Performance of the shared <scp>decision‐making</scp> process scale for use in evaluation of hereditary cancer genetic testing decisions

This study aimed to evaluate feasibility, acceptability, reliability, and validity of the existing four-item Shared Decision Making (SDM) Process Scale for use in evaluating genetic testing decisions. Patients from a large hereditary cancer genetics practice were invited to participate in a two-part survey after completing pre-test genetic counseling. The online survey included the SDM Process Scale and the SURE scale, a measure of decisional conflict. SDM Process scores were compared to SURE scores to test convergent validity, and respondents were sent a second survey 1 week later to assess retest reliability. The response rate was 65% (n = 259/398) and missing data was low (<1%). SDM scores ranged from zero to four with a mean of 2.3 (SD = 1.1). Retest reliability was good, with intraclass correlation of 0.84, 95% confidence interval (0.79, 0.88). No relationship was found between SDM Process scores and decisional conflict (p = 0.46), likely because 85% of participants reported no decisional conflict. The four-item SDM Process Scale demonstrated feasibility, acceptability, and retest reliability, but not convergent validity with decisional conflict. These findings provide initial evidence for use of this scale to measure patient perceptions of SDM in pre-test counseling for hereditary cancer genetic testing.