Do Patient-Reported Outcomes Reflect Objective Measures of Function? Implications for Total Knee Arthroplasty

Area of Science:

• Orthopedics
• Rheumatology
• Health Outcomes Research

Background:

• Patient-reported outcomes (PROs) are crucial for assessing knee osteoarthritis (OA) and total knee arthroplasty (TKA) outcomes in research and clinical practice.
• The reliability of PROs as a reflection of objective physical function needs thorough investigation.

Purpose of the Study:

• To determine the correlation between commonly used PROs and standardized functional tests (SFTs) in patients with knee OA and TKA.
• To assess if PROs can serve as a proxy for objective physical function measurements.

Main Methods:

• Utilized data from the Osteoarthritis Initiative, a 10-year observational study.
• Analyzed two cohorts: native knee OA (n=4,687) and TKA recipients (n=281).
• Correlated PROs (WOMAC, KOOS, SF-12, ICOAP) with SFTs (walk pace, chair stand pace) using repeated measures correlation.

Main Results:

• A weak correlation was observed between PROs and SFTs in both native knee OA and TKA cohorts.
• Correlation coefficients (r_rm) ranged from 0.00 to 0.30, indicating limited agreement between subjective reports and objective tests.
• P values were generally < .05, but the low correlation magnitude limits the clinical significance.

Conclusions:

• PROs and SFTs are not strongly associated in patients with knee OA or following TKA.
• PROs should not be used as a sole proxy for evaluating physical function.
• A combined approach utilizing both PROs and SFTs is recommended for a comprehensive outcome assessment.