Patients with axial spondyloarthritis have a chronic, immune-mediated inflammatory disease that tends to localize to the sacroiliac joints and spine. Ankylosing spondylitis is, perhaps, the most representative of this group of diseases. Rheumatologists treat patients with axial spondyloarthritis with biologics, such as tumor necrosis factor inhibitors (TNFi’s), which can improve quality of life, activity and functionality. Unfortunately, TNFi treatment is expensive and is associated with the possibility of long-term side effects. Investigators thus seek a personalized medicine approach in which clinical and biological markers are used to identify those patients most likely to benefit from TNFi’s, while at the same time minimizing drug exposure to those who are not expected to benefit.
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Can Treatment Dose Be Reduced?
Given the costs and potential long-term side effects of TNFi therapy, rheumatologists have wondered whether patients in remission require the full treatment dose. The answer from clinical practice and patient registries appears to be that patients with longstanding ankylosing spondylitis who achieve sustained clinical remission can reduce their treatment dose.
Unfortunately, rheumatologists lack both a uniform definition of reduced dose and a uniform definition of remission. Absent a uniform definition, a reduced dose is any dose below that indicated on the package insert. Likewise, absent a uniform definition of remission for patients with axial spondyloarthritis, physicians tend to rely upon the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the C-reactive protein.
In January, investigators from Spain published the results of the first randomized trial in support of the non-inferiority of reduced-dose TNFi therapy compared with full-dose TNFi’s in patients with spondyloarthritis.1 They randomized patients who were in clinical remission into what they described as a conservative TNFi reduction schedule that brought the TNFi dose down to approximately 50% of the recommended dose, or into a standard dose cohort. The group defined clinical remission as BASDAI ≤2, no clinically active arthritis or enthesitis, and C-reactive protein within normal limits for ≥6 months.
The researchers in Spain found that patients in remission maintained low disease activity for a year equally well, whether they were randomized to reduced-dose TNFi’s or standard-dose TNFi’s. Moreover, the results suggested that serious adverse events, less serious events and infections occurred at only one-third the rate in the reduced-dose group compared with the full-dose group. This difference did not, however, reach statistical significance, probably due to the small sample size (i.e., 126 patients). Moreover, because the investigators were only able to obtain serum samples from half of the study population, their study was not powered to identify the patients who had a higher chance of maintaining a low disease activity after reduction of their TNFi dose.