Minimal Clinically Important Difference in Patient-Reported outcome 3 Months After Knee Joint Replacement - Stratified by Preoperative Patient-Reported Outcome Scores.

yuki sagawa, yuta yagi, misaki tamai, yukie shimane, tomoyo tanaka, kazutaka sugimoto
Purpose:

The purpose of this study is to stratify preoperative WOMAC scores to create an MCID for KJR patients.

Methods:

This study was a prospective cohort study. The inclusion criteria were defined as those who underwent initial KJR at our hospital due to osteoarthritis of the knee between January 10 and July 31, 2024. The exclusion criteria were set as follows: 1) those with unanswered or missing preoperative and 3-month postoperative questionnaires; 2) those with visual or cognitive impairment that prevented them from completing the questionnaire. WOMAC was measured preoperatively and both WOMAC and a Global Rating Scale of 7- level (worsened, slightly worsened, no changed, slightly improved, improved, much improved, and very much improved) were measured at 3 months postoperatively. The patients were classified into two groups (Group A and Group B) based on the median preoperative WOMAC score, and the MCID for each group was calculated. For statistical analysis, the Euclidian method using the Receiver Operating Characteristic curve was used to calculate MCID. For anchor grouping purposes, slightly improved or greater was defined as the improved group. No change or lower was defined as no changed group.

Results:

221 subjects (mean ± standard deviation, age: 73.1 ± 8.2, height: 158.8 ± 1.8 cm, weight: 82.1 ± 28.2 kg) were included in the study. The median WOMAC-p was 50 points and the median WOMAC-f was 64 points. The MCID for WOMAC-p was 30 points (Area under the curve (AUC): 0.95) for group A (50 points) and 12.5 points (AUC: 0.72) for group B (≤50 points). The MCID for WOMAC-f was 13.2 (AUC: 0.82) for group A (64 points) and 0.8 (AUC: 0.67) for group B.

Conclusion(s):

If the preoperative WOMAC-p score was less than 50, the MCID was 30. If it was greater than 50, the MCID was 12.5. If the preoperative WOMAC-f score was less than 64, the MCID was 13.2. If the score was 64 or higher, the MCID was 0.8.

Implications:

By establishing reference values that take into account preoperative PRO scores, it will be possible to evaluate treatment outcomes tailored to each patient.

Funding acknowledgements:
nothing
Keywords:
Minimal Clinically Important Difference
The Japanese version of the WOMAC
preoperative WOMAC scores
Primary topic:
Musculoskeletal: lower limb
Second topic:
Orthopaedics
Third topic:
Musculoskeletal
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
The Medical Corporation Sonodakai Ethics Committee.
Provide the ethics approval number:
Approval No. 186
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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