Background Biological agents are used to treat chronic arthritis according to the standard doses from phase III clinical trials. However, in some patients, a good response to treatment may allow the dosage to be reduced, the timing lengthened, and costs reduced.
Objectives To analyze a strategy of dosage reduction of biological agents in patients with chronic arthritis attended by the rheumatology department of a tertiary hospital.
Methods We performed a cross-sectional study that included all patients, attended consecutively between June 2011 and November 2011 by a single investigator, that had received at least one dose of a biological agent in 2011. Data analyzed were: demographic characteristics; diagnosis and disease duration; DMARD therapy; dosage, type and duration of biological agent used; time on reduced dosage and reason for dosage reduction. The reduced dosage was defined as a lower dosage than recommended in the product technical details and was not based on a structured protocol.
Results We included 170 patients (67.1% women) with a mean age of 51.1±14.3 years. Diagnoses were: 56.5% rheumatoid arthritis (RA), 18.8% ankylosing spondylitis (AS), 11.8% psoriatic arthritis (PsA) and 12.9% miscellaneous (MISC), which included 9 juvenile idiopathic arthritis, 3 undifferentiated spondyloarthropathy, 3 uveitis, 2 connective tissue disorder and 1 SAPHO. Mean disease duration was 14.5±8 years, with no differences between conditions. Mean duration of current biological therapy was 47.7±35.6 months, with 134 patients receiving TNF blockers and 36 patients receiving non anti-TNF (abatacept, rituximab and tocilizumab). 53% of patients received concomitant therapy with DMARDs, mainly in the RA group, and 28.2% had received one or more biological agent. At the time of analysis, 76 patients (44.7%) received low dosages of biologicals (51.3% of etanercept patients, 23.7% adalimumab, 14.5% tocilizumab and 10.5% infliximab). The distribution of diseases was: 51.3% RA, 23.7% AS, 13.2% PsA and 11.8% MISC. The most-commonly used low dosage was 50 mg every 15 days for etanercept, 40 mg every 3 weeks for adalimumab, 5 mg/kg every 9-10 weeks for infliximab and 6 mg every 4 weeks for tocilizumab. The reason for dosage reduction was disease remission in 68 patients (89.5%) and low activity in 8 (10.5%). The mean time of dosage reduction was 17.2±21.1 months. The medical decision at the time of the data collection was to keep the low dosage of biological treatment in 63 patients (82.9%) due to low disease activity and/or remission, assessed on clinical judgment and regular scores.
Conclusions Near half our chronic arthritis patients receiving biological therapy were able to reduce the dosage to below that of established clinical guidelines, preserving remission or low disease activity in many cases. This dosage reduction was observed both in RA and spondyloarthropathies, and with different mechanisms of drug action.
Disclosure of Interest None Declared