Assessing the impact of diabetes-related comorbidities and care on the hospitalization costs for patients with diabetes mellitus in Japan

Objective: Because diabetes mellitus (DM) has been highlighted in several healthcare sectors, variations in the case mix of DM should be evaluated to promote effective disease management. Using a Japanese administrative database (2003), we investigated the impact of DM-related comorbidities and of their relevant care processes on healthcare costs incurred during hospitalization. Methods: Of 283,771 hospital admissions across 174 acute care hospitals, 27,853 patients with DM were analyzed. The following variables were analyzed according to age (<65 or ≥65 years), the presence of comorbidities, demographic characteristics, procedure-related complications, insulin use, surgical procedures (percutaneous minimally invasive intervention, hemodialysis, ventilation, and rehabilitation), length of stay (LOS), and total charge (TC; US$1=Y90). Multivariate analyses were applied to investigate the effects of DM-related complications and care processes associated with DM on TC. Results: The mortality and procedure-related complication rates were 2.1% and 2.7%, respectively. There were significant differences in the frequencies of comorbidities by age category. Among DM-related comorbidities, peripheral vascular disease had the greatest impact on increasing the LOS or TC. Minimally invasive procedures, hemodialysis, ventilation, and procedure-related complications were significant determinants of TC. Hemodialysis and invasive surgical procedures were independent predictors of procedure-related complications. Conclusions: DM-related comorbidities and care process representative of the DM case mix were responsible for variations in healthcare costs during hospitalization.