Content-Related Validity of the Rand-36 Composite Scores with Other Patient-Reported Outcome Scales Among National Health and Wellness Survey Respondents in the United States, Japan, and 5 European Countries

OBJECTIVES: The objective of this research was to evaluate the association between the RAND-36 measure of health-related quality of life and other validated patient-reported outcome scales (PROs).

METHODS: The National Health and Wellness Survey (NHWS) collected data in the United States in 2023, Japan (JP) in 2023, and five European countries (5EU: Germany, Spain, France, Italy, United Kingdom) in 2022. NHWS is a web-based survey that is nationally representative of each country. This research focused on three composite scores from the RAND-36: global (GHC), mental (MHC), and physical (PHC) health composite scores. PROs on quality of life and condition severity included: EQ5D index & VAS, Work Productivity and Activity Impairment (WPAI), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Migraine Disability Assessment (MIDAS), Insomnia Severity Index (ISI), and Dermatology Life Quality Index (DLQI). Descriptive statistics were used to describe respondent characteristics and Pearson’s correlations were used to describe the association between the RAND-36 measures and the other listed PROs.

RESULTS: There were n=75,007 respondents in the US, n=30,013 in JP, and n=62,005 in 5EU. The mean respondent ages in the US (48), JP (53), and 5EU (50) were similar. For each region, the EQ5D index and VAS, overall work impairment, and activity impairment were all highly correlated (|r_p|>.50) with each composite score. PHQ-9 and GAD-7 scores were highly correlated with GHC and MHC in all regions. MIDAS, ISI, and DLQI scores were moderately correlated (|r_p|>.30) with GHC for all regions. All correlations between the RAND-36 composite scores and the other PROs were statistically significant (all p<.001).

CONCLUSIONS: The three RAND-36 composite scores were comparable to other validated PROs. The strong correlations between the scales of interested confirmed the content validity of the RAND-36 scale.