Cross-national validation of digital health engagement scales: evidence from 30 countries

Introduction Reliable cross-national measurement of digital health engagement is essential for understanding how populations use online health information and for monitoring digital health inequalities. Yet standardized and psychometrically validated tools suitable for international surveys remain scarce. Methods Using representative data from the International Social Survey Programme (ISSP) Health and Health Care II module (2021; N = 40,226; 30 countries), this study evaluated two newly developed instruments: (1) the General Online Health Information Engagement (GOHIE) scale, assessing the behavioral frequency and breadth of online health information seeking, and (2) the Digital Health Usefulness (DHUS) scale, capturing perceived usefulness of online health information. Reliability and construct validity were examined using item discrimination, nonlinear reliability estimation, and confirmatory factor analysis. Cross-national comparability was assessed using Bayesian Approximate Measurement Invariance (BAMI), which allows small probabilistic deviations in parameters across countries. Results Both scales showed satisfactory internal consistency ( ω = 0.70–0.90) and largely unidimensional structures in most countries. DHUS achieved stable approximate measurement invariance across national contexts, whereas GOHIE showed weaker item discrimination and greater contextual variability, particularly for the general information-seeking item and in countries with differing digital infrastructures or translation contexts. Conclusion DHUS provides a robust cross-national measure of attitudinal aspects of digital health engagement, while GOHIE highlights the context-sensitive nature of behavioral online health information seeking and points to directions for future refinement. Cross-national analyses should examine country-specific parameters and apply approximate or partial invariance frameworks. These validated indicators establish a methodological foundation for monitoring digital health engagement and advancing equitable, evidence-based public health communication.