Differential item functioning of the Subjective Happiness Scale, Satisfaction with Life Scale, and Recovery Assessment Scale for Black and White persons with schizophrenia spectrum disorders

Objective To detect disparities in health outcomes, measures should demonstrate invariance across groups. Whether responses to recovery-related measures vary by race for psychiatric rehabilitation service recipients is unclear. This study examined the psychometric properties of three recovery-related scales, including the Satisfaction with Life Scale (SWLS), Subjective Happiness Scale (SHS), and Recovery Assessment Scale Short Form (RAS).Methods Using cross-sectional, retrospectively collected data from a mental health center, the authors tested uniform and non-uniform differential item functioning (DIF) by race. Data were available for 599 psychiatric rehabilitation service recipients aged 18 or older, diagnosed with a schizophrenia spectrum disorder (F20–F29), and who identified as non-Hispanic Black (n = 460) or non-Hispanic White (n = 139).Results One SHS item (#4) showed uniform DIF (R2 = 0.0041, p < .01). One RAS item showed non-uniform DIF (#4) (R2 = 0.02, p < .001). DIF was undetected in the SWLS.Conclusion and implications for practice This was one of the first studies to test for DIF in the SWLS, RAS, and SHS among a sample of psychiatric rehabilitation service recipients. DIF was largely unobserved in each scale. Future research should explore DIF in more racially and ethnically diverse psychiatric rehabilitation service recipients.Impact and implications Cultural factors may influence how people receiving psychiatric rehabilitation services respond to measures of mental health recovery and related concepts. This study found that common measures of recovery, happiness, and well-being performed similarly for Black and White service recipients with psychotic disorders. Additional research is warranted to ensure that measures of personal recovery perform equitably across cultures.