Background/Purpose: Biological agents are used to treat chronic arthritis according to the standard dosages 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. Our objective was 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: Cross-sectional study which included all patients attended consecutively between June 2011 and November 2011 by a single clinician, and who had received ≥1 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. In rheumatoid arthritis (RA) patients we also analyzed disease activity (DAS28 score) and serum levels of C-reactive protein (CRP). The reduced dosage was defined as a lower dosage than recommended in the summary of product characteristics and was not based on a structured protocol.

Results: We included 170 patients (67% female); mean age: 51.1±14.3 years. Diagnoses were: 56.5% RA, 18.8% ankylosing spondylitis (AS), 11.8% psoriatic arthritis (PsA) and 12.9% miscellaneous (MISC), including 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 diagnoses. 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 ≥1 biological agent. At the time of analysis, 76 patients (44.7%) were receiving low dosages of biologicals (56% of etanercept patients, 55% adalimumab, 45% tocilizumab, 39% infliximab and 11% abatacept). Of the 76 patients, 51.3% had RA, 23.7% AS, 13.2% PsA and 11.8% MISC. Most commonly used low dosages were 50 mg every 15 days for etanercept, 40 mg every 3 weeks for adalimumab, 5mg 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%). Mean time of dosage reduction was 17.2±21.1 months. In RA patients, mean DAS28 score and CRP levels were lower in patients with reduced dosage than in patients with standard dosage (2.57 vs 3.47, p=0.09) and (0.37 vs 1.09, p=0.007), respectively, and the percentage of remission was higher (76.3% vs 30.7%, p=0.000). The medical decision at the time of data collection was to maintain low-dosage biological treatment in 63 patients (82.9%) due to low disease activity and/or remission, assessed by clinical judgment and regular scores.

Conclusion: 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 biological drugs.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-significant-number-of-patients-with-chronic-arthritis-received-a-reduced-dosage-of-biological-drugs-an-observational-study-in-clinical-practice/