Development and initial psychometric validation of the Organ Donation Scale for University Students (ODS-US)

Organ shortage remains a major global public health challenge, with persistently low donation rates limiting access to life-saving transplantation. Recent systematic evidence suggests a lack of comprehensive, psychometrically validated instruments for assessing the multidimensional determinants of organ donation among university students, thereby limiting the evaluation of health promotion interventions and public health strategies. To develop and conduct an initial psychometric evaluation of the Organ Donation Scale for University Students (ODS-US), a multidimensional instrument developed for Mexican university students. A methodological study was conducted in two sequential phases comprising instrument development and psychometric evaluation. Following a structured literature search, a two-round Delphi process with expert content validation, and pilot testing, the ODS-US was developed. Psychometric properties were evaluated in a sample of 413 undergraduate students from six higher education institutions in Guerrero, Mexico. Content validity, exploratory and confirmatory factor analyses, internal consistency, and convergent and discriminant validity were assessed. The ODS-US demonstrated strong content validity (overall Aiken's V = 0.891). Exploratory factor analysis supported a six-factor structure explaining 60.3 % of the total variance. Confirmatory factor analysis showed that CFI (0.973) and TLI (0.969) met the predefined criteria for acceptable fit, whereas RMSEA (0.130) and SRMR (0.103) exceeded the predefined threshold of 0.08. The 29-item Likert component demonstrated high internal consistency (Cronbach's α = 0.892; McDonald's ω = 0.939), while the knowledge subscale showed good reliability (KR-20 = 0.725). Composite reliability and average variance extracted provided evidence of convergent validity, whereas HTMT values supported discriminant validity. The ODS-US showed evidence of content validity, internal consistency, and convergent and discriminant validity; however, the mixed findings for model fit indicate that the proposed factor structure requires further evaluation. The instrument may be useful for public health research and the evaluation of health promotion interventions, while further validation in independent samples is needed before drawing stronger conclusions about its structural validity.