April 2013

Document Type


Degree Name



Oregon Health & Science University


Background: Irritable Bowel Syndrome (IBS) is a common syndrome, affecting 25-45 million people in the United States. Individuals with IBS experience a worse health-related quality of life (HRQOL), as compared to others with chronic diseases. Despite the fact that an individual’s functional conceptualization of their disease has been shown to assist in their coping successfully with chronic illness, little research has examined how adults conceptualize or cognitively represent IBS. Furthermore, little research has examined whether outcomes might be influenced by an individual’s catastrophizing coping style. Purpose: The purpose of this study is to examine the role of the Common Sense Model of Illness Representation in adults with IBS. The study focused on specific components of illness representation and their relationship to HRQOL outcome. The study further examined whether a catastrophizing coping style acted as a mediator in the relationship between the components of illness representation and perceived HRQOL. Sample: Sampling was completed in both the community and in gastroenterology specialty clinics, family medicine and women’s health clinics in Idaho, Connecticut, Missouri, Michigan, Pennsylvania and New Jersey. One hundred and one individuals with IBS between the ages of 30-50 years who were able to read and speak English and did not have a new diagnosis of an organic lower gastrointestinal disorder were recruited. Methods: Data was collected at a single point in time. Instruments used included The Revised Illness Perception questionnaire (IPQ-R), the Catastrophizing subscale of the Coping Strategies Questionnaire, and the Irritable Bowel Syndrome-Quality of Life Measure (IBS-QOL). Data Analysis: Descriptive statistics were calculated to describe the components of illness representation, catastrophizing coping style and healthrelated quality of life (HRQOL) variables. Pearson’s correlation coefficients were computed to quantify the association between the components of illness representation and HRQOL, as well as the components of illness representation and catastrophizing coping style, and catastrophizing coping style and HRQOL. A three-step regression analysis was performed to examine catastrophizing coping style as a mediator in the relationship between the components of illness representation and HRQOL. Results: Participants who view their IBS as having a great number of symptoms, negative consequences, chronic in nature, poor control (personal & treatment), poor understanding and negative emotional impact were found to have poorer HRQOL. In addition, catastrophizing coping style was used more frequently in those with a greater number of symptoms, who reported more negative consequences, higher chronicity and greater negative emotional impact. The more frequent use of catastrophizing coping style was associated with poorer HRQOL. Finally, a regression analysis was used according to the statistical mediation model developed by Baron & Kenny (1986). This statistical method was used to analyze the mediator impact of catastrophizing coping style on the relationship of illness representation and HRQOL. The results of this analysis indicated catastrophizing coping style fully mediated the relationship between personal control and HRQOL. In addition, the relationship between the remaining components of illness representation and HRQOL were partially mediated indicating catastrophizing coping style was at least one mediator in this relationship. Conclusion: This study expands the understanding of how individuals who suffer from IBS cognitively and emotionally represent their disease. Through this understanding, methods may be developed for integrating patients’ illness beliefs and coping style into the management of their IBS.




School of Nursing



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