Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.


Ankylosing Spondylitis Diasease Activity Score (ASDAS): What Level Corresponds to Low Disease Activity and What Is An Important Improvement?

Lie1,  Elisabeth, van der Heijde2,  Désirée M.F.M., Uhlig1,  Till, Kvien1,  Tore K.

Diakonhjemmet Hospital, Oslo, Norway,
Leiden University Medical Center, Leiden, Netherlands

Purpose:

ASDAS is a newly developed ASAS endorsed disease activity score calculated from BASDAI questions 2, 3 and 6, patient global assessment, and CRP. Cut-points for ASDAS states and changes as well as response criteria based on the ASDAS are not yet established. Our objective was to examine how ASDAS relates to patient acceptable symptom state (PASS), minimal clinical important improvement (MCII) and levels of/changes in physician global assessment (PhGA).

Methods:

AS patients were extracted from a multi-center treatment registry where patients (pts) with inflammatory arthropathies starting treatment with DMARDs and biologicals are followed longitudinally. 448 pts (69% male, 89% HLA-B27 pos, biologicals n=340, DMARDs n=66) were included in the baseline analyses while 243 pts had 3-month follow-up data. Patients were at each time point asked if they were in a satisfactory condition (yes/no), i.e. PASS, and pts were from 3 months onward asked if they had experienced a considerable improvement since start of therapy (yes/no), i.e. MCII. ASDAS levels/changes were examined across disease states and level of changes defined by PASS, MCII and PhGA (0–10 cm VAS). We performed receiver operating characteristic (ROC) curve analyses (maximum accuracy and 80% specificity approaches) to find cut-offs for ASDAS.

Results:

At treatment start (baseline) mean(SD) ASDAS were 3.51(1.01) and 3.28(0.97) for pts on biologicals and pts on DMARDs, respectively, while mean(SD) 3-month changes were -1.31(1.24) and -0.31(0.97). 28%/58% of pts were in PASS at baseline/3 months, while 65% reported an important improvement on therapy. Among pts reporting/not reporting PASS at baseline and 3 months mean(SD) ASDAS were 2.96(0.95)/3.72(0.97) and 1.84(0.91)/3.00(1.14), respectively. Mean(SD) 3-month DASDAS were -1.71(1.07)/-0.20(0.97) in pts reporting/not reporting significant improvement, and -1.85(1.15)/-0.59(1.06) for pts with DPhGA <=-2/>-2, respectively. The results of the ROC analyses are shown in the table.

ROC analyses – ASDAS cut-points for state and change

ASDAS state80% spec.Max. accuracyAUC (95% CI)
Baseline PASS yes (vs. no)2.963.150.71 (0.65–0.77)
3-month PASS yes (vs. no)2.012.500.79 (0.74–0.84)
Baseline PhGA <4 (vs. >=4)3.053.400.70 (0.65–0.75)
3-month PhGA <4 (vs. >=4)3.553.550.92 (0.88–0.96)
ASDAS change   
3-month MCII yes (vs. no)-0.88-0.680.86 (0.81–0.91)
3-month DPhGA <=–2 (vs. >-2)-1.40-1.270.79 (0.73–0.85)
3-month DPhGA <=-4 (vs. >-4)-2.00-1.530.80 (0.73–0.88)

Conclusion:

In this study, PASS corresponded to ASDAS levels of 2.01 to 3.15 depending on time for assessment and method. The ASDAS levels corresponding to PASS were considerably lower at baseline than at 3 months. MCII corresponded to DASDAS of -0.7 to -0.9 while >2 point improvement of PhGA corresponded to a larger ASDAS change. These data show how ASDAS relates to PASS, MCII and the PhGA, but further work is needed to define cut-points for ASDAS change and states.

To cite this abstract, please use the following information:
Lie, Elisabeth, van der Heijde, Désirée M.F.M., Uhlig, Till, Kvien, Tore K.; Ankylosing Spondylitis Diasease Activity Score (ASDAS): What Level Corresponds to Low Disease Activity and What Is An Important Improvement? [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1796
DOI: 10.1002/art.26870

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