Background A cost evaluation was performed due to the high cost of biological treatment (BT); possible benefits of optimising BT were also investigated.

Purpose To analyse the economic impact of optimising biological treatments for rheumatoid arthritis (RA) and other spondyloarthritis (SpA) conditions such as ankylosing spondylitis and psoriatic arthritis.

Materials and methods Retrospective observational study of all patients treated in the BT Rheumatology Service from March to September 2013. For optimisation (dose reduction and/or expansion of dose interval), patients were selected according to clinical remission (DAS28 <2.6), low clinical activity (DAS28 <3.2; BASDAI <4) and clinical recommendations. The following data were collected: diagnosis, biological treatment, demographic characteristics, date and dose/interval after and before adjustment. The net unit price of the drug was used to perform the cost calculation.

Results 365 patients were treated with BT, 203 patients (55.6%) with RA and 162 (44.4%) with SpA. 81 patients (22%) were candidates for optimising treatment, 40 patients (49.4%) with RA and 41 (50.6%) with Spa. Mean age: 54.78 (SD:13.69) years old; 56% female and 45% male. 37 patients were in clinical remission, 30 patients in low clinical activity and 14 were chosen due to clinical recommendation.

The optimisation regimens were defined as follows:

• Golimumab (1.23%): 1 patient expansion of dose interval from 4 to 6 weeks;

• Adalimumab (12.34%): 9 patients expansion of dose interval from 2 to 3 weeks and 1 patient to 4 weeks;

• Etanercept (29.62%): 16 patients expansion of dose interval from 7 to 10 days; 5 patients to 15 days, 2 patients to 21 days and 1 patient to 30 days;

• Tocilizumab (2.46%): 1 patient dose reduction to 6 mg/kg and 1 patient expansion of dose interval from 4 to 6 weeks;

• Rituximab (9.87%): 7 patients expansion of dose interval from 6 to 7 months and 1 patient to 9 months;

• Abatacept (3.7%): 2 patients dose reduction from 750 mg to 500 mg and 1 patient expansion of dose interval from 4 to 5 weeks;

• Infliximab (40.74%): 2 patients expansion of dose interval from 6 to 7 weeks, 27 patients to 9 weeks, 2 patients to 10 weeks, 1 patient dose reduction from 5 mg/kg every 9 weeks to 4 mg/kg every 12 weeks.

At the moment all patients are in clinical remission, except a patient with IFX who had to return to the previous dose because of skin diseases.

Patient- year cost (theoretical doses) would be 835.538 €, while patient-year cost (optimised doses) was 594.102 €, which means a saving of 241.435 € (29%). The most saving was achieved with the optimisation of adalimumab and etanercept treatment, making savings of 36% and 39%, respectively.

Conclusions The optimisation of BT could reduce the cost while maintaining efficacy and safety of treatment.

The optimisation of BT begins with a rational selection of the patient, according to criteria of clinical activity and clinical recommendations rather than looking at the costs.

No conflict of interest.