Testing Gender and Longitudinal Measurement Invariance of the SF-36 in American Indian Older Adults: The Strong Heart Study

Information about the equality of psychometric properties of the medical outcomes study (MOS) Short Form-36 (SF-36), a health status measure, across gender and across the lifespan for American Indian adults is lacking. We tested measurement invariance (configural, metric, scalar invariance) of the physical and mental components between gender and over time in a sample of 2,709 (1,054 men, 1,654 women) American Indian older adults at three time points, and across a 6-year time frame. Measurement invariance of a 2-factor higher-order model was demonstrated between gender at each time point. Tests of longitudinal invariance indicated longitudinal measurement invariance over time. Multiple-group latent means analysis indicated men had significantly higher physical and mental component latent means compared to women at each time point, and longitudinal latent means analysis found physical and mental component latent means decreased over time. The 2-factor higher-order model SF-36 is valid for American Indian older adults over a 6-year time frame. Public Significance Statement The medical outcomes study (MOS) Short Form-36 (SF-36) is a valid assessment for American Indian older adults. Men had significantly higher physical and mental scores compared to women, and physical and mental components scores decreased over time in the total sample.