevention and control have received insufficient attention.
Despite the limitations of this study, the results are interesting and valuable in that they confirm the importance of A1c as a predictor of costs while placing this observation in a broader perspective. Although A1c remains an important clinical predictor of costs, several other clinical predictors including CHD, hypertension, and depressive symptoms are equal or more important predictors of cost. While continuing to aggressively control A1c, clinicians should place greater emphasis on prevention or control of CHD, hypertension, and depressive symptoms.
Diabetes Care 28:59-64, 2005