Instruments Measuring Autism-Related Knowledge, Attitudes, Perceptions and Behaviours: A Structured Mapping Review with a Targeted COSMIN Appraisal of Measures Evaluated in Health-Professional Populations

Background: Instruments measuring autism-related knowledge, attitudes and self-efficacy are widely used with health professionals, but their measurement properties remain unclear when individual scores are considered separately. Methods: We mapped instruments evaluated in health-professional populations and appraised them using COSMIN, treating each total score, subscale and translation as a separate unit of appraisal. Certainty and recommendation categories were then assigned. Results: Across 126 instrument–property cells for fourteen instruments, the 140 rating codes included eight sufficient, three insufficient, thirty-seven indeterminate and seventy-five not-evaluated codes. All appraised instruments were category B in the primary analysis, indicating that evidence supports neither a positive nor a negative recommendation. A reflective-model sensitivity reading placed the Greek KCAHW in category C. The dominant finding is absence rather than inadequacy: measurement error and responsiveness were examined for none, and cross-cultural validity and test–retest reliability for few. Where a result exists it usually cannot be interpreted, because the dimensionality of the score was never established. Content validity was independently examined for a minority of instruments, addressing expert agreement with answer keys rather than comprehensiveness or comprehensibility. Conclusions: Establishing structural validity in the population of use, and evaluating content validity with intended respondents, would address the principal evidence gaps.