Changes in prevalence of diabetic complications and associated healthcare costs during a 10-year follow-up period among a nationwide diabetic cohort

Objective: Long-term health and economic consequences of diabetes mellitus are of significant importance to health policy makers to identify the most efficient interventions for disease managements. However, existing data are mainly from simulation models instead of "real-world" data. The objective of this study was to longitudinally evaluate the changes of prevalence of diabetic complications and associated healthcare costs in a nationally-representative diabetic cohort. Methods: We used the 2000-2011 Taiwan's Longitudinal Health Insurance Database (LHID) to conduct a population-based cohort study of 136,372 patients with type 2 diabetes. Diabetic complications of each patient were calculated annually after the cohort entry by the adapted Diabetes Complications Severity Index (aDCSI) score (sum of diabetic complication with severity levels, range 0-13) using diagnostic codes recorded in the LHID. Study subjects were further categorized into six subgroups according to their aDCSI score (0, 1, 2, 3, 4, 5 +) at cohort entry. Healthcare utilizations (including outpatient and inpatient visits) as well as direct medical costs for the six subgroups were estimated annually using patient-level data from the LHID. Results: We found the severity of diabetic complications increased over time, especially for patients with aDCSI score of 2 and above at cohort entry (at 10 years of follow-up: aDCSI = 0 (cohort entry), 2.37; aDCSI = 1, 3.59; aDCSI = 2, 4.60; aDCSI = 3, 5.14; aDCSI = 4, 5.96). There were significant differences in healthcare utilizations and associated medical costs among patients stratified by aDCSI score (e.g. at 1 year after cohort entry, mean counts of inpatient visits: 0.14 vs. 1.81 for aDCSI = 0 vs.5 +). Relatively high healthcare utilizations and associated medical costs in the first year of cohort entry were observed for patients with aDCSI score of 4 and above at cohort entry. Conclusions: We provided the important empirical data for patient-level longitudinal changes in diabetic complications and associated healthcare utilization and medical costs among patients with diabetes. (C) 2015 Elsevier Inc. All rights reserved.