AxSpA Treatment Intensification in Practice Linked With Higher ASDAS Cutoff Than Recommended

In clinical practice, intensifying treatment for axial spondyloarthritis (axSpA) is associated with a higher Ankylosing Spondylitis Disease Activity Score (ASDAS) cutoff value than recommended, according to a poster presented at the European Alliance of Associations for Rheumatology (EULAR) 2024 Annual European Congress of Rheumatology.¹

It is recommended that treatment intensification in patients with axSpA be based on disease activity changes defined by the ASDAS, the authors explained. In those with what is considered high disease activity, or an ASDAS score of at least 2.1, treatment adaptation is recommended.

AxSpA is a type of inflammatory arthritis characterized by back pain and stiffness that can be severe and debilitating, and it can lead to non–joint-related symptoms such as eye inflammation, diarrhea, fatigue, and more.² The ASDAS score is a composite index that assesses disease activity in ankylosing spondylitis, which is also known as axSpA.³

Although the cutoff value of 2.1 is the current recommendation, authors of the poster presented at EULAR 2024 explained that this recommendation is not always followed in clinical settings.¹

While the ASDAS cutoff value of 2.1 is the current recommendation, authors of the poster presented at EULAR 2024 explained that this recommendation is not always followed in clinical settings - fizkes - stock.adobe.com

“The ASDAS was developed for research, and it is unknown how well it performs in daily practice. Possibly, the cut-off of 2.1 as currently endorsed may be too strict in this setting,” the authors wrote. Therefore, their study aimed to assess which cutoff values corresponded the best with treatment intensification when treating patients with axSpA in the clinical practice setting.

A total of 350 patients with axSpA and an ASDAS measurement of at least 1 between 2016 and 2022 were included in the study, which used data from a prospective multicenter Dutch registry for patients with spondyloarthritis. Switching to a higher dose or frequency of the same drug, switching to another drug, or adding a new drug to the current treatment regimen were all considered treatment intensification. The number and types of treatment intensification were analyzed along with ASDAS at the time of intensification.

Receiver operating characteristic (ROC) curve analyses estimated how well the ASDAS could differentiate between intensification or non–treatment intensification, as well as to determine the ASDAS cutoff that is most accurate in the real-world study population.

Among the patients included in the study, 2265 ASDAS measurements were available at a median (IQR) follow-up of 2.8 (1.0-4.4) years. The mean (SD) ASDAS was 2.3 (1.0), and 231 patients (66%) were on biological or synthetic disease-modifying antirheumatic drugs (DMARDs) at some point during the follow-up period. Treatment intensification occurred following 236 ASDAS measurements overall (10.4%), and 163 patients (69.1%) were already on anti-inflammatory treatment at the time of intensification.

Intensification of treatment commonly involved switching to another drug, often in the same class, or adding a drug to the existing regimen. Conventional synthetic DMARD and corticosteroid use were both limited.

The mean ASDAS was higher at times when treatment was intensified vs at non–treatment intensification time points, as was the proportion of patients with an ASDAS of 2.1 or higher. The mean (SD) ASDAS was 3.0 (1.0) at intensification time points vs 2.3 (1.0) at nonintensification time points. At treatment intensification time points, 84.3% of patients had an ASDAS of 2.1 or higher, compared with 54.0% of patients at nonintensification time points.

In an analysis of all ASDAS measurements, the authors found that the ROC area under the curve (AUC) was 0.71 (95% CI, 0.68-0.75) with an optimal cutoff value of 2.7. The sensitivity of this cutoff was 69%, the specificity was 66%, and the Youden index was 0.35. When only 1 measurement per patient and calendar year was used—a total of 1153 measurements—the findings were similar, with an AUC of 0.74 at an ASDAS cutoff of 2.7.

The authors noted that the optimal ASDAS varied significantly from year to year, with a range of 2.3 to 2.8, but that it was consistently higher than the recommended 2.1 cutoff.

“In daily practice, TI is associated with a higher ASDAS cut-off value than the recommended one (≥2.1). Possibly, rheumatologists believe the recommended cut-off to be too stringent or consider other factors than disease activity when making treatment decisions,” the authors concluded.

References

1. Webers C, El-Din RN, Been M, Vonkeman HE, Tubergen AV. Which ASDAS cut-off corresponds best to treatment intensification in patients with axial spondyloarthritis in daily practice? Poster presented at: EULAR 2024 Congress; June 12-15, 2024; Vienna, Austria. Poster OP0060.

2. Axial spondyloarthritis. Cleveland Clinic. Updated March 20, 2023. Accessed June 21, 2024. https://my.clevelandclinic.org/health/diseases/24843-axial-spondyloarthritis

3. Machado P, Landewé R, Lie E, et al. Ankylosing Spondylitis Disease Activity Score (ASDAS): defining cut-off values for disease activity states and improvement scores. Ann Rheum Dis. 2011;70(1):47-53. doi:10.1136/ard.2010.138594