A Comparison of the Psychometric Properties of PROMIS Computer Adaptive Tests and Short Forms Vs Legacy...

Traditionally used PROMs evaluating total knee arthroplasty (TKA) have large measurement error and limited measurement range. Patient-Reported Outcomes Measurement Information System (PROMIS) has theoretical possibilities to overcome these limitations. This study evaluates the psychometric properties of PROMIS vs legacy PROMs in TKA patients.

210 patients were included from 3 orthopaedic departments. Patients completed a questionnaire twice in a 2-week interval, including 2 PROMIS Computer Adaptive Tests (CATs), assessing Physical Function (PF) and Pain Interference (PI), 5 PROMIS short forms (SF) (PF-SF8b, PF-SF10a, PF-SF-20a, PI-SF8a, PI-1a) and 6 legacy PROMs (KOOS, KOOS-PS, WOMAC, OKS, 2 numeric rating scales). Reliability, measurement precision, smallest detectable change (SDC), construct validity, burden and extreme scores were investigated.

All PROMIS CATs, SFs, and legacy PROMs showed adequate test-retest reliability. PROMIS CATs and SFs showed sufficient construct validity. Regarding PF, the SDC varied between 2.8-6.1 for PROMIS and 7.3-19.9 for legacy PROMs. PROMIS CAT and SFs showed no extreme scores using 5-20 items, legacy PROMs showed 1.2%-3% extreme scores using 7-17 items. Concerning pain, the SDC varied between 2.8-6.1 for PROMIS and 22.5-35.4 for legacy PROMs. PROMIS showed 0%-9.5% extreme scores using 5-8 items and legacy PROMs 8.7%-19.1% using 1-9 items.

PROMIS CAT and SFs seem more efficient assessing PF in TKA compared to legacy PROMs by offering reduced burden and measurement error, and minimizing extreme scores. PROMIS PI-8a seems most suitable in measuring pain without extreme scores. This study supports a shift from legacy PROMs toward PROMIS in TKA patients.