Abstract
INTRODUCTION: Methotrexate (MTX) is the bed rock of inflammatory arthritis management. However, intolerance is a limiting factor for drug optimisation and retention. There is data to suggest subcutaneous (SC) MTX is better tolerated. It is less clear whether this strategy is effective in those where the oral preparation is inefficacious and its potential to avoid escalation to biologic therapy. OBJECTIVES: To analyse the reasons for switching to SC MTX in a real-world setting, clinical outcomes achieved and proportion requiring biologic prescription. MATERIALS AND METHODS: A retrospective survey of patients prescribed SC MTX in a university teaching hospital identified 352 patients. 298 switched from oral to SC MTX- 164 stopped oral MTX due to side effects, 134 stopped due to inefficacy, and 54 started SC MTX as first line therapy. 103 patients progressed to biologic therapy. Rheumatoid arthritis (RA): DAS-28 improved from a mean of 4.06 (0.63-8.06) to 2.83 (0.14-7.32) following the switch (p<0.0001). Psoriatic arthritis (PsA): total joint count improved from a mean of 7 (0-42) to 2 (0-25) (p<0.0001). Swollen joint count improved from a mean of 2 (0-26) to 1 (0-6) (p=0.09). DISCUSSION: SC MTX is an effective solution for RA and PsA, irrespective of whether oral MTX is inefficacious or intolerable. Where oral MTX was ineffective, a switch to SC achieved low disease activity despite multi-morbidity, long disease course and protracted oral MTX exposure. This intervention prevented over two-thirds of patients requiring biologics. SC MTX is a durable strategy with excellent disease outcomes and substantial economic benefits.