The development of the Clinician-reported Genetic testing Utility InDEx (C-GUIDE): a novel strategy for measuring the clinical utility of genetic testing

Clinical utility describes a genetic test’s value to patients, families, health-care providers, systems, or society. This study aims to define clinical utility from the perspective of clinicians and develop a novel outcome measure that operationalizes this concept. Item selection for the Clinician-reported Genetic testing Utility InDEx (C-GUIDE) was informed by a scoping review of the literature. Item reduction was guided by qualitative and quantitative feedback from semistructured interviews and a cross-sectional survey of genetics and nongenetics specialists. Final item selection, index scoring, and structure were guided by feedback from an expert panel of genetics professionals. A review of 194 publications informed the selection of a preliminary set of 25 items. Feedback from 35 semistructured interviews, 113 surveys, and 11 expert panelists informed the content and wording of C-GUIDE’s final set of 18 items that reflect on the utility of testing related to diagnosis, management, and familial/psychosocial impact. C-GUIDE achieves content and face validity for use in a range of diagnostic genetic testing settings. Work to establish reliability and construct validity is underway. C-GUIDE will be useful in comparative studies to generate policy-relevant evidence pertaining to the clinical utility of genetic testing across a range of settings.