A Secondary Analysis of Heart Rate Variability and Upper Gastrointestinal Symptoms in Persons with Irritable Bowel Syndrome

Thesis (Ph.D.)--University of Washington, 2022University of Washington Abstract A Secondary Analysis of Heart Rate Variability and Upper Gastrointestinal Symptoms in Persons with Irritable Bowel Syndrome Li Juen Chen Chair of the Supervisory Committee:Margaret McLean Heitkemper Department of Biobehavioral Nursing and Health Informatics This dissertation evaluates the relationships between heart rate variability (HRV) and upper gastrointestinal (GI) symptoms (i.e., heartburn, nausea); it also provides an update on cognitive behavioral therapy in persons with irritable bowel syndrome (IBS). IBS is a chronic GI condition and highly prevalent disorder of gut-brain interaction (DGBI) with a negative impact on an individual’s quality of life. While the primary symptoms of IBS are abdominal pain and bowel alterations, patients with IBS often report upper GI symptoms and autonomic nervous system (ANS) dysfunction. HRV indices collected from electrocardiogram recordings have been useful for quantifying ANS function and risk stratification in various conditions such as DGBIs, somatic symptoms, and mood disorders. The DGBIs affect individuals across the age spectrum, with the prevalence of some symptoms increasing while others decreasing. Yet, information is lacking on age differences in daily GI symptoms and HRV as indicators of ANS dysregulation in women with IBS. This dissertation includes two papers that describe the links between HRV and upper GI symptoms in IBS patients and a third paper that is a review of cognitive behavioral therapy (CBT), a non-pharmacologic strategy focused on reducing negative perceptions about IBS. The first paper reviews the current literature on HRV spectral analysis as measured by electrocardiogram in persons with IBS and a comparison group of healthy controls (HCs). In addition, the relationship of HRV indices and upper GI symptoms were examined in the IBS and HC groups. A total of eleven observational studies recruited 1039 participants (IBS n=679 and HCs n=360) were found. Baseline or nighttime HRV did not differ between the IBS and HC groups in nine studies. Reduced HRV was found in two studies and increased HRV was found in one study of the IBS patients compared to a HC group. However, group differences in HRV indices were influenced by body posture, time of day, and visceral stressor used. Only three studies assessed upper GI symptoms; none found any associations between HRV indices and upper GI symptoms in either the IBS or HC groups. This suggests that only a small subgroup of persons with IBS have autonomic dysregulation. Various HRV measures and study designs made the comparisons across studies difficult. The second paper is a secondary data-based analysis that describes the relationships between upper GI symptoms, somatic symptoms, emotional distress, and HRV indicators in younger and older women with IBS. When controlling body mass index and age, nausea was negatively correlated with HRV measures reflecting decreased vagal modulation. Mixed sympathetic and/or parasympathetic nervous activity was also found within older women with IBS. In this community- and clinic-recruited sample, there are age-related differences in associations of daily upper GI symptoms and indices of ANS function in women with IBS. The third paper provides a literature update on CBT research in IBS, particularly considering the dose of treatment, route of delivery (in-person versus web- and telephone-based delivery), and outcome measures. Twelve studies were reviewed for comparing CBT delivered with in-person, telephone, and web for the management of IBS symptoms among adults with IBS. The dose of treatment varied from 4 to 10 sessions. Six different scales measured various outcomes. CBT is an effective treatment for IBS symptoms regardless of the dose and the route of treatment. However, it is difficult to compare the effectiveness of these RCTs due to the various CBT protocols, combined routes of therapy delivery and different outcome measures used. This dissertation explores a subgroup of individuals with IBS who have ANS dysregulation; the age-related differences between HRV measures and severity and frequency of upper GI symptoms (i.e., heartburn, nausea); it also provides the information, CBT is effective when delivered via in-person versus telephone and/or web. However, no evidence supports one delivery route is better than the others. Of three papers provide a better understanding of ANS activity and upper GI symptoms (I.e., heartburn, nausea) as well as the effectiveness of CBT in persons with IBS