Background In most clinical trials response to anti-TNF therapy is based on the ASAS20% response criteria (ASAS20) . The ASAS20 is based on self-reported questions on physical function (Bath AS Functional Index, BASFI ), disease activity, and a pain and a global patient assessment. However, self-reported measures can be influenced by over- or underestimation. In an effort to find more objective outcome measures, eight performance-based tests were developed based on items of the BASFI. The tests provided information on physical functioning in addition to the BASFI and showed improvement in ASAS20 non-responders after anti-TNF therapy. However, performing all eight tests might be cumbersome in daily clinical practice.
Objectives To find a limited set of quick and easy applicable performance-based tests for daily clinical practice that are reliable and reflect improvement in physical functioning after anti-TNF therapy in ASAS20 non-responders.
Methods A test-retest design was used to evaluate reliability (n=65). A longitudinal design was applied to evaluate improvement in performance-based physical functioning after three months of anti-TNF therapy (n=82). The tests that showed an adequate reliability and the largest proportion of patients with an improved performance-based physical functioning were selected. These tests were combined into a new criterion for improvement in physical functioning (AS Performance-based Improvement, ASPI). The ASPI was used to establish the proportion of patients with an improved physical functioning that might be missed by using the ASAS20 response.
Results Reliability for all tests was adequate to excellent (ICC’s 0.73 - 0.96). The tests for bending, putting on socks and getting up from the floor showed the largest proportion of improved patients. The combination of these three test showed improved physical functioning in 73% of the ASAS20 responders (i.e. n=40/82= 49% total group) and 56% of the ASAS20 non-responders (i.e. n=15/82 =18% total group). For these tests only a stopwatch, 15 minutes of time, a shelf or table, six pens, a pair of socks, a chair and mat are necessary.
Conclusions The tests for bending, putting on socks and getting up from the floor are recommended for use in daily practice, because they are reliable, quick and easy to perform. Moreover, the combination of these tests (i.e. ASPI) showed an improved physical functioning after TNF therapy in 56% of the non-responders (i.e. 18% total group). The ASPI might have an important additional value next to the ASAS20 in the evaluation of the effect of anti-TNF treatment.
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Disclosure of Interest None Declared