Abstract
The best tools to assess patient illness understanding are unclear. Here, we examined the assessment tools for illness understanding administered in randomized clinical trials (RCTs) involving patients with advanced cancer, how accuracy of illness understanding was assessed, and each tool's level of accuracy. We conducted a systematic review of Ovid MEDLINE, Ovid EMBASE, and Web of Science from database inception to 28 February 2024. We included all RCTs that reported on illness understanding assessments in cancer patients. The assessment measures were classified into five categories: prognostic awareness, health status, curability, treatment intent, and treatment risks/benefits. We extracted the questions, answers, definitions of accuracy, and accuracy rates of each category. The final sample included 27 articles based on 16 RCTs; five articles (19%) had a Jadad score of ≥3. Among these articles, 10 (37%) assessed prognostic awareness, 4 (15%) assessed health status, 9 (33%) assessed curability, 11 (41%) assessed treatment intent, and 3 (11%) assessed treatment risks/benefits. Only four RCTs examined illness understanding as a primary outcome or communication intervention. We observed significant heterogeneity in the questions, answers, definition of accuracy, and accuracy rate of patients' responses for all themes except for health status. The accuracy rate ranged from 6% to 33% for prognostic awareness, 45% to 59% for health status, 35% to 84% for curability, 26% to 88% for treatment intent, and 17% to 75% for treatment risks/benefits. This study highlights significant variation in current illness understanding assessments and opportunities for standardization to support clinical practice and research.