Date of Award

6-30-2016

Document Type

Open Access Dissertation

Department

College of Pharmacy

First Advisor

Richard Schulz

Abstract

Introduction: Breast cancer patients with a depression diagnosis before or after cancer diagnosis have increased cost, shorter survival time and reduced adherence to hormone therapy. Treating depression in these patients should improve these outcomes; however, there is scarce literature on this topic. Currently, no study has determined the association of concurrent depression while adjusting for a history of depression or treating depression with antidepressants with cost, survival and adherence to hormone therapy. This study has two objectives: 1) to determine the association of concurrent depression with cost, survival and adherence to hormone therapy adjusting for a history of depression 2) to determine the association of antidepressant use with cost, survival and adherence to hormone therapy in patients with depression.

Methods: The SEER-Medicare dataset for 2005-2010 was used to address the study objectives. Breast cancer patients with hormone receptor positive cancers diagnosed from 2006 to 2009 were identified from the SEER cancer registry. Those who initiated hormone therapy within a year of cancer diagnosis were included in the initial population. A depression diagnosis was determined using ICD-9 codes. Those who had an ICD-9 code for depression within a year of cancer diagnosis were included in the final sample. Antidepressant use was determined from prescription drug claims and those who had at least one claim after a depression diagnosis were included in the final analysis. Generalized linear models (GLMs) were used to determine the association of antidepressant use with adherence to hormone therapy and the incremental cost of antidepressant use among breast cancer patients with depression. Kaplan-Meier curves were used to determine the initial association of antidepressant use with survival.

Results: The final study population was 10,471 hormone receptor positive breast cancer patients who took hormone therapy within a year of breast cancer diagnosis. Of these patients, 10% had a diagnosis of depression within a year of breast cancer diagnosis. In breast cancer patients with depression, 62% took an antidepressant after their depression diagnosis. Depression was associated with a statistically significant decrease in adherence (OR 0.81; 0.71-0.93) in the adjusted model. Depression had a statistically significant 30% decrease in survival in the adjusted model. Depression was associated with increased cost ($21,978.75) in the adjusted model; however, this was not statistically significant. Adjusted general antidepressant use in breast cancer patients with depression had a non -significant reduction in the odds of adhering to hormone therapy (OR .79; .55-1.14). Those who took antidepressants for a year had a statistically significant increase in the likelihood of adhering to hormone therapy (OR 2.4; 1.61-3.65). Adjusted general antidepressant use was not associated with survival in breast cancer patients with depression. Continual antidepressant use for a year was associated with a statistically significant 60% increase in survival time in breast cancer patients with depression. Adjusted general antidepressant use was associated with a $27,840.50 increase in per patient per year cost; however, this difference is not statistically significant. Continual antidepressant use for 90+ days was associated with a statistically non-significant decrease in per patient per year total medical cost.

Conclusion: Concurrent depression is associated with worse outcomes in breast cancer patients adjusting for having a history of depression. Continual antidepressant use in breast cancer patients with depression is associated with improved adherence to hormone therapy and increased survival time. The benefit of antidepressant use is time dependent and those who with longer use of antidepressants show more improvement compared to those who do not. Antidepressant use increases per patient per year total medical cost; however, this is not a significant increase and continual use might be associated with decreased cost. Extended antidepressant use in the depressed cancer population provides positive benefits to these patients by improving adherence to hormone therapy and survival and potentially reducing cost.

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