ASAS consensus process may guide ASDAS cutoff value for worsening in AxSpa

MADRID — A novel consensus process has been proposed for defining clinical worsening in axial spondyloarthritis, according to findings presented at the EULAR Annual Congress.

Anna Molto, MD, PhD, a rheumatologist at Cochin Hospital in Paris, and colleagues aimed to define a cutoff for the ankylosing spondylitis disease activity score (ASDAS) that can be used in future studies.

“The natural history of this disease is one of periods of remission followed by periods of flare or worsening,” she said. “We have to assess clinical worsening. There is no consensual definition of worsening.”

Molto noted that there is a consensus cutoff of a change of 1.1 in the ASDAS for improvement of disease.

Between 2014 and 2017, the researchers conducted a literature review, case vignettes and an Assessment of Spondyloarthritis International Society (ASAS) discussion. These have been presented or published in other formats and meetings. The results of these steps led the group to arrive at three changes in the ASDAS that were considered as cutoffs for worsening disease. Those were cutoffs of at least 0.6 points, 0.9 points, and 1.1 points.

In the current study, the group tested those cutoff values. They tested the sensitivity and specificity of each cutoff value by comparing 1,196 patients from a real-life prospective study to patient-reported worsening in a cohort of 127 patients. At a cutoff of at least 0.6, the sensitivity was 55% and the specificity was 91%. For a cutoff of at least 0.9, the sensitivity was 38% and the specificity was 96%. At a cutoff of at least 1.1, the sensitivity was 33% and the specificity was 98%.

“A consensus was reached among the ASAS members to define worsening as a deterioration of at least 0.9 points,” Molto said. “Sensitivity decreases with a greater change for both patient and physician. Patients consider themselves worse with lower thresholds.”

For the data collection, at the second visit, clinicians asked patients if they felt better, if there was no change or if they were worse.

“If they were feeling worse, we asked if the symptom state was acceptable or not,” she said. “We also asked if they needed treatment intensification.”

Findings indicated 191 patients in the cohort reported being worse at the second visit compared with the baseline visit, while 127 patients reported being worse and requiring an intensification of treatment.

The ASAS group failed to reach a consensus on a BASDAI-based definition of worsening.

Molto concluded that the prolonged process of arriving at a change of 0.9 in ASDAS score as the cutoff for worsening was “data-driven,” and that it should be applied in future clinical trials. — by Rob Volansky

Reference:

Molto A, et al. Abstract #OP0188. Presented at: EULAR Annual Congress; June 14-17, 2017; Madrid.

Disclosure: Molto reports that the study was supported by ASAS.