Date of Graduation

2016

Document Type

Dissertation

Degree Type

PhD

College

School of Pharmacy

Department

Pharmaceutical Sciences

Committee Chair

Usha Sambamoorthi

Committee Co-Chair

Thomas Bias

Committee Member

Kimberly Kelley

Committee Member

Suresh Madhavan

Committee Member

James T Walkup

Abstract

Depression is a highly prevalent chronic condition among the elderly cancer survivors. It is estimated that 5-25% of elderly cancer survivors suffer from depression. Depression co-existing with cancer is associated with many negative health consequences such as high mortality, poor health related quality of life and high healthcare utilization and expenditures. However, depression is treatable with pharmacotherapy, psychotherapy or combination of both. There are no studies that examine the variations in the risk of depression by cancer types and there are few studies that examined the rates of depression treatment among elderly with cancer. In addition, there is lack of evidence on the impact of depression treatment on the economic outcomes of cancer survivors. To fill the knowledge gap, the three related aims of this dissertation were to: (1) examine the variations in the risk of depression by cancer types among elderly with incident breast, colorectal, and prostate cancer; (2) identify the rates of depression treatment and the factors associated with depression treatment among elderly with newly-diagnosed depression and incident breast, colorectal and prostate cancer; (3) analyze the impact of depression treatment on the healthcare expenditures among elderly with newly-diagnosed depression and incident breast, colorectal and prostate cancer. The study used a retrospective cohort study design, using multiple years (2002--2011) of the cancer registry data from the Surveillance, Epidemiology and End Results (SEER) program linked with the Medicare claims data, the American community survey census-tract files and the Area Health Resource Files. In the first aim, among elderly with incident breast, colorectal and prostate cancer (N= 53,821), women with colorectal cancer had 28.0% higher risk of newly-diagnosed depression as compared to women with breast cancer; men with colorectal cancer had 104.0% higher risk of newly-diagnosed depression as compared to men with prostate cancer. Elderly diagnosed with cancer at an advanced stage had a 61.0% higher risk of newly-diagnosed depression as compared to those diagnosed with cancer at an early stage. Elderly with higher number of primary care providers visits had a higher newly-diagnosed depression as compared to those with lower number of primary care providers visits. In the second aim, among elderly with newly-diagnosed depression and incident breast, colorectal and prostate cancer (N= 1,673), 45.7% received antidepressants only; 8.8% received psychotherapy only; 18.4% received combined therapy; and 27.1% received no treatment for depression. Elderly cancer survivors who received ongoing cancer treatment were less likely to receive psychotherapy only, or combination therapy. Elderly living in counties with a higher percentage of psychologists were more likely to receive psychotherapy only, or combination therapy. In the third aim, among elderly with newly-diagnosed depression and incident breast, colorectal and prostate cancer (N= 1,502), the average 1-year total healthcare expenditures after depression diagnosis were higher among those who received depression treatment as compared to no depression treatment. The associations between depression treatment and the higher healthcare expenditures were observed across all types of healthcare expenditures (inpatient, outpatient, prescription drugs, and other expenditures). To summarize, this dissertation found that there are variations in the risk of newly-diagnosed depression by cancer type. Among cancer survivors with newly-diagnosed depression, one-quarter of cancer survivors did not receive any form of depression treatment; cancer-related factors were associated with depression treatment; and depression treatment was associated with increase in short-term healthcare expenditures.

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