Low-Dose Radiation Therapy for Knee, Hand Osteoarthritis Questioned

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There is insufficient evidence to support long-term effects on pain and functioning of low-dose radiation therapy for hand and knee osteoarthritis, say researchers writing in The Lancet Rheumatology.

A clear need exists to improve management of osteoarthritis as no effective disease-modifying treatments are available. Studies have suggested that synovitis in knee and hand osteoarthritis is associated with pain and structural damage, and that low-dose radiation therapy can have anti-inflammatory effects. Despite the absence of studies with acceptable quality to support the use of low-dose radiation therapy in clinical practice, the therapy is a commonly used treatment method for benign disorders, including osteoarthritis, in some countries. Two randomized-controlled trials showed that low-dose radiation therapy for knee and hand osteoarthritis had no significant effects at one, two, and three months after the intervention on either symptoms or inflammation, assessed by magnetic resonance imaging and ultrasound.

“The aim of the current study was to assess the long-term efficacy of low-dose radiation therapy on symptoms in patients with knee and hand osteoarthritis,” wrote the authors, led by Cornelia H M van den Ende, Ph.D., of Sint Maartenskliniek Nijmegen in The Netherlands. “Here we report the proportion of participants who responded at six months and 12 months, and other clinical outcomes of pain, functioning, and patients' global assessment of their symptoms.”

The two randomized-controlled trials were undertaken in parallel, with one recruiting 55 patients with knee osteoarthrosis and the other recruiting 56 patients with hand osteoarthritis. Patients had osteoarthritis according to American College of Rheumatology criteria and had a pain score of five or more on a 0–10 scale for at least 15 of the past 30 days. In each study, patients were randomly assigned to low-dose radiation therapy or placebo. Patients completed questionnaires (numeric rating scale of patients' global assessment and validated measures for pain and functioning) at baseline and at one, two, three, six, and 12 months after starting treatment. The primary outcome was the proportion of participants who responded according to the Outcome Measures in Rheumatology Osteoarthritis Research Society International (OMERACT-OARSI) responder criteria.

No significant differences at six or 12 months was found in the proportion of participants who had a response for both groups. In the knee osteoarthritis group, at six months, 41 percent who received low-dose radiation therapy had a response versus 35 percent in the placebo group (difference in proportion 7 percent [95% CI −20 to 33]; odds ratio [OR] 1.34 [95% CI 0.41 to 4.42]); and at 12 months, the response rates were 52 percent versus 44 percent (difference in proportion 8 percent [–19 to 35]; OR 1.41 [0.45 to 4.48]). In the hand osteoarthritis group, at six months, the respective response rates were 28 percent versus 31 percent  (difference in proportion 12 percent [–38 to 13]; OR 0·57 [0.18 to 1.81]); and at 12 months, the response rates were 31 percent versus 27 percent, respectively, (difference in proportion 4 percent [–20 to 29]; OR 1·23 [0.37 to 4.12]).

No difference was found between groups in other clinical outcomes at six or 12 months. Three participants with knee osteoarthritis in the placebo group and two participants with hand osteoarthritis in the low-dose radiation therapy group had serious adverse effects, none of which were considered intervention related.

“Considering that the current practice of low-dose radiation therapy is not evidence based and could harm patients, we feel that our results should be considered in clinical practice,” the authors wrote.

REFERENCE

Cornelia H M van den Ende, Michiel J M Minten, Mathilde M Leseman-Hoogenboom, et al. “Long-term efficacy of low-dose radiation therapy on symptoms in patients with knee and hand osteoarthritis: follow-up results of two parallel randomised, sham-controlled trials.”The Lancet Rheumatology. November 29, 2019. DOI: https://doi.org/10.1016/S2665-9913(19)30096-7