TORONTO – A high level of pain catastrophizing prior to scheduled knee arthroplasty is not, as previously thought, a harbinger of poor outcomes, and affected patients don’t benefit from cognitive-behavioral therapy–based training in pain coping skills, Daniel L. Riddle, PhD, reported at the OARSI 2019 World Congress.
“The take-home message for us is knee arthroplasty is incredibly effective and there really is no reason to do pain coping skills training in these high–pain catastrophizing patients because the great majority of them have such good outcomes,” said Dr. Riddle, professor of physical therapy at Virginia Commonwealth University, Richmond.
“The other clear message from our trial is that, when you have pain-catastrophizing patients and you lower their pain, their catastrophizing is also lowered. So pain catastrophizing is clearly a response to pain and not a personality trait per se,” he said at the meeting sponsored by the Osteoarthritis Research Society International.
He presented the results of a 402-patient, randomized, three-arm, single-blind trial conducted at five U.S. medical centers. All participants were scheduled for knee arthroplasty for osteoarthritis, and all had moderate- to high-level pain catastrophizing as reflected in the group’s average Pain Catastrophizing Score of 30. They were assigned to an arthritis education active control group, usual care, or an intervention developed specifically for this study: a cognitive-behavioral therapy–based training program for pain coping skills. Similar pain coping skills training interventions have been shown to be beneficial in patients with medically treated knee OA but hadn’t previously been evaluated in surgically treated patients. The primary study endpoint was change in the Western Ontario and McMaster Universities Osteoarthritis Index () Pain Scale at 2, 6, and 12 months after surgery.
The improvement in WOMAC pain in the three study arms was virtually superimposable, going from an average pain score of about 12 preoperatively to 2 postoperatively.
“This was a clear no-effect trial,” Dr. Riddle observed. “These are patients we thought to be at increased risk for poor outcome, but indeed they’re not.”
Pain Catastrophizing Scores improved from 30 preoperatively to roughly 7 at 1 year. “We’ve never seen pain catastrophizing improvements of this magnitude,” the researcher commented.
The study participants typically had a large number of chronically painful areas, but only minimal change in pain scores occurred except in the surgically treated knee.
Of note, even with the impressively large improvements in knee pain, function, and other secondary endpoints in the study group as a whole, roughly 20% of study participants experienced essentially no improvement in their function-limiting knee pain during the first year after arthroplasty. These nonresponders were spread equally across all three study arms. Further research will be needed to develop interventions to help this challenging patient subgroup.
The pain coping skills training consisted of 8 weekly sessions, each an hour long, which began prior to surgery and continued afterward. The intervention was delivered by physical therapists who had been trained by pain psychologists with expertise in cognitive-behavioral therapy. The intervention was delivered by telephone and in face-to-face sessions. The trainers were tracked over the course of the study to make sure that the structured intervention was delivered as planned.
Dr. Riddle reported having no financial conflicts regarding the National Institutes of Health-funded study, the full details of which have been published ().