Background The monoclonal anti-TNF antibodies infliximab and adalimumab and etanercept are equally effective in rheumatoid arthritis, ankylosing spondylitis, psoriasis, psoriatic arthritis and inflammatory bowel disease. Poor persistence with, and adherence to, biologicals can undermine the effectiveness of these drugs. There are no standardised methods for tracking persistence with, and adherence to, biologicals.

Purpose The aim of this study was to evaluate the patient adherence to treatment through the compliance ratio. The cost of treatment per day was also calculated for each drug.

Materials and methods The study was carried out in 2010. The following data were loaded in the database in use at the pharmacy, FarmaDDSS: patient demographics, drug used, dosage and date of delivery of the drug. So, it was possible calculate the drug use parameters Received Daily Dose (RDD) and Prescribed Daily Dose (PDD) for comparison with the Defined Daily Dose (DDD). Patient adherence to treatment was calculated as the ratio of RDD to PDD.

Results Of the 207 patients treated in 2010, 52 had etanercept, 102 adalimumab and 53 infliximab. The RDDs were 6.4, 3.9 and 7.2, respectively. The PDDs were 7,11, 3,00 and 3,78. Appropriateness (RDD/DDD) and adherence (RDD/PDD) were 0.9 for etanercept, 1.3 for adalimumab and 1.9 for infliximab. The cost per RDD was € 33.47, € 50.00 and 39.94, respectively.

Conclusions Etanercept and adalimumab showed a good clinical profile. Infliximab appears to betaken at twice the dose. It's very important to follow the patients by developing an outcomes research system. The use of a dedicated database such as FarmaDDSS can facilitate the measurement of rates of persistence with, and adherence to, biologicals.