For patients with chronic knee pain, a new study has found that treatment by cooled radiofrequency ablation (CRFA) provides significant pain relief and reduces disability.
In this retrospective study, led by Yashar Eshraghi, MD, the medical director of pain research at Ochsner Health and a clinical assistant professor at the Louisiana State University School of Medicine, both in New Orleans, the investigators reviewed 219 patients who had received CRFA therapy of the genicular nerves at a multiple-site pain practice, between December 2017 and September 2019. The study was presented at the 2020 annual pain medicine meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 829).
The primary outcome was improvement in Pain Disability Index (PDI) scores. “The PDI score is designed to measure the degree to which aspects of a patient’s life are disrupted by chronic pain and the overall impact of pain in a patient’s life,” said first author Roshina Khan, MD, an anesthesiology resident at the University of Mississippi Medical Center, in Oxford.
Following genicular nerve block and CRFA, the median PDI score fell from 38.7 to 26.5. Scores decreased in 67.38% of patients, 27.9% had no change, and 4.81% saw an increase (95% CI, –11 to –7; P<0.001).
After genicular nerve block and CRFA, the mean numerical pain rating score decreased from 6.98 to 4.18 (95% CI, –3 to –2; P<0.001). The numerical pain rating score is a unidimensional measure of pain intensity in adults. The largest group of patients, 49%, saw a reduction in pain rating of 2.25 points; 17.3% had a reduction of 0.75 points; and 12.5% had a reduction of 3.75 points.
Among the 62.5% of patients who were taking opioids, the morphine equivalent dose did not change for 80.77%. It decreased for 13.46% and rose for 5.77%.
“This retrospective analysis confirms the results of previous trials on the effectiveness of genicular cooled radiofrequency ablation to provide long-term relief and improvement in quality of life for patients with chronic knee pain,” Khan said. “Providers should seriously consider the utility of CRFA as a reliable treatment option for chronic knee pain.”
“While other studies have assessed pain scores, these scores can be very subjective and don’t reflect how this pain actually affects a patient’s daily life,” Khan noted. “By focusing on PDI score as a primary outcome, we were able to assess the effectiveness of CRFA in a context that is more applicable to the patient’s quality of life.”
Lynn R. Webster, MD, the vice president of scientific affairs at PRA Health Sciences, in Salt Lake City, and a member of the Pain Medicine News editorial advisory board, voiced several concerns about the poster. “The authors do not state when the Pain Disability Index scores were obtained. This raises the question about the duration of the treatment’s effect,” he said.
“It is curious that [the authors] showed a statistical reduction in the PDI but did not show a reduction in the amount of opioids. This raises questions about the clinical meaningfulness of the differences in PDI,” Webster said. A reduction in PDI after treatment should have been accompanied also by a reduction in opioids, but it wasn’t, he said.
In addition, regarding the decrease in the main pain score, Webster noted that the poster contained no information on whether that reduction persisted.
Webster also questioned the finding that a majority of patients reported an improvement in functionality. “A study by Beemester et al (Health Qual Life Outcomes 2018;16[1]:182) suggests that a decrease in the PDI should be greater than 15 to be meaningful for patients with a baseline score between 28 and 42. The baseline for this study was 38.7, which suggests the results may not be meaningful.
“It is important that research is conducted to determine efficacy and safety of all interventions,” Webster said. “The authors should be recognized for their contribution to the literature and, hopefully, they will continue to assess where this technology is worth the cost and risks.”
—David C. Holzman