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Some experiences with intra-articular (IA) infliximab treatment in patients with refractory monoarthritis have been reported, even though these studies have important limitations including small sample size and short trial duration.1–4
Aim of this study was to evaluate the efficacy and safety of IA infliximab administration in a larger cohort of patients. We studied 10 patients with rheumatoid arthritis (RA) and seven with psoriatic arthritis (PsA) with active monoarthritis lasting at least 3 months, refractory to disease-modifying antirheumatic drugs (DMARDs) and to IA glucocorticoids.5 6 DMARDs dose had to be stable for at least 6 weeks before IA injection of infliximab, and it was maintained stable throughout the follow-up. IA methylprednisolone had to have been injected at least 6 weeks before the procedure. Concomitant treatment with anti-TNFα other than infliximab was permitted; indeed the biologic agent was stopped 2 weeks before and restarted 2 weeks after IA procedure. After removing synovial fluid, IA infliximab was injected at dosage of 100 mg for the knee, 50 mg for the ankle, 25 mg for the wrist.
Patients were evaluated at baseline, and after 2 and 12 weeks for visual analogue scale (VAS) for pain, and the degree of swelling and tenderness (0–3).2 3 The sum of swelling and tenderness scores provided the total arthritis score (0–6). Erythrocyte sedimentation rate (ESR, mm/h) and C-reactive protein (CRP, mg/dl) were also evaluated. Ultrasonographic examination of the inflamed joint was performed by the same rheumatologist, an arbitrary scoring system (0–6) for assessment of inflamed joint was applied considering synovial hypertrophy (0–3) and power Doppler evaluation (0–3).7–9
Two and 12 weeks after treatment a clinical response was seen in nine of 10 (90%) RA patients. Regarding patients with PsA, after 2 weeks a clinical response was seen in six of seven (85.7%) patients, and after 12 weeks in four of seven (57.1%) patients. No local or systemic adverse reactions were documented. In patients with RA and PsA the US score correlated positively with the total arthritis score at 12 weeks (p<0.05).
The results of this study suggest that patients with RA and PsA with refractory monoarthritis could be successfully treated with IA infliximab. The ultrasonographic features of synovitis significantly improved during the follow-up and correlated positively with the outcome measures, confirming the biologic effect of IA infliximab. In patients with a secondary failure of treatment, a second IA injection of infliximab determined a complete response in all the cases.
IA infliximab resulted efficacious in five of six patients who were receiving systemic TNFα antagonists other than infliximab. Changing anti-TNFα and inoculating it directly in the site of inflammation determined a good clinical response. Use of IA infliximab in this cohort of patients with RA and PsA with resistant monoarthritis provides evidence that it could be an efficacious and safe therapeutic option determining a sustained clinical improvement also in patients on other anti-TNFα. Considering the sample size of this study, larger prospective trials are needed in order to confirm these preliminary findings.
Competing interests: None.
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