Effect of improved glycemic control on health care costs and utilization

Context Because of the additional costs associated with improving diabetes management, there is interest in whether improved glycemic control leads to reductions in health care costs, and, if so, when such cost savings occur, Objective To determine whether sustained improvements in hemoglobin A(1c) ( HbA(1c)) levels among diabetic patients are followed by reductions in healt h care utilization and costs. Design and Setting Historical cohort study conducted in 1992-1997 in a staf f-model health maintenance organization (HMO) in western Washington State. Participants All diabetic patients aged 18 years or older who were continuo usly enrolled between January 1992 and March 1996 and had HbA(1c) measured at least once per year in 1992-1994 (n = 4744). Patients whose HbA(1c) decr eased 1% or more between 1992 and 1993 and sustained the decline through 19 94 were considered to be improved (n=732), All others were classified as un improved (n=4012). Main Outcome Measures Total health care costs, percentage hospitalized, and number of primary care and specialty visits among the improved vs unimprov ed cohorts in 1992-1997. Results Diabetic patients whose HbA(1c) measurements improved were similar demographically to those whose levels did not improve but had higher baseli ne HbA(1c) measurements (10.0% vs 7.7%; P<.001). Mean total health care cos ts were $685 to $950 less each year in the improved cohort for 1994 (P=.09) , 1995 (P=.003), 1996 (P=.002), and 1997 (P=.01). Cost savings in the impro ved cohort were statistically significant only among those with the highest baseline HbA(1c) levels (<greater than or equal to>10%) for these years bu t appeared to be unaffected by presence of complications at baseline. Begin ning in the year following improvement (1994), utilization was consistently lower in the improved cohort, reaching statistical significance for primar y care visits in 1994 (P=.001), 1995 (P<.001), 1996 (P=.005), and 1997 (P=. 004) and for specialty visits in 1997 (P=.02). Differences in hospitalizati on rates were not statistically significant in any year. Conclusion Our data suggest that a sustained reduction in HbA(1c) level amo ng adult diabetic patients is associated with significant cost savings with in 1 to 2 years of improvement.