Background/Purpose: The concept of difficult-to-manage axial spondyloarthritis (D2M-axSpA)[1], may vary over time. Transitions between D2M and non-D2M classifications throughout the disease course remain unclear. This study evaluates the consistency of the D2M-axSpA classification over time and identifies differences of non-D2M and persistent and episodic D2M-axSpA cases at the b/tsDMARD initiation.

Methods: This is a cross-sectional assessment patients with axSpA who were on b/tsDMARD for at least one year and visited our rheumatology clinic between April-December 2023. Patients were assessed at two timepoints for fullfillment of D2M-axSpA: first visit at the study inclusion period and second visit between 6-12 months after the first visit. Using these two-timepoint data patients were categorized into three groups as follows:’persistent D2M’ (D2M-axSpA’ patients at both assessments), ‘persistent non-D2M'(non-D2M-axSpA’ patients at both assessments), ‘episodic D2M-axSpA’ (D2M-axSpA in only one of the assessments). Demographic, clinical and disease activity indices as well as comorbidities of the patients at the initiation of b/ts DMARD were evaluated and compared between groups. The factors associated with D2M-axSpA status on univariate analysis with significance at the 0.20 level were entered into a multivariable model. Backward elimination method was used at a significance of 0.05 level.

Results: Overall 888 patients were included in this assessment . From the initial D2M-axSpA patients(n=119), 52.1% were persistent-axSpA, 33.6% were episodic D2M-axSpA. 14.2% (17/119) did not attend follow-up visits. Of the initial non-D2M-axSpA (n=769), 82.5% were persistent non-D2M-axSpA, 5.33%were episodic D2M-axSpA, and 12.09% did not participate in follow-up visits (Figure 1). Persistent D2M-axSpA patients were more often female and had higher rates of hypertension, COPD/asthma, and diabetes mellitus. BASDAI and VAS global scores were significantly higher in the persistent D2M-group at b/tsDMARD initiation (Table 1). In the multivariable logistic regression analysis, a higher BASDAI score at the initiation of b/tsDMARD therapy was identified as a significant factor associated with the development of D2M-axSpA (either episodic or persistent) among patients initially classified as non-D2M (OR: 1.48 [1.15–1.91], p = 0.002) (Table 2).

Conclusion: Our study revealed that 33.6% of patients initially diagnosed with D2M-axSpA eventually transitioned to a non-D2M state and overall 10% of the population has transitioned from one category to another. Persistent D2M-axSpA patients were more often female and had a higher prevalence of comorbidities. Physicians should be aware that D2M-axSpA criteria fullfilments may change over time, with factors that potentially affecting subjective measures like BASDAI, HAQ, and VAS global scores.References:1. Poddubnyy D, B.X., et al ., Arthritis Rheumatol, 2024. 76.

Figure 1. Temporal changes in D2M AxSpA and Non-D2M AxSpA patients

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/classification-of-difficult-to-manage-axial-spondyloarthritis-a-real-world-cohort-study-evaluating-the-asas-2024-criteria-over-time/