Adherence to Methotrexate and Anti-TNF therapy in Rheumatoid Arthritis
Bernie McGowan1, Kath Bennett3, Carmel Silke1, Bryan Whelan1, 2
1North Western Rheumatology Unit, OLHM, Co. Leitrim 2Department of Medicine, NUIG, Galway 3Department of Pharmacology and Therapeutics, Trinity Centre for Health Sciences, Dublin 8
Nonadherence to prescribed medications is associated with disease flares and increased disability in patients with Rheumatoid Arthritis1, 2. Despite this, adherence rates to prescribed medicine regimes in people with RA are low, varying from 30 to 80%3.
To evaluate the effect of different concomitant DMARDs on the persistence with anti-TNF therapies in patients with RA.
This was a retrospective study involving a combined data from the HSE-PCRS and High Tech Drugs Scheme Databases. All new users of anti-TNF alpha > 16 years of age were identified from the HTD scheme from 2012-2014 inclusive. Non-persistence was identified at 6 months and 12 months postindex dispensing date. Time to non-persistence was examined using Cox Proportional Hazards models, with predictors of coprescribed DMARDs including methotrexate with or without sulfasalazine or leflunomide. Adjustments were also made for age, gender and number of co-prescribed drugs. Analysis was performed using SAS v9.3 (Cary Institute, USA) and significance at p<0.05 is assumed.
There were n=3094 new initiators of any anti-TNF page 35 alpha between Jan 2012 and June 2014 with sufficient data for analysis of non-persistence. 84.45% were persistent at 6 months and 68.6% were persistent at 12 months. Patients not coprescribed DMARDs were most likely to become non-persistent to therapy by 6 months. Patients receiving no DMARD or Sulfasalazine were more likely to discontinue their anti-TNF than patients receiving anti-TNF in combination with methotrexate at 12 months. Patients with increased number of co-morbidities demonstrated poorer persistence to treatments at 6 and 12 months.
Patients co-prescribed DMARDs in particular methotrexate show greater persistence to anti-TNFs than patients treated with anti-TNFs alone.