Drug Survival in Patients with Inflammatory Arthritis Treated with Reduced Dose Anti-TNF-?: Results of a 4 Year Observational, Prospective Study
John Stack, Claire Louise Murphy, Linzi Martin, Clara Bannon, Trevor Duffy, Eithne Murphy, Maurice Barry
Rheumatology Department, Connolly Hospital Blanchardstown
Anti-TNF-? drugs are effective treatments for patients with inflammatory arthritis (IA). They are however expensive and their use carries a significant cost burden to the tax payer and society. Anti-TNF-? dose reduction in patients with IA who are in remission may lead to significant cost savings.
The aim of this prospective, non-blinded, non-randomised, observational study was to observe whether patients with IA (rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA)) could successfully dose reduce anti-TNF-? over a 4 year period and to estimate the cost savings associated with dose reduction.
Anti-TNF-? dose reduction was offered to patients with IA who were in remission as defined by standardized disease activity indices (DAS-28 <2.6, BASDAI < 4). Patients on etanercept were reduced from 50mg weekly to 50mg fortnightly. Patients on adalimumab were reduced from 40mg fortnightly to 40mg monthly. Patients who agreed to dose reduction were invited to participate in the study which commenced in 2010. page 26 Patients were assessed for disease activity at 3, 6 , 12, 24, 36 and 48 months. Patients who remained in remission were encouraged to stay on the reduced dose anti-TNF-?. The primary end-point was the number of patients remaining on reduced dose anti-TNF-? at 2 years. The study was then extended out to 4 years. Cost savings were estimated by deducting the actual total cost of anti-TNF-? used from the theoretical cost of using full dose anti-TNF-? had dose reduction not occurred.
79 patients with IA in remission were recruited. 57% had RA (n=45), 13% PsA (n= 10) and 30% AS (n= 24). 57% (n=45) were on etanercept and 43% (n=34) were on adalimumab. The percentage of patients who remained on reduced dose anti-TNF-? at 4 years was 36% (n=29). Of the patients who successfully dose reduced at year 1 (n=42), a majority (69%, n=29) were able to maintain the dose reduction up to year 4. A greater percentage of AS patients (52 % n=12) were able to maintain dose reduction up to year 4 but this was not significant. Net savings to the exchequer of €1,211,697 were estimated. The average cost saving per patient included in the study per year was €3834.
Dose reduction of anti-TNF-? therapy in patients with IA in remission is feasible and can yield significant cost savings. Further studies could be designed to help define which patients are more likely to successfully dose reduce.