Background The evaluation of the direct costs of chronic diseases has become an essential tool so as to make an adequate provision of health resources, which, also, implies an attempt to optimize treatments. Due to the high cost of biological drugs, this evaluation has a considerable importance in the treatment of rheumatic diseases.
Objectives To evaluate the dose patterns of Etanercept (ETN), Adalimumab (ADA) and Infliximab (IFX) in patients with inflammatory rheumatic diseases such as Rheumatoid Arthritis (RA), Ankylosing Spondylitis (AS) and Psoriatic Arthritis (PsA) in a tertiary hospital. To calculate, for each study drug, the average annual cost per patient and the percentage value of doses received according to the theoretical ones.
Methods Retrospective study in patients treated with ADA, ETN and/or IFX for at least six months between January 2009 and April 2013 and diagnosed with RA, AS or PsA by the Rheumatology Department. Periods of treatment, doses dispensed in hospital pharmacy office and periods of temporary interruption, were obtained. The cost of each drug (official data) was: ADA 40 mg, €494.6 ETN 50 mg, €227.8; ETN 25 mg, €113.9; and IFX 100 mg, €516. Administration costs of the infusion of IFX (€173.7) were added.
Results 507 patients, 200 men and 307 women, with a mean age of 56.93±15.67 years were included. 73.2% (371) of the patients had RA, 14.8% (75) PsA and 12% (61) AS. Thus, 42.6% (216) of the patients received ADA, 31.4% (159) ETN and 26% (132) IFX. The average annual cost per patient for all patients studied was 11957.96±3416.77€ [95% CI:11659,83-12256,08] and the treatment with ETN was significantly cheaper, 10172.64±2063 06€ [95% CI: 9849,49-10495,79], than Adalimumab, 13073.19±2733.21€ [95% CI: 12706,63-13439,75] (p<0.001) and Infliximab, 12283,53±4655.40€ [95% CI:11481,93-13085,10] (p<0.001). Statistically significant differences were also observed in the average percentage value of doses received according to the theoretical ones (summary product information): 85.0% for ETN, 101.66% for ADA and 112.48% for IFX (p<0.001). No statistically significant differences were observed in the average length of treatment: 37.61 months, 38.32 months and 36.07 months for ADA, ETN and IFX, respectively (p=0.444).
Conclusions Etanercept has proved to be the most cost-effective treatment in these rheumatic diseases compared with the most common biological treatments. Because there is a lack of studies evaluating the safety and efficacy between these drugs, should be considered the possibility of a drug selection algorithm based on the associated cost, paying always attention to the presence of possible contraindications. This would result in an improvement of the efficiency of these treatments and, in addition, in a containment of the healthcare expenditure.
Disclosure of Interest D. Gόmez Gόmez Grant/research support: by Pfizer, A. Colόn Lόpez de Dicastillo: None declared, M. Ochagavía Sufrategui: None declared, F. Arnaiz de las Revillas Almajano: None declared, M. Valero Domínguez: None declared