Purpose: To evaluate the validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) physical function measures in a diverse, population-based cancer sample.
Methods: Cancer patients 6-13 months post-diagnosis (n = 4840) were recruited for the Measuring Your Health study. Participants were diagnosed between 2010 and 2013 with non-Hodgkin lymphoma or cancers of the colorectum, lung, breast, uterus, cervix, or prostate. Four PROMIS physical function short forms (4a, 6b, 10a, and 16) were evaluated for validity and reliability across age and race-ethnicity groups. Covariates included gender, marital status, education level, cancer site and stage, comorbidities, and functional status.
Results: PROMIS physical function short forms showed high internal consistency (Cronbach's α = 0.92-0.96), convergent validity (fatigue, pain interference, FACT physical well-being all r ≥ 0.68), and discriminant validity (unrelated domains all r ≤ 0.3) across survey short forms, age, and race-ethnicity. Known-group differences by demographic, clinical, and functional characteristics performed as hypothesized. Ceiling effects for higher-functioning individuals were identified on most forms.
Conclusions: This study provides strong evidence that PROMIS physical function measures are valid and reliable in multiple race-ethnicity and age groups. Researchers selecting specific PROMIS short forms should consider the degree of functional disability in their patient population to ensure that length and content are tailored to limit response burden.
Keywords: Oncology; Patient-reported outcomes; Physical function; Validation studies.