Demographics are no clinically relevant predictors of patient-reported knee osteoarthritis symptoms - Comprehensive multivariate analysis.

Aims & objectives: In clinical practice, arthroplasties are predominantly indicated by clinical and radiological assessment of osteoarthritis. Pain and function are individually considered, but a comprehensive analysis of differences in symptom reporting by pre-operative factors is lacking. In the present study, we determined differences in patient reported outcome measures between demographic groups among patients admitted to total knee arthroplasty. Materials & methods: Between 2010 and 2019, we collected pre-operative Oxford Knee Scores, Western Ontario and McMaster University Osteoarthritis Index, quality of life in 2555 patients undergoing primary, osteoarthritis-indicated total knee arthroplasty at Patients were categorized by sex, age (<70, 70-80, >80 years), body mass index (BMI <25, 25-30, 30-35, >35 kg/m2), American Society of Anesthesiologists -classification (ASA 1, 2, ≥3) and Charnley score (A, B1, B2, C). Symptom scores (median, IQR) were compared using bivariate and multivariate methods. Results: The cohort was 60% female, 70.0 years old (69.4-70.1), and BMI was 28.9 kg/m2 (29.6-30.0). As compared to bivariate analyses, between-group differences in multivariate analyses were consistently smaller. BMI and sex remain significant predictors after adjustment for age, ASA, and Charnley. Age, ASA, and Charnley were no independent predictors of symptom scores. A group of patients (30%) reported no physical dysfunction, and less symptom severity in pain and stiffness. Conclusion: This study is the first to show that differences in symptom reporting between demographic groups are partly colinear, and are negligible for prediction of symptoms. Lastly, for a significant proportion of patients, patient-reported outcome measures do not adequately present disease severity.