Adapt and test a measure of knowledge for caregivers of children with attention-deficit/hyperactivity disorder (ADHD) and evaluate the impact of the information component of a decision aid (DA) on participant knowledge.

A set of seven knowledge items were created based on prior knowledge measures and clinical guidelines. As part of a larger cross-sectional survey study of caregivers of children diagnosed with ADHD, caregivers were randomized to one of two arms: 1) a DA arm, where participants reviewed the information component of the Cincinnati Children’s Hospital’s DA, and 2) a control arm, where participants were not shown a DA. All participants completed the seven knowledge items. Knowledge items were assessed for difficulty, quality of distractors, acceptability, and redundancy. Total knowledge scores (0–100) for the DA and control arm were compared.

Caregivers were assigned to the DA arm (n = 243) or the control arm (n = 260). All 7 knowledge items were retained as no items were too difficult or too easy, all response options were used, there were little missing data, and no items were redundant. The overall knowledge score was normally distributed, and almost covered the full range of scores (5–100). Those who received the DA component had higher knowledge scores (M = 68, SD = 23) than those who did not receive the DA component (M = 60, SD = 19, P < .01, d = 0.4).

The Caregiver ADHD Knowledge (CAKe) measure was acceptable and demonstrated construct validity as those who were assigned to review the DA component demonstrated greater knowledge than those who were not assigned to review the DA component.