Support for a Single Underlying Dimension of Self-Reported Health in a Sample of Adults with Low Back Pain in the United States

There is increasing interest in measuring "whole person" health and deriving an overall summary score. Underlying physical and mental health dimensions have been found consistently in prior studies of self-reported health, but it is unclear whether a single underlying health factor is supported across health domains. We examine the dimensionality of nine domains from the Patient-Reported Outcomes Measurement Information System (PROMIS®)-29 + 2 profile measure, the PROMIS social isolation scale, the Personal Wellbeing Index, and the EQ-5D-5L preference score in a sample of 1256 adults with back pain in the United States: mean age was 55 (range 18-94), 52% female, 74% non-Hispanic White, 61% were married or living with a spouse, and the highest level of education completed for 35% of the sample was a high school degree or general education diploma. The sample reported substantially more pain intensity, pain interference, and worse physical function than the U.S. general population. Product-moment correlations among the measures ranged from 0.25 to 0.83 (median correlation = 0.52). A bifactor model showed that a general health factor accounted for most of the covariation among measures, but physical function, pain interference, and pain intensity loaded slightly more on the physical health group factor than on the general health factor. The study provides some support for combining multiple aspects of self-reported health into an overall indicator of whole-person health.