Development and content validation of the Clinician-reported Genetic testing Utility InDEx for genomic newborn screening (C-GUIDE NBS)

PURPOSE: Genomic newborn screening (gNBS) is emerging worldwide. Evidence of clinical utility, acceptability, and performance is required to guide policy and funding decisions. We aimed to develop a tool called C-GUIDE NBS, adapted from the Clinician-reported Genetic testing Utility InDEx (C-GUIDE), to quantify the clinical utility of gNBS for diagnostic testing. METHODS: We drafted an initial version of the tool by identifying relevant domains and modifying existing C-GUIDE items. Interviews were conducted with clinicians involved in gNBS to assess item relevance, comprehensibility, and comprehensiveness. We quantified the number of items that clinicians accepted, modified, or rejected and synthesized qualitative feedback to inform a revised version. These participants also completed content validity questionnaires to rate the relevance and clarity of each item using a 4-point Likert scale. The relevance and clarity scores were calculated between 0 and 1. Then, we refined C-GUIDE NBS using a 3-step international Delphi consensus process. RESULTS: In the cognitive interviews, participants (N = 22) indicated that 8 of the preliminary 11 items were acceptable for inclusion as is; 2 items required modifications, and 1 was rejected. On the revised 10-item tool, item relevance and clarity scores