Date of Award

Spring 2017

Document Type

Open Access Dissertation

Department

Pharmacology, Physiology and Neuroscience

Abstract

Introduction

Multimorbidity, commonly defined as having two or more chronic conditions, is a major burden in middle-aged and older adults, causing increased risks for hospitalizations, medical care costs, and even death. One condition with severe adverse effects in the older population is depression. Depression has been shown to increase ones social isolation while compounding self-management, eventually increasing ones chance for mortality. Multimorbidity coupled with depression has been shown to increase the risk for mortality; however, these results are typically based on a one-time depression evaluation. The main objective of this study is to examine if depressive symptom trajectories modifies the effect multimorbidity has on all-cause and cause-specific (cancer and cardiovascular disease) mortality.

Methods

Data obtained from the Health and Retirement Study (HRS) was used for this study. A multimorbidity variable was created using data from the 2004 wave of the HRS. Three distinct depressive symptom trajectories were created using the biennial waves from 1998, 2000, 2002, and 2004 (persistently low, persistently moderate, and persistently high). Deaths were analyzed and categorized from the 2006, 2008, 2010, 2012, and 2014 datasets. Confounders were analyzed in 2004 and were included based on their vi

presence in similar studies. There were a total of 13005 individuals aged 50 and older who fit the criteria for this study. Separate Cox proportional hazards models were created and ran to examine the association depressive symptom trajectories have on modifying the effect multimorbidity has on all-cause and cancer mortality. Fine and Gray models were created and ran to examine the association depressive symptom trajectories have on modifying the effect multimorbidity has on cardiovascular disease (CVD) mortality.

Results

From the final study population, 58.5% had persistently low depression symptoms, 24.9% had persistently moderate depression symptoms, and 16.6% had persistently high depression symptoms. We found depressive symptom trajectories to significantly modify the association between multimorbidity and cardiovascular mortality, specifically among individuals who had three or more chronic conditions. The greatest risk of cardiovascular death was among individuals who had three or more chronic conditions and had persistently high depressive symptom trajectories (HR: 1.85; 95% CI: 1.22, 2.79). Depressive symptom trajectories did not significantly modify the association between multimorbidity and all-cause or cancer mortality.

Conclusion

The findings from this study found that depressive symptom trajectories did not modify the risk of all-cause or cancer-mortality in multimorbid individuals. Depressive symptom trajectories did modify the association between multimorbidity and cardiovascular mortality. Findings from this study partially suggest that depressive symptom trajectories may help to further stratify people who are at a higher risk for CVD mortality. More studies need to be conducted to see if depressive symptom trajectories modify the risk of death in all-cause and cancer-mortality when taking into account the combination of diseases and the severity of the illness. Managing individuals with persistent depressive symptoms and comorbid diseases should be explored to see if properly managing these illnesses could mitigate the mortality effects seen.

Rights

© 2017, Katherine Reynolds O’Shields

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