Validation of a standardized question and a numerical rating scale for assessment of patient satisfaction after knee arthroplasty at one and two years.

Authors

Nick D Clement, Donia Karimaghaei, Irrum Afzal, Fares S Haddad, Deiary F Kader

Published in

Bone & joint open. Volume 7. Issue 7. Pages 916-925. Jul 13, 2026. Epub Jul 13, 2026.

Abstract

The aim was to validate the use of a standardized satisfaction question with a numerical rating scale (NRS) response following knee arthroplasty (KA) at one and two years.
A retrospective study was conducted over six years and included 7,644 KAs in 6,690 patients. Patient demographic details, American Society of Anesthesiologists (ASA) grade, and preoperative and postoperative Oxford Knee Scores (OKS), and EQ-5D-3L) scores were obtained from a local arthroplasty register. Patient satisfaction was assessed at one and two years postoperatively using a standardized questionnaire with possible responses ranging from 0 (not satisfied) to 100 (very satisfied) on a NRS.
During the study period, 5,893 and 4,879 KA had completed outcomes at one and two years' follow-up, respectively. The median satisfaction score was 90 (IQR 80 to 100). There were moderate correlations between the postoperative OKS at one year (r = 0.554) and two years (r = 0.441) with satisfaction, supporting construct validity. Responses to the satisfaction question were skewed, with a 34.1% ceiling effect. The test-retest analysis showed an intraclass coefficient of 0.934 (95% CI 0.886 to 0.962) for single measures and 0.966 (95% CI 0.940 to 0.981) for average measures, suggesting good to excellent reliability. Longitudinal agreement between one and two years showed an intraclass coefficient of 0.71 (95% CI 0.68 to 0.74, p < 0.001). Level of satisfaction was not influenced by preoperative variables or had a negligible to weak influence on satisfaction. Suggested thresholds in satisfaction score were very satisfied ≥ 90, satisfied as 80 to 89, neutral 60 to 79, dissatisfied 40 to 59, and very dissatisfied < 40.
The NRS was a valid, reliable, and universally applicable measure of satisfaction following KA, with a smaller ceiling effect than Likert scales. One year appears optimal for assessing satisfaction, as no further improvement occured beyond this, and follow-up rates decline. The defined thresholds will help identify satisfied and unsatisfied patients.

PMID:
42437667
Bibliographic data and abstract were imported from PubMed on 13 Jul 2026.

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