Development and Validation of a Diabetes Mellitus Severity Index: A Risk‐Adjustment Tool for Predicting Health Care Resource Use and Costs

Study Objective. To develop and validate a diabetes mellitus‐specific risk‐adjustment tool—the diabetes severity index (DSI)—to assist in predicting health care costs and resources within populations of patients with diabetes. Design. Retrospective analysis of clinical and resource use for patients with a diagnosis of diabetes mellitus. Model estimation was conducted with half the sample, and validation analysis was conducted with the other half. Setting. Southern Arizona Veterans Affairs Health Care System. Patients. Seven hundred thirty‐four patients with diabetes (710 men, 24 women; mean age 66 yrs). Measurements and Main Results. Clinical measures of diabetes severity (known as the DSI) were used to predict three health care resource outcomes: risk of hospitalization, and total and ambulatory health care costs. Validity of the DSI was assessed by comparing the DSI with the revised chronic disease score (CDS). The DSI weights ranged from −471.5–3081.2 for total health care costs, from −304.3–1582.1 for outpatient costs, and −0.19–0.93 for risk of hospitalization. The DSI explained 6–8% of the variance in total and ambulatory costs and performed significantly (p