Examining the Factor Structure of Objective Health Literacy and Numeracy Scales: Large-Scale Cross-Sectional Study.

Area of Science:

• Health literacy research
• Psychometric analysis
• Health behavior studies

Background:

• Health literacy and numeracy scales are classified as objective (performance-based) or subjective (self-reported).
• Objective and subjective scales may not always align and can measure different underlying constructs.
• The increasing number of objective health literacy measures raises questions about the optimal number of latent factors to assume.

Purpose of the Study:

• To investigate the psychometric properties and factor structure of objective health literacy items.
• To determine the correlation between objective health literacy aspects and subjective measures.
• To explore the relationship between objective health literacy and health behaviors/lifestyles.

Main Methods:

• Administered 5 objective scales (72 items) to 16,097 Japanese adults.
• Scales assessed numeracy, comprehension, and application of health information, including disease-specific contexts.
• Utilized exploratory factor analysis to identify latent constructs and tested correlations with subjective health literacy and behaviors.

Main Results:

• Exploratory factor analysis revealed 3 latent factors: conceptual knowledge, numeracy, and synthesis.
• Disease-specific contextualization did not significantly alter the numeracy factor.
• Factors showed moderate correlations with subjective health literacy and small positive correlations with healthy diet and lower substance use.

Conclusions:

• Objective health literacy scales encompass at least three distinct latent constructs: conceptual knowledge, numeracy, and synthesis.
• Disease specificity is not a psychometrically significant feature in objective health literacy measures.
• Objective and subjective health literacy should be considered independent constructs due to their limited correlations.