The development and validation of a questionnaire to assess relative energy deficiency in sport (RED-S) knowledge.

Objectives: The aim of this study was to develop and validate a questionnaire assessing knowledge of signs and symptoms of relative energy deficiency in sport among healthcareprofessionals and physically active individuals.

Design: Cross-sectional study.

Methods: The questionnaire was created in two phases: 1)Item development was established through a literature review, expert review (n = 4), and pre-testing among healthcare professionals, dietetic students, and the general population (n = 35). 2) Validity (item analysis, construct validity) and internal reliability were assessed by administrating the questionnaire to healthcare professionals (n = 97) and physically active individuals who engaged in moderate to intense physical activity (n=77). The questionnaire was re-administered in a subset of the same groups (n = 88) for test-retest reliability.

Results: The expert responses showed >80% acceptability and pretesting through interviews indicated good content and face validity. Item response analysis resulted in removal of 6 items due to low discrimination ability. Significantly higher knowledge scores in health professionals compared with non-health professionals (mean difference (95% CI) = 2.8 (1.9, 3.7)) confirmed construct validity. Internal consistency, assessed using Cronbach's alpha (α = 0.79), and test-retest reliability using intra-class correlation coefficients (intra-class correlation coefficients = 0.80; Spearman's correlation = 0.84, p < 0.001) were good. The final questionnaire had 18 items assessing knowledge of signs and symptoms of Relative Energy Deficiency in Sport.

Conclusions: The questionnaire provides a valid and reliable tool to assess knowledge of signs and symptoms of Relative Energy Deficiency in Sport among health professionals and physically active individuals, which could guide future education requirements by assessing current knowledge.