Background/Purpose:

Remission is the current target of management of chronic rheumatic diseases. Whereas in rheumatoid arthritis remission criteria have been recently proposed, in spondyloarthritis, no activity score allows a clear definition for remission. SpA activity is evaluated with the BASDAI score (Bath Ankylosing Spondylitis Disease Activity Index) and more recently with the ASDAS (Ankylosing Spondylitis Disease Activity Score). Thresholds for the ASAS score have been proposed to classify disease activity (inactive, moderate, active, very active), but no remission threshold was defined.

The aim of this study was to evaluate a threshold for remission in SpA patients.

Methods:

In this prospective study, a questionnaire answering the question: “do you consider the disease in remission at the present time ?” was filled by the patient with Spa (according to ASAS classification criteria)  and the rheumatologist. Data allowing BASDAI, ASDAS-CRP and ASDAS-ESR calculation were collected, and PASS (Patient Acceptable Symptomatic State) was also assessed with a specific question at the same time. Thresholds were defined by building ROC curves for remission according to the patient’s and to the rheumatologist’s opinion.

Results:

One hundred and fifty patients were prospectively included, 67.3 % men, mean age 43.2 ± 11.5 years. HLA-B27 was positive in 84.5 % of the patients; SpA was axial in 81.7 %. Mean CRP was 8.6 ± 13.5 mg/l, and mean ESR 17.4 ± 16 mm/hour. PASS was considered by 56.6% of the patients. For disease activity, 47.3 % of the patients had a BASDAI score less than 4 / 10, and 19.2 % an ASDAS-CRP score less than 1.3 (inactive disease) (19.4 % for the ASDAS-ESR score). The thresholds of activity scores for remission defines by ROC curves are reported in table :

Threshold of activity score (ROC curves)	Remission « patient » N : 41 / 128	Remission « physician » N : 49 / 143	PASS in case of remission « patient » N : 41 / 128
ASDAS-CRP 95 % CI Sensibility % Spécificity %	≤ 1.6 0.67 – 0.84 62.2 86.3	≤ 1.8 0.82 – 0.94 75.6 91	≤ 2.2 0.82 – 099 93.3 100
ASDAS-ESR 95 % CI Sensibility % Spécificity %	≤ 1.7 0.71 – 0,.87 63.9 87	≤ 2 0.76 – 0. 90 75.6 82.2	≤ 2.4 0.76 – 0.9 71.4 81.6
BASDAI 95 % CI Sensibility % Spécificity %	≤ 3.6 0.71 – 0.86 75.6 75.9	≤ 3.6 0.81 – 0.93 83.7 79.4	≤ 4.1 0.80 – 0.90 75.7 85

Conclusion:

This is the first study tempting to define in a large series of patients in real life a threshold for remission in SpA with an ASDAS –CRP less than 1.6. These results corresponding to the patients reported definition are somewhat different from those endorsed by the ASAS classifying SpA as inactive for a threshold less than 1.3. These differences may be related to different study methods: randomized controlled studies, thresholds evaluated by experts at one hand, and real life situation, thresholds evaluated by the patients at the other hand. However, our results are coherent since the remission threshold is lower than PASS, but raise the question of the definition of remission in SpA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/remission-in-spondyloarthritis-asdas-and-basdai-thresholds-from-a-prospective-real-life-study/