Date of Award

12-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Nursing

Research Advisor

Michael A. Carter, DNSc

Committee

Joe K. Bissett, MD Patricia A. Cowan, PhD Patricia M. Speck, DNSc Elizabeth A. Tolley, PhD

Abstract

Area of Investigation and Hypothesis: Decreased heart rate variability (HRV) has been used as a predictor of cardiac and all-cause mortality. Studies have documented decreased HRV in a variety of conditions, including posttraumatic stress disorder (PTSD), depression, age, coronary artery disease (CAD), diabetes mellitus (DM), and tobacco use but improvement with beta blocker (BB) treatment. No prior study evaluated the relationship between military sexual trauma (MST) exposure and HRV outcomes. The hypothesis of this study was that female veterans exposed to MST would have lower time domain HRV measures than a reference cohort reporting non-exposure. Methods and Procedures: Electronic medical records (EMR) containing Holter and electrocardiogram (ECG) tracings of female veterans 21 to 86 years of age examined from January 2007 through December 2010 at a Veterans Affairs (VA) Medical Center were used for this historical cohort study. The sample contained female veterans with MST exposure (n = 27) and a reference group (n = 99) with no reported MST. Log transformed standard deviation of all normal to normal intervals (SDNN) and log transformed square root of the mean of the sum of the squares of differences between adjacent normal to normal intervals (RMSSD) were the primary comparison outcome measures and were derived from the mean of three 10-second ECG or Holter tracings for each subject. The MST universal screening tool, the PTSD ChecklistCivilian instrument, and the Patient Health Questionnaire-9 instrument for depression were used by the VA for diagnosis. History of MST, PTSD, depression, CAD, DM, tobacco use, and beta blocker treatment was obtained from the EMR. The expedited study was approved by the University of Tennessee Health Science Center and VA institutional review boards and the VA Research and Development Committee. Results: The mean (M) measures of log transformed SDNN and standard deviations (SD) differed significantly (p = .0001) between subjects with MST exposure (M = 3.25, SD = 0.11) and the reference cohort (M = 3.74, SD = 0.06). The mean measures of log transformed RMSSD and SD differed significantly (p = .001) between female veterans with MST exposure (M = 3.43, SD = 0.10) and the reference cohort (M = 3.81, SD = 0.05). Eighty percent of female veterans with MST had PTSD. Female veterans with MST (M = 41, SD = 11.67) were significantly (p = .002) younger in years than those with no MST exposure (M = 51, SD = 14.14). The projected SDNN of a 25 year old with MST exposure was comparable to that of a 69 year old without MST, while the RMSSD of a 25 year old with MST exposure was comparable to that of an 81 year old. Conclusions: Female veterans with MST had significantly lower HRV at a younger age compared to a reference cohort that contained veterans with PTSD from other traumas, including combat-related PTSD. Early HRV decline in female veterans with MST may increase risk of premature death.

DOI

10.21007/etd.cghs.2011.0174

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Nursing Commons

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