Validation of PROMIS-29 domain scores among adult burn survivors: A National Institute on Disability, Independent Living, and Rehabilitation Research Burn Model System Study

BACKGROUND Patient-reported outcomes are important for understanding recovery after burn injury, benchmarking service delivery and measuring the impact of interventions. Patient-Reported Outcomes Measurement Information System (PROMIS)-29 domains have been validated for use among diverse populations though not among burn survivors. The purpose of this study was to examine validity and reliability of PROMIS-29 scores in this population. METHODS The PROMIS-29 scores of physical function, anxiety, depression, fatigue, sleep disturbance, ability to participate in social roles, and pain interference were evaluated for validity and reliability in adult burn survivors. Unidimensionality, floor and ceiling effects, internal consistency, and reliability were examined. Differential item functioning was used to examine bias with respect to demographic and injury characteristics. Correlations with measures of related constructs (Community Integration Questionnaire, Satisfaction with Life Scale, Post-Traumatic Stress Checklist-Civilian, and Veteran’s Rand-12) and known-group differences were examined. RESULTS Eight hundred and seventy-six burn survivors with moderate to severe injury from 6 months to 20 years postburn provided responses on PROMIS-29 domains. Participants’ ages ranged from 18 years to 93 years at time of assessment; mean years since injury was 3.4. All PROMIS domain scores showed high internal consistency (Cronbach’s α = 0.87–0.97). There was a large ceiling effect on ability to participate in social roles (39.7%) and physical function (43.3%). One-factor confirmatory factor analyses supported unidimensionality (all comparative fit indices >0.95). We found no statistically significant bias (differential item functioning). Reliability was high (>0.9) across trait levels for all domains except sleep, which reached moderate reliability (>0.85). All known-group differences by demographic and clinical characteristics were in the hypothesized direction and magnitude except burn size categories. CONCLUSION The results provide strong evidence for reliability and validity of PROMIS-29 domain scores among adult burn survivors. Reliability of the extreme scores could be increased and the ceiling effects reduced by administering PROMIS-43, which includes six items per domain, or by administering by computerized adaptive testing. LEVEL OF EVIDENCE Diagnostic Test or Criteria, level III.