Date of Award

Spring 5-16-2014

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

First Advisor

Ruiyan Luo

Second Advisor

Sheryl Strasser

Abstract

BACKGROUND: There are many studies that have documented the increasing impact of stress and anxiety on an individual’s health and well-being. Everyone handles stress and anxiety differently with these conditions having varying physiological effects. To better recognize whether or not a person may need help in tackling these conditions, scholars have developed reliable validated instruments. Two prominent instruments that effectively assess stress and anxiety levels are the Perceived Stress (PSS) and Generalized Anxiety Disorder (GAD-7) scales. Furthermore, the literature has shed light onto the importance of the carotid intima-media thickness (c-IMT) measurement as a tool in evaluating the risk of cardiovascular disease. After all, heart disease has been reported as being the number one killer of Americans in recent years. The specific aims of this study were to determine if there was an association between perceived stress / generalized anxiety and c-IMT (static association), and also if higher levels of perceived stress / generalized anxiety result in a significant increase in c-IMT (changes over time).

METHODS: Data was collected on about 700 participants comprised of employees from Emory University in Atlanta, Georgia. At baseline, six, twelve, and twenty-four months, the largest number of participants had completed and calculated their scores on the PSS and GAD-7 scales. At these same time points, participants had their IMT measured and recorded for the left and right common carotid arteries by a trained sonographer of the Emory Predictive Health Institute. Due to incomplete measurements and scores, only 228 participants were included for statistical analyses. This was still considered a suitable sample size given that this study only involved four measurement time points. Various statistical models were fitted for the data. All variables in the models were treated as categorical except for time which was continuous. Four separate models were built that included the variables perceived stress, age group, gender and time. In a similar manner, four models were built that included the variables generalized anxiety, age group, gender and time. AIC values, -2 log-likelihoods, partial correlations, p-values, and other relevant information were reported for these models. All statistical analyses were performed using the Statistical Analysis System (SAS), version 9.2.

RESULTS: The mean c-IMT measurements for the Emory participants were higher than established normal ranges. A strong correlation existed between the PSS and GAD-7 two-year averages when treated as continuous variables (.7316, p <.0001). Likewise, a meaningful relationship existed when both scales were categorical (.4154, p < .0001). The analyses revealed that the left and right mean IMT measurements for the common carotid arteries modeled a linear trend with an unstructured covariance the best. The partial correlations for perceived stress and generalized anxiety revealed weak, but significant positive associations with the mean c-IMT measurement. Although the slope coefficients were not significant for perceived stress, an increase from below average to above average perceived stress level still resulted in an increase in mean c-IMT measurement. Conversely, mild generalized anxiety was found to be statistically significant in the regression model of the left mean c-IMT. This was after controlling for age group and gender. The p-value for mild generalized anxiety was 0.0258, and the slope coefficient was 0.04856. IMT measurements were consistently higher for males on both sides compared to females. They were also higher on the left side compared to the right.

CONCLUSIONS: Failure to control anxiety could lead to c-IMT soaring to dangerous levels resulting in a myocardial infarction and/or cerebrovascular accident. Individuals should engage in healthy lifestyle practices that lower stress and anxiety levels to decrease the chances of cardiovascular disease. Based on this study’s findings, a person can certainly use their c-IMT readings, as well as their perceived stress and generalized anxiety scores, as indicators that lifestyle modifications may be needed.

Available for download on Tuesday, April 28, 2015

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