Low-dose radiotherapy for painful osteoarthritis of the elderly: A multicenter analysis of 970 patients with 1185 treated sites

Purpose Painful osteoarthritis is common in elderly patients, and low-dose radiotherapy has been demonstrated to provide effective symptomatic treatment. We examined the analgesic effects of low-dose radiotherapy for osteoarthritis in the elderly aiming to reveal potential differences in the response rates relating to increasing age. Methods A retrospective analysis was performed at two university hospitals including elderly patients (>= 65 years) undergoing radiotherapy for osteoarthritis between 2008 and 2020. Pain intensity and response were quantified using the numerical rating scale (NRS) and the Pannewitz score. Age groups were defined for young old (65-74 years), older old (75-84 years), and oldest old patients (>= 85 years). Results In all, 970 patients with 1185 treated sites and a median age of 76 years were analyzed. Mean NRS was 66 at baseline (t0), 53 after radiotherapy (t1), and 44 at first follow-up (t2) (p < 0.001 for t0-t1, t1-t2, and t0-t2). At t1, 1.5% exhibited a Pannewitz score of 0 (no pain), 58.5% of 1-2 (less pain), 36.1% of 3 (equal pain), and 3.9% of 4 (worse pain), while at t2, pain response shifted towards 6.9% (0), 58.6% (1-2), 28.1% (3), and 6.3% (4). Pain response did not differ between age groups at t1 (p = 0.172) or t2 (p = 0.684). In addition, pain response after re-irradiation (n = 384 sites) was 61.0% and was comparable between age groups (p = 0.535). Conclusion Low-dose radiotherapy results in pain reduction in about two-thirds of treated sites with no difference relating to increasing age, showing that radiotherapy is an effective analgesic treatment for osteoarthritis even at advanced ages.