Background: Medical complications are the key drivers of the direct medical costs of treating patients with type 2 diabetes mellitus. However, the published literature shows great variability across studies in the number and type of sources from which these costs for diabetes are obtained.
Objective: To provide to researchers a set of costs for type 2 diabetes complications, originally developed for input into an established diabetes model, that are empirically based, clearly and consistently defined and applicable to a large segment of managed care patients in the US.
Methods: Patients with 1 of 24 diabetes-related complications between 1 January 2003 and 31 December 2004 and with evidence of type 2 diabetes were identified using a nationally representative US commercial insurance claims database. Therapy utilization and complication cost data were extracted for all patients for the 12 months following the first identified complication; data for months 13-24 were obtained for a subset of patients with at least 24 months of follow-up enrollment. Medical costs included both the amounts charged by medical providers and the health plan contracted allowed amounts. Costs were expressed as $US, year 2007 values.
Results: A total of 44 021 patients with a minimum of 12 months of continuous follow-up enrollment were identified, with a mean age of 56 years; a subset of 32 991 patients with at least 24 months of continuous health-plan enrollment was also identified. Among the aggregate sample, 74% of patients were receiving oral antidiabetics, 26% were receiving insulin, 43% were receiving ACE inhibitors and 50% were receiving antihyperlipidaemics/HMG-CoA reductase inhibitors (statins) during the first 12 months following the index complication. The majority of patients had at least one physician office visit (99.8%), laboratory diagnostic test (96.2%) and other outpatient visit (97.5%). Six complications (angina pectoris, heart failure, peripheral vascular disease, renal disease, nonproliferative retinopathy and neuropathy) had a prevalence of at least 10%. Allowed amounts for most complications were 30-45% of charges. Myocardial infarction, heart failure and renal disease had the greatest fiscal impact because of the total number of patients experiencing them (7.2%, 14.0% and 11.0%, respectively) and their associated costs; 12-month mean allowed amounts were $US 14,853, $US 11,257 and $US 13,876, respectively, and 12-month mean charged amounts were $US 41,695, $US 30, 066 and $US 34,987, respectively. Similarly, in the subset of 32 991 patients, these three complications had higher allowed and charged amounts over months 13-24 compared with the majority of other complications of interest.
Conclusion: These costing results provide an important resource for economic modelling and other types of costing research related to treating diabetes-related complications within the US managed care system.