Psychometric testing of a scale designed to monitor the psychosocial and behavioral impact of genetic testing for hereditary nonpolyposis colorectal cancer (HNPCC): a pilot study

LeDrew, Holly (2009) Psychometric testing of a scale designed to monitor the psychosocial and behavioral impact of genetic testing for hereditary nonpolyposis colorectal cancer (HNPCC): a pilot study. Masters thesis, Memorial University of Newfoundland.

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Abstract

The purpose of this pilot study was to conduct preliminary psychometric testing on the Hereditary Diseases and Genetic Testing (HD-GT) scale, which was designed to monitor the psychosocial and behavioral impact of genetic testing for hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome. The pilot was part of a larger study which is using a descriptive correlational design with longitudinal components to develop, validate and evaluate monitoring tools for individuals with genetic-based diseases. The framework for this study was the substantive theory, Confronting and Accepting the Challenges of Living in Families with Genetic-Linked Diseases (Way et al., 2008). -- The target population was individuals at 50% risk for inheriting HNPCC who had participated in genetic testing and were informed of their carrier status. Survey respondents were recruited from population-based probands comprising the Provincial Medical Genetics Program of Newfoundland and Labrador. Study participants (N = 75) were similar to the target population in terms of personal and illness-related characteristics. Data were collected by face-to-face interviews, telephone interviews and self-administered surveys between February and May 2008. -- Psychometric testing of the HD-GT scale was based on the work of Ware and Gandek (1998). Preliminary findings are indicative of good data quality and potential usability of the scale under variant administrative conditions. As well, all of the HD-GT subscales met the criteria for Likert scaling assumptions and evidence very good reliability and validity. -- The various subscales of the HD-GT augment what has been reported in the literature and also provide new insights into the psychosocial and behavioral impact of genetic testing for individuals and families with HNPCC. Study findings suggest that the family history of cancer does have a significant impact on decision-making regarding genetic testing. There are also indications that study respondents place high value on having all potentially at-risk family members participate in genetic testing, but are often challenged trying to convince them to accept the need for testing. -- With regard to the genetic testing process, most respondents placed high value on being emotionally prepared for genetic testing and having appropriate information, but not everyone required health care provider or family/friends support. As well, despite experiencing some emotional difficulty while waiting for test results, not everyone required support prior to and during the receipt of results. Most respondents, however, do place high value on receiving a follow-up letter to reinforce their genetic testing results. -- Most respondents understood the importance attached to being proactive in leading a healthy life and participating in cancer screening. They also believed that there was an increased cancer presence among young people in the family. Finally, most family members, young and old alike, wanted information about HNPCC, and were perceived to understand it, but encountered some difficulties in communicating the information to other family members. -- Study findings indicate that the subscales appear to be sensitive enough to measure the wide-range of psychosocial and behavioral implications of genetic testing. However, due to study limitations, generalizability of the findings is cautioned until the larger study is complete. The findings also provide support for previous research and suggest that more research is needed to inform the practice of genetic counseling. There is also a need for further research into the psychological implications of having an inconclusive test result. -- Finally, study findings have important implications for nursing practice. Competencies required for the effective delivery of genetic services need to be built into the scope of professional nursing practice. If nurses are to work effectively with HNPCC families they must have the appropriate knowledge, education and skills to recognize the features of HNPCC, to take thorough patient and family histories, to provide support, and to coordinate care for these individuals.

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