Date of Award


Document Type


Degree Name

MS in Pharmacy Administration


Pharmacy Administration and Public Health

First Advisor

Wenchen Wu

Second Advisor

Martha Mackey

Third Advisor

Taehwan Park


Background: T2DM patients with depression symptoms (PHQ-2≥3) but without clinical diagnosis remain undiagnosed and untreated. Undiagnosed depression in T2DM patients can exacerbate the patient's health. However, no study has comprehensively evaluated the impact of undiagnosed depression on the direct medical expenditures and HRQoL in T2DM patients. Objective: To estimate the differences in the total expenditures, expenditures by service type, and HRQoL of T2DM patients with diagnosed, undiagnosed, and no depression. Methods: A retrospective, cross-sectional study design was implemented using Medical Expenditure Panel Survey data (2016-2018). T2DM patients were stratified using the ICD-10-CM depression code ("F32") and PHQ-2 screener as : (1) Diagnosed (2) Undiagnosed (PHQ-2 ≥ 3 but without depression diagnosis) (3) No depression. The dependent variable was total healthcare expenditures, office-based, hospital outpatient, emergency room, inpatient hospital, prescription, dental, and home health care expenditures for cost-related outcomes. For HRQoL related outcomes, MCS (mental component summary) and PCS (physical component summary) scores were obtained from the SF-12v2/VR-12 questionnaires. Healthcare expenditures were estimated using GLM (generalized linear model) and a two-part model. Regression analysis was used to examine the impact of depression on the HRQoL. Models were adjusted for independent variables selected using Andersen's behavioral model, and all the expenditures were adjusted to 2018 USD value. Results: We identified 7078 adults with T2DM, of which 8.99% had undiagnosed depression and 16.30% had diagnosed depression. The incremental expenditure of diagnosed depression was $550 (p=0.755), and for patients with no depression was -$4096 (p=0.005) compared to the undiagnosed depression group. The expenditures based on the service type showed no significant differences in the expenditures between the diagnosed and the undiagnosed depression group. A significant difference of -$563 (p=0.017) was found in the home healthcare expenditures of the no depression group than the undiagnosed depression group. Compared to adults with undiagnosed depression, the HRQoL scores (MCS: 4.29; PCS: 3.73; p<0.001) were higher for patients with diagnosed depression. Similarly, those with no depression had higher HRQoL scores (MCS: 14.30; PCS 6.59; p<0.001),than the undiagnosed depression patients. Conclusion: Our findings suggest that if depression symptoms (PHQ≥3) in T2DM patients remain undiagnosed and are not treated, it may contribute to higher expenditures and lower HRQoL. Interventions focused on efficient screening and diagnosis of undiagnosed depression are needed to achieve possible cost savings and better HRQoL.

Available for download on Thursday, August 22, 2024