Background Etanercept 50mg/week (ETN 50) has demonstrated significant efficacy in patients with rheumatoid arthritis (RA), psoriatic arthropathy (PA) andAnkylosing spondylitis (AS). In patients in clinical remission with standard dose, a dose reduction to etanercept 25 mg/week (ETN 25) could be done. This strategy of dose reduction could have advantages in terms of safety and costs.

Objectives Determine the clinical and economic impact of the use of ETN 25 in RA, PA and AS patients in clinical remission.

Methods Observational, retrospective cohort investigation of patients in an off-label programme taking ETN 25 for at least 6 months between January 2006 and January 2013. Inclusion Criteria: patients treated with ETN 50 that achieve and maintain clinical remission (DAS28<2.6 or BASDAI<2) during 1 year and slow worsening of structural changes were selected to change their standard dose of ETN 50 to ETN 25. We collected age, sex, indication, duration (in years) of ETN 25 during the study period. In these patients, we simulated the cost of treatment with etanercept as if they had received ETN 50 during their ETN 25 respective periods. Prices of Enbrel^® 25 mg and 50 mg were taken from officially published price bulletins from the Spanish Medication Agency (PVL+IVA).

Results 39 patients (18 women; age 53±7 years; 24 RA, 7 PA, 8 AS) received etanercept at 25 mg once-weekly for at least 0.5 years during the period study (mean 2.5±2.2 years; range 0.5-7.0 years). At 31^st Jan 2013, 29 patients continued on ETN 25 (17 RA, 4 PA and 8 AS) with a mean ETN 25 therapy of 2.5±2.6 years. 10 patients discontinued ETN 25 during the period of study (mean 2.3±1.5 years). 17 (70%) RA patients continued on ETN 25, 7 discontinued due to: 5 patients due to reactivation of RA (4 switched to ETN 50 and 1 switched to adalimumab, all patients achieved clinical remission) and 2 patients due to adverse reactions (one allergic reaction, one uveítis). 4 (57%) PA patients continued on ETN 25, 3 discontinued due to: 2 patients due to reactivation of PA (switched to ETN 50 and achieved clinical remission) and 1 patient due to adverse reactions (myocardial infarction). All AS patients continued on ETN 25. Total associated costs of this low dose strategy throughout the observation period were 561.332€. If these patients had been treated with the labelled etanercept dose, the total cost of therapy would have been 1.122.664€. The implementation of the once-weekly ETN 25 in these patients saved 561.332€ during 7 years. This cost savings achieved with a once-weekly regimen could lead to treat approximately 47 additional patients with RA, PA or AS without increasing the total cost of etanercept therapy during the period study.

Conclusions ETN 25 produces important cost savings when used in patients with slow worsening of structural changes who maintain clinical remission for at least 1 year with ETN 50. The use of this dose in these patients is associated with an important decrease of overall costs and allows us to treat more patients with the same budget.

Disclosure of Interest None Declared