Predicting adherence to a dietary regimen in a cancer prevention trial

Persistent Link:
http://hdl.handle.net/10150/282207
Title:
Predicting adherence to a dietary regimen in a cancer prevention trial
Author:
Vargas de Robles, Perla Amalia, 1955-
Issue Date:
1996
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In light of the importance of preventive measures to effectively reduce the mortality rate associated with colon cancer, and the importance of adherence to treatment in the study of cancer prevention, the aim of this study was to identify variables that explain adherence to treatment in a long term, colon cancer prevention clinical trial. The Wheat Bran Fiber study is a double-blinded, placebo-controlled trial evaluating the efficacy of daily wheat bran fiber supplementation on polyp recurrence in 1,400 randomized persons with adenomatous colon polyp history. Adherence was defined as consumption of the cereal regimen during the specific evaluation period. It was evaluated through the count of returned unopened cereal boxes, and self-monitoring. Data were collected prospectively and discretely during clinic visits that took place approximately every three months. The Life-Style Questionnaire was constructed as a theory driven instrument with three major components: past adherence behavior, social network and self-motivation. I was given a baseline to 910 participants. The evaluation of potential predictors of attrition was conducted using survival analysis techniques. Specifically, a Weibull distribution was used to model the data. Demographic characteristics, physiological changes, and psychological variables constituted the explanatory variables of the model. The two most important predictors of attrition in this study, for both males and females, were exposure to high fiber and experiencing side effects, whether or not study related. Other significant predictors were self-motivation and adherence at baseline for males, and self-motivation, smoking history, and study expectations for females. One of the most interesting findings is the difference in risk between males and females. The higher hazard for females when toxicities were present suggests that women have more difficulties managing side effects. Also, smoking history was not a significant predictor of the hazard for males. Although the reason of such difference is unknown, it can be speculated that the motivations for and the circumstances under which males and females smoke might be completely different. Overall, these results confirm the multifactorial determination of attrition as a time-to-event phenomenon.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Psychology, Behavioral.; Health Sciences, Oncology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Psychology
Degree Grantor:
University of Arizona
Advisor:
Bechtel, Robert B.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titlePredicting adherence to a dietary regimen in a cancer prevention trialen_US
dc.creatorVargas de Robles, Perla Amalia, 1955-en_US
dc.contributor.authorVargas de Robles, Perla Amalia, 1955-en_US
dc.date.issued1996en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn light of the importance of preventive measures to effectively reduce the mortality rate associated with colon cancer, and the importance of adherence to treatment in the study of cancer prevention, the aim of this study was to identify variables that explain adherence to treatment in a long term, colon cancer prevention clinical trial. The Wheat Bran Fiber study is a double-blinded, placebo-controlled trial evaluating the efficacy of daily wheat bran fiber supplementation on polyp recurrence in 1,400 randomized persons with adenomatous colon polyp history. Adherence was defined as consumption of the cereal regimen during the specific evaluation period. It was evaluated through the count of returned unopened cereal boxes, and self-monitoring. Data were collected prospectively and discretely during clinic visits that took place approximately every three months. The Life-Style Questionnaire was constructed as a theory driven instrument with three major components: past adherence behavior, social network and self-motivation. I was given a baseline to 910 participants. The evaluation of potential predictors of attrition was conducted using survival analysis techniques. Specifically, a Weibull distribution was used to model the data. Demographic characteristics, physiological changes, and psychological variables constituted the explanatory variables of the model. The two most important predictors of attrition in this study, for both males and females, were exposure to high fiber and experiencing side effects, whether or not study related. Other significant predictors were self-motivation and adherence at baseline for males, and self-motivation, smoking history, and study expectations for females. One of the most interesting findings is the difference in risk between males and females. The higher hazard for females when toxicities were present suggests that women have more difficulties managing side effects. Also, smoking history was not a significant predictor of the hazard for males. Although the reason of such difference is unknown, it can be speculated that the motivations for and the circumstances under which males and females smoke might be completely different. Overall, these results confirm the multifactorial determination of attrition as a time-to-event phenomenon.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectPsychology, Behavioral.en_US
dc.subjectHealth Sciences, Oncology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePsychologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBechtel, Robert B.en_US
dc.identifier.proquest9720578en_US
dc.identifier.bibrecord.b34507310en_US
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