Background Disease relapse can occur in psoriatic arthritis (PsA) when tumour necrosis factor inhibitor (TNFi) therapy is withdrawn. Dose reduction of TNFi whilst maintaining disease control may be possible.
Objectives To determine feasibility of TNFi dose reduction in severe PsA patients in a real world setting.
Methods 83 PsA patients were identified from a Biologics Therapy Clinic database. Severe PsA was defined as patients with ≥3 tender joints and ≥3 swollen joints, and active arthritis despite adequate trials of ≥2 disease-modifying antirheumatic drugs (DMARDs). Using standardised questionnaires, rheumatologists recorded clinical characteristics, laboratory results, disease activity, medications and clinical outcomes. Criteria for dose reduction of TNFi therapy included DAS28-ESR ≤3.2 (low disease activity) for ≥6 months and patient agreement. TNFi dose was reduced by one-third [Adalimumab (ADA) 40mg 3 weekly; Etanercept (ETN) 50mg every 10 days; Infliximab (INF) 5mg/kg 3 monthly; Certolizumab (CER) 200mg 3 weekly; Golimumab (GOL) 50mg 6 weekly]. Patients were seen 12 weeks after starting TNFi therapy, then 24 weekly. Failure of dose reduction was defined as DAS28-ESR >3.2 or patient-defined disease recurrence. Patients who flared were reviewed and re-escalated to standard treatment dose.
Results All 83 patients had a clinical diagnosis of PsA by a consultant rheumatologist (96% satisfied CASPAR). 64% were males. 93% were Caucasian. Mean age was 52.3±12.1 years. Mean age of diagnosis was 40.6±12.1 years. Patients were diagnosed with PsA for mean of 11.3±6.6 years. 46% tried ≥3 DMARDs prior to biological therapy. 45% were current or ex-smokers. 63%, 24%, 11%, 2% were on their 1st, 2nd, 3rd and 4th biologic respectively. Mean DAS28-ESR prior to starting TNFi therapy was 4.2±1.0. Methotrexate (76%) was the most common DMARD used. Biologics used in order of frequency were: ADA (42%), ETN (25%), INF (15%), CER (8%) and GOL (7%). 18% (15/83) fulfilled criteria for TNFi dose reduction and had their TNFi reduced. 60% (9/15) successfully maintained TNFi dose reduction for a mean of 1.2±0.8 years. Disease activity prior to TNFi dose reduction was lower in patients successful in maintaining dose reduction compared to failures of TNFi dose reduction [mean DAS28-ESR 1.1±0.5 vs 2.1±0.9 respectively (p=0.021)]. Of those who failed dose reduction (6/15), re-instating standard dose of TNFi therapy re-captured low disease activity in all patients by 12 weeks, but with significantly higher disease activity compared to patients successfully maintained on TNFi dose reduction [mean DAS28-ESR 2.7±0.6 vs 1.3±0.5 respectively (p≤0.001)].
Conclusions Real world experience suggests that about 60% of individuals with severe PsA who achieve low disease activity, can be maintained on a reduced dose of TNFi therapy for 1 year. PsA patients with lower disease activity are better able to maintain dose reduction of TNFi therapy. Re-instating standard dose of TNFi therapy in those who flare can rapidly control disease activity again.
Disclosure of Interest None declared