Annual Out-of-Pocket Costs and Productivity Loss Among Patients with Diabetic Kidney Disease Compared to Type 2 Diabetes Mellitus

Abstract

Thesis (Master's)--University of Washington, 2020Background Type II diabetes mellitus (T2DM) is a chronic disease of impaired glucose homeostasis characterized by both insulin resistance and a decrease in insulin production. Disease progression may lead to multisystem complications including the development of diabetic kidney disease (DKD). Though the association of T2DM and DKD with poor health outcomes and increased health care costs has been studied, there remains a paucity of literature assessing the incremental impact of DKD versus T2DM on outcomes and costs. Objective The objective of this study was to compare total annual out-of-pocket costs and workplace productivity loss measured by absenteeism and short-term disability between patients with T2DM compared to patients with DKD. Methods Data from the IBM/Watson MarketScan Commercial Claims and Encounters (CCAE) and Health and Productivity Management (HPM) Databases were used to conduct this retrospective cohort study (2013-2018). Adult patients ≥18 years with ≥2 unique service claims with a principal or secondary diagnosis for T2DM within 6-months during the enrollment period were assigned to the T2DM cohort. Among the T2DM cohort, a subset of patients with an additional ≥2 unique service claims for CKD during the enrollment period were selected and assigned to the DKD cohort. All patients were continuously enrolled for 12-months prior to the index date, beginning at the date of first T2DM claim. Inclusion in either cohort was mutually exclusive. Patients with incident DKD after the index date were followed in the T2DM cohort until the second CKD claim and were then followed in the DKD cohort thereafter. Individuals also present in the HPM databases were included in the sub-populations for the workplace absence or short-term disability outcomes. We used the Kaplan-Meier Sample Average approach to estimate outcomes using 1-month intervals during the follow-up period. To evaluate uncertainty, we performed a nonparametric bootstrap with 1000 replicates to generate 95% credible intervals (CIs). Results In the primary population (N=411,887), the mean annual out-of-pocket cost was significantly higher among patients with DKD ($151 [95$147, $153]) compared to those with T2DM ($118 [95% CI: $114,$124]), with a mean difference of $327.5 (95$326.8, $328.2). The mean annual productivity loss due to workplace absenteeism was found to be similar between those with DKD (227 hours [219 hours, 236 hours]) and T2DM (217 hours [187 hours, 226 hours]), with a mean difference of 21.7 hours (95% CI: 21.0 hours, 22.3 hours). Significantly higher mean annual short-term disability was observed among those with DKD (4.6 days [4.4 days, 4.8 days]) compared to those with T2DM (2.8 days [2.3 days, 3.4 days]), with a mean difference of 1.78 days (95% CI: 1.76 days, 1.80 days). Conclusions Patients with DKD were found to have higher mean annual OOP costs and experience more days with short-term disability claims compared to patients with T2DM. These results quantify the economic burden of T2DM and DKD from a patient and employer perspective and may be useful in economic evaluations to inform health care decision-making