Development and Validation of a Patient-Centered Scale to Evaluate Decision Aid Usability and Information Overload.

INTRODUCTION: Decision aids aim to improve the quality of and satisfaction with decision making. Few scales exist that directly evaluate decision aids from the patient's perspective, particularly with respect to information overload. METHODS: We developed a Decision Aid Evaluation Scale with domains assessing acceptability, satisfaction, cognitive load, and helpfulness for decision making. Cognitive interviews and iterative testing were performed. Convergent and discriminant construct validity were assessed by comparing the novel scale with domains from the validated Decisional Conflict Scale (DCS; values clarity, uncertainty, feeling informed subscales). Internal consistency was measured using Cronbach's alpha. The final scale consisted of Likert-type scale items assessing information amount, values clarity, ease of use, cognitive effort required, nervousness, and overall helpfulness. Participants (any sex or gender, aged 40-60 y) completed the scale after viewing a cancer screening decision aid within a hypothetical screening decision scenario. RESULTS: We surveyed 1,249 participants; 778 completed the Decision Aid Evaluation Scale. As hypothesized, a larger proportion of participants who reported low cognitive load had higher DCS values clarity subscale scores than those with high cognitive load (P = 0.003). Participants who found the decision aid helpful had significantly higher DCS values clarity (P < 0.001), informed (P = 0.004), and certainty subscale scores (P < 0.001). Scores on the acceptability questions were higher among those who found the decision aid helpful (P < 0.001), except for questions related to "length," "relatability of photo," and "photo helped make decision." Participants reporting nervousness had lower DCS certainty subscale scores (P < 0.001). Cronbach's alpha for the acceptability and satisfaction domains were 0.74 and 0.75, respectively, indicating internal consistency. CONCLUSIONS: We developed a patient-centered scale that captures users' perceptions of decision aid usability and information overload. The scale demonstrated acceptable construct validity and internal consistency, supporting its use in evaluating decision aids from the patient perspective.