Identifying the Target
Maxime Dougados, MD, professor of rheumatology at Cochin Hospital and a lead investigator in the study, pointed out that treat-to-target studies are fraught with questions that must be handled delicately. The target of the treatment isn’t necessarily straightforward, he said, pointing out the many extra-spinal features of AxSpA, including peripheral arthritis, uveitis and psoriasis. Certain patients may be at greater risk for certain complications, depending on their history and comorbidities, he said.
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Explore This IssueSeptember 2020
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Once clinicians identify the domain to be targeted, they must take care to measure it properly. Many indices can be used to measure disease activity, for example, as well as cardiovascular risk factors.
Collecting and reporting outcome measures are critical, and many rheumatologists don’t routinely collect many of the relevant data points. A fellow studying at his center reviewed the electronic medical records of 30 rheumatologists in the Paris area, finding that less than 30% of patients had a recorded BASDAI, and less than 1% had a recorded ASDAS, Dr. Dougados said.2
As for the TICOSPA data, other trials will likely be needed before physicians get comfortable with a treat-to-target strategy. “In medicine, usually we are more comfortable when you have confirmation by two or three different strategy trials,” Dr. Dougados said. “Unfortunately, so far, I am not aware of other ongoing clinical trials in this area.”
Still, he said, a treat-to-target approach “is not only feasible, but has to be considered in axial spondyloarthritis for each patient. This approach has to be individualized, because of the possibility of different clinical presentations.”
Measuring Disease Activity
Désirée van der Heijde, MD, PhD, professor of rheumatology at Leiden University Medical Center, The Netherlands, who developed the ASDAS, said the measure was an appropriate target for the trial, saying that disease activity should be the target in such a strategy comparison and that ASDAS performs better than the BASDAI in many important areas. Developed in 1994, the BASDAI is the older measure, but considered easier to use; the ASDAS was unveiled in 2007. (Note: Dr. van der Heijde does not have a copyright to, and receives no royalties from the use of, the ASDAS, which is widely available.)
A major difference is that the ASDAS includes an acute phase reactant but the BASDAI includes only patient-reported outcomes. The ASDAS weights the five domains it considers differently, but the BASDAI gives the same weight to each of the five domains it considers. That’s important, Dr. van der Heijde said, because certain domains can have so much overlap with other domains that one may not add any extra useful information.
Each level of increase in the ASDAS correlates with an increase in structural progression, but this is not so with the BASDAI, she said. Also, the ASDAS relates better to both the patient and physician global assessments, while the correlation between the BASDAI and physician global assessment is poor. The ASDAS is better at discriminating between a patient’s assessment of high disease activity and the physician’s assessment of high disease activity.3,4
Despite the BASDAI’s ease of use, the ASDAS is the better choice when comparing treatment strategies in these patients, said Dr. van der Heijde.
“It’s ASDAS which is performing better,” she said, “if you take all these things together.”