Assessing the Structural Validity and Measurement Invariance of the Whole Person Health Index

Area of Science:

• Health Measurement
• Psychometrics
• Holistic Health Assessment

Background:

• The concept of "whole person health" necessitates comprehensive measurement tools.
• The Whole Person Health Index (WPHI) is a nine-item instrument designed to capture various dimensions of health and well-being.
• Initial evaluations suggest the WPHI holds promise for clinical and population-level assessments.

Purpose of the Study:

• To conduct an exploratory analysis of the psychometric properties of the Whole Person Health Index (WPHI).
• To evaluate the factor structure and measurement performance of the WPHI in a diverse adult population.

Main Methods:

• The WPHI was administered as part of the National Center for Health Statistics Research and Development Survey (RANDS 11).
• Descriptive statistics and psychometric analyses, including factor and bifactor analyses, were employed.
• Analyses explored the WPHI's functioning overall and across different demographic subgroups.

Main Results:

• The WPHI exhibited strong internal consistency and favorable measurement characteristics.
• Factor analyses indicated a dominant general factor underlying WPHI responses, though strict single-factor model fit benchmarks were not fully met.
• Differential item functioning was observed for self-rated health by age, but not for other items or subgroups.

Conclusions:

• The WPHI's subjective ratings reflect a cohesive construct, supporting its use as a broad measure of health aligned with whole person health principles.
• Potential differences in item interpretation across age groups warrant caution when comparing WPHI scores between these demographics.