Radiosynovectomy using yttrium-90, phosphorus-32 or rhenium-188 radiocolloids versus corticoid instillation for rheumatoid arthritis of the knee.
BACKGROUND
Radiosynovectomy (RSO) is widely used in rheumatoid arthritis (RA). Commercially available radiopharmaceuticals are costly, and therefore new agents may be of interest. Radiocolloids labelled with less costly and more accessible radionuclides are of interest to developing countries. We investigated the efficacy of different formulations in RA.


METHODS
In a multicentre effort, a cohort of 99 RA patients with knee involvement underwent RSO. Sixty-eight patients were treated with 184 ± 4 MBq Y-90 silicate (Y-90), 15 patients with 53 ± 11 MBq P-32 colloid (P-32), and 16 patients with 451 ± 110 MBq of Re-188 tin colloid (Re-188). Corticosteroid group (CSG) consisting of 46 patients received an intra-articular instillation of 20-40 mg triamcinolone. Pain response was evaluated by a 10-step visual analogue scale (VAS) before, 1 month, 3 months, 6 months and 12 months following the procedure.


RESULTS
In the RSO group (n = 99), pain relief by VAS from 6 ± 2 before to 5 ± 3, 4 ± 2, 3 ± 2 and 4 ± 2 at 1, 3, 6, 12 months after RSO was documented (Y-90 group: 6 ± 2 to 3 ± 2; P-32: 5 ± 2 to 3 ± 2, Re-188: 7 ± 2 to 4 ± 2 before vs. 6 months after therapy, respectively). The CSG VAS values were 6 ± 2 before and 5 ± 2, 4 ± 3, 5 ± 2 and 6 ± 2 at 1, 3, 6 and 12 months after corticosteroid instillation, respectively. Pain relief achieved with the three radiocolloid formulations did not differ significantly (P > 0.1). Pain relief at 12 months was more durable in RSO compared to CSG, P < 0.05. At 3 months, pain relief (>2 steps) was reported by 86% of RSO versus 67% of CSG, at 6 months 72 versus 46% and at 12 months 46 versus 21%. Side effects, i.e. swelling or transient pain increase, were recorded in 16% of patients but resolved within 1 month.


CONCLUSION
Therapeutic efficacy of RSO for RA of the knee applying either P-32, Re-188 or Y-90 provides comparable results. Pain relief by RSO is longer lasting as compared to corticosteroid instillation.