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Fibromyalgia survey scores predictive of poor outcomes in THA, TKA
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Patients with high pain scores on fibromyalgia surveys had poorer outcomes after total hip or knee arthroplasty, according to researchers from the University of Michigan Health System.
A battery of questionnaires was administered preoperatively to 665 participants scheduled to undergo total hip arthroplasty (THA) or total knee arthroplasty (TKA), 464 of whom completed 6-month follow-up postoperatively.
The surveys included the Widespread Pain Index (WPI) calculated using the Michigan Body Map and the Symptom Severity Scale (SSS). Patients were considered fibromyalgia (FM)-positive in the presence of a WPI score of 7 or greater and a SSS score of 5 or greater, or a WPI score between 3 and 6 with a SSS score of 9 or greater.
Knee and hip involvement were assessed using WOMAC scores. Pain was assessed with the Brief Pain Inventory (BPI) and PainDETECT, a nine-item screening tool designed to detect neuropathic pain. Other tests included the Hospital Anxiety and Depressions Scale (HADS) and a subscale of the Coping Strategies Questionnaire-Catastrophizing related to pain.
Patients were excluded in the presence of additional arthroplasty, hardware fracture, revision surgery, postoperative joint infection that required drainage or any other significant surgery.
The primary outcome measure was the change in knee and hip pain 6 months following surgery. Secondary outcomes followed the change in composite BPI and Patient Global Assessment of Change (PGIC).
Data were analyzed both with the inclusion and exclusion of patients who met criteria for FM. In the final model, patients were grouped into a low FM score tier, a moderate FM score tier and a high FM score group.
After analysis, a higher FM survey score was predictive of poorer arthroplasty outcomes, according to the researchers. For each one-point increase in in FM score, the PGIC increased by 17.8%. Multivariate models showed the FM score was also predictive of WOMAC and BPI.
The FM and baseline WOMAC scores were predictive in 73 patients who failed to meet 50% improvement in WOMAC after surgery, particularly after THA. For each one-point increase in FM score, patients reported a 0.19-point drop in improvement on the 11-point pain scale, and the odds of failure to meet 50% improvement increased by 30% for each one-point increase in FM score. The overall pain improvement of 50% was not met by 37.7% of patients.
No association was seen with any measures of anxiety, depression, catastrophizing or neuropathic pain, according to the researchers.
A limitation of the study was that the patients lost to follow-up tended to have higher pain scores, which may have impacted the results. - by Shirley Pulawski
Disclosures: Brummett reports he has received research funding from Neuros Medical. Please see the full study for a list of all other authors’ relevant financial disclosures.
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