Psychometric testing of the decisional conflict scale: genetic testing hereditary breast and ovarian cancer.

Background: : Hereditary breast and ovarian cancer (HBOC) syndrome is attributed mostly to mutations in the Breast Cancer 1 and Breast Cancer 2 genes (BRCA1/2). Mutation carriers of BRCA1/2 genes have significantly higher risk for developing breast cancer compared with the general population (55%-85% vs. 12%) and for developing ovarian cancer (20%-60% vs. 1.5%). The availability of genetic testing enables mutation carriers to make informed decisions about managing their cancer risk (e.g., risk-reducing surgery). However, uptake of testing for HBOC among high-risk individuals is low, indicating the need to better understand and measure the decisional conflict associated with this process.

Objective: : The aim of this study was to evaluate the reliability and validity of the modified Decisional Conflict Scale for use in decisions associated with genetic testing for HBOC.

Methods: : This cross-sectional cohort study, recruited women who pursued genetic testing for HBOC in two genetic risk assessment clinics affiliated with a large comprehensive cancer center and one of their female relatives who did not pursue testing. The final sample consisted of 342 women who completed all 16 items of the Decisional Conflict Scale. The psychometric properties of the scale were assessed using tests of reliability and validity, including face, content, construct, contrast, convergent, divergent, and predictive validity.

Results: : Factor analysis using principal axis factoring with oblimin rotation elicited a three-factor structure: (a) Lack of Knowledge About the Decision (α = .97), (b) Lack of Autonomy in Decision Making (α = .94), and (c) Lack of Confidence in Decision Making (α = .87). These factors explained 82% of the variance in decisional conflict about genetic testing. Cronbach's alpha coefficient was .96.

Discussion: : The instrument is an important tool for researchers and healthcare providers working with women at risk for HBOC who are deciding whether genetic testing is the right choice for them.