The Group-Based Medical Mistrust Scale: psychometric properties and association with breast cancer screening

Background. There is little research on medical mistrust as a barrier to breast cancer screening. This study investigated the psychometric properties of a new scale, the Group-Based Medical Mistrust Scale (GBMMS), and its association with cancer screening attitudes and breast cancer screening practices among African American and Latina women. Methods. Participants were 168 African American and Latina urban women who completed the GBMMS and measures of sociodemographics, cancer screening pros and cons, acculturation, breast cancer screening practices and physician recommendation of such screening. Results. A principal components analysis of GBMMS items revealed three factors that were analyzed as subscales: (1) suspicion, (2) group disparities in health care, and (3) lack of support from health care providers. Convergent validity of the GBMMS was supported by its negative association with perceived benefits of cancer screening and acculturation and positive association with perceived disadvantages of cancer screening. Results further showed that women who reported no previous mammogram or a long-term lapse in mammography participation (>5 years) had significantly higher total GBMMS scores (P < 0.04) compared to women who were either adherent to mammography guidelines or nonadherent but reported a mammogram within the past 5 years. This analysis controlled for physician recommendation. Conclusions: Results support the validity of the GBMMS and its association with breast cancer screening adherence. The GBMMS may be used to further investigate medical mistrust as a barrier to screening for cancers for which ethnic group disparities have been observed.