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Willingness to go through surgery again validated the WOMAC clinically important difference from THR/TKR surgery
Bert M Chesworth1, Nizar N Mahomed, Robert B Bourne
1School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, Elborn College, 1201 Western Road, London, Ontario, Canada. bcheswor@uwo.ca
Journal of Clinical Epidemiology
|August 9, 2008
Summary
The study determined the clinically important difference (CID) for total hip replacement (THR) and total knee replacement (TKR) using the WOMAC index. A "good deal better" outcome is a valid threshold for positive CID, negatively impacted by complications.
Area of Science:
- Orthopedic Surgery
- Rheumatology
- Health Outcomes Research
Background:
- Total hip replacement (THR) and total knee replacement (TKR) are common procedures for osteoarthritis.
- Defining a clinically important difference (CID) is crucial for interpreting patient outcomes.
- The Western Ontario McMaster University (WOMAC) osteoarthritis index is a widely used patient-reported outcome measure.
Purpose of the Study:
- To establish the clinically important difference (CID) for pain and function following primary THR and TKR.
- To validate the CID using patient-reported transition ratings and willingness to undergo surgery again.
- To explore factors influencing the achievement of a positive CID.
Main Methods:
- WOMAC scores were collected pre-operatively and one year post-operatively in 2,709 patients.
- Patient-reported transition ratings on a 15-point scale defined a positive CID as 'a good deal better'.
- Receiver operating characteristic (ROC) curves analyzed WOMAC change scores against transition ratings and willingness to repeat surgery.
Main Results:
- For THR, positive CIDs were 41/100 for pain and 34/100 for function.
- For TKR, positive CIDs were 36/100 for pain and 33/100 for function.
- Postoperative complications were found to decrease the likelihood of achieving a positive CID.
Conclusions:
- An improvement of 'a good deal better' serves as an appropriate threshold for positive CID in THR and TKR.
- Achieving a positive CID is inversely related to the occurrence of postoperative complications.
- These findings aid in the interpretation of WOMAC scores in joint replacement outcomes.
