Responsiveness of the Patient-Reported Outcomes Measurement Information System (PROMIS), Neck Disability Index (NDI) and Oswestry Disability Index (ODI) instruments in patients with spinal disorders.

BACKGROUND CONTEXT: The Patient-Reported Outcomes Information System (PROMIS) instruments are an important advancement in the use of PROs, but need to be evaluated with longitudinal data to determine whether they are responsive to change in specific clinical populations.

PURPOSE: The purpose of this study was to assess the responsiveness of the PROMIS Physical Function (PF), PROMIS Pain Interference (PI), Neck Disability Index (NDI), and the Oswestry Disability Index (ODI).

STUDY DESIGN/SETTING: This study entailed prospective data collection from consecutive patients aged 18 and older, visiting a university-based orthopaedic spine clinic between October 2013 and January 2017.

PATIENT SAMPLE: A total of 763 participants in the sample had a mean age of 58 (SD = 15) years and the sample was 50.2% male and 92.8% Caucasian.

OUTCOME MEASURES: The PROMIS PF and PROMIS PI Computerized Adaptive Tests along with either the NDI or ODI instruments were administered on tablet computers before clinic visits. Global rating of change questions relating to pain and function levels was also administered.

METHODS: Baseline scores were compared with follow-up scores at four different time-points from 3-months to 6-months and beyond. Patient demographics, mean scores, paired-sample t tests, Standardized Response Mean (SRM), and Effect Size (ES) were analyzed to determine instrument responsiveness. This project was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under award number U01AR067138 and the authors have no conflicts of interest to disclose.

RESULTS: The PROMIS instruments were strongly correlated with each other as well as with the NDI and ODI. Responsiveness was significant on all four instruments at every time-point assessed (paired sample t tests ranged from p < .001 to p = .049). SRM's were large and over 0.94 for every instrument at every time-point. Cohen's d ES were large and over 0.96 for all at all time-points, except for the NDI which had ES ranging from 0.74 to 0.83. This study showed large effect sizes and responsiveness of the PROMIS PF, PROMIS PI, NDI and ODI in a population of orthopaedic patients with spine pathologies.

CONCLUSION: This study demonstrates strong responsiveness of the PROMIS PF and PROMIS PI in a spine clinic population.