Electronic Theses and Dissertations

Date

2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Health Systems & Policy

Committee Chair

SangNam Ahn

Committee Member

Aram Dobalian

Committee Member

Meredith Ray

Committee Member

Kenneth Ward

Abstract

In this three-paper dissertation, we used longitudinal data from the Health and Retirement Study (HRS) to investigate prospective associations between time-varying insomnia symptoms (difficulty initiating sleep, difficulty maintaining sleep, early-morning awakening, non-restorative sleep) and incident heart failure (HF), cognitive impairmentno dementia (CIND), and all-cause mortality among middle-aged and older adults (aged 50 years). In each study, we implemented a marginal structural modeling approach to generate the average causal effects of insomnia symptoms, while taking into account time-dependent biological, psycho-cognitive, behavioral, and lifestyle factors, and adjustments for selection bias.The first paper employed data from the 2002 through 2018 waves of HRS, with a sample of 12,761 individuals who were free from HF at baseline in 2002. Marginal structural discrete-time survival analyses were conducted. During the 16-year follow-up, 1,730 sample respondents had incident HF. Individuals experiencing one (hazard ratio [HR]=1.22; 95% CI: 1.081.38), two (HR=1.45; 95% CI: 1.211.72), three (HR=1.66; 95% CI: 1.372.02), or four (HR=1.80; 95% CI: 1.252.59) insomnia symptoms had a higher hazard of incident HF than asymptomatic respondents. In the second paper, we used data from a cohort of 14,530 cognitively healthy HRS respondents (2004 baseline) and followed participants for 12 years (through 2016). We evaluated cognitive performance biennially (CIND vs. normal) and then employed marginal structural generalized estimating equations. The association between insomnia symptoms and CIND varied with respondents age. For those 50 to 64 years old, experiencing two (odds ratio [OR]=1.38; 95% CI: 1.191.63) and three or four (OR=1.39; 95% CI: 1.161.65) insomnia symptoms were associated with higher risks of CIND compared to being symptom-free. For those 65 to 74 years old, experiencing three or four insomnia symptoms was significantly associated with the risk of CIND (OR=1.31; 95% CI: 1.081.58). Among respondents aged 75 or older, insomnia symptoms were not associated with CIND. In the third and final paper, we obtained data from 2004 (baseline) through 2018 survey waves of HRS for a sample of 15,511 individuals. During 14 years of follow-up, 5,878 respondents (31.9%) died. We performed marginal structural discrete-time survival analyses. Respondents who experienced one (HR=1.11; 95% CI: 1.031.20), two (HR=1.12; 95% CI: 1.011.23), three (HR=1.15; 95% CI: 1.051.27), or four (HR=1.32; 95% CI: 1.121.56) insomnia symptoms had on average a higher hazard of all-cause mortality, compared to those who were symptom-free. Our findings indicate that insomnia symptoms are significantly associated with incident HF and all-cause mortality among middle-aged and older adults regardless of age category and that the symptoms could negatively impact cognition by increasing the risks of CIND among middle-aged and, to a lesser extent, older adults. Expanding public health awareness about insomnia and increasing screening for insomnia symptoms in at-risk populations can be an essential prevention strategy. Future studies could investigate complex mechanisms linking insomnia symptoms and these adverse health outcomes.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

Notes

embargoed

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