Background/Purpose: In patients with axial spondyloarthritis (axSpA) physical functioning is frequently impaired. The current gold standard to assess physical functioning is self-reported questionnaires (i.e. BASFI), which, however, are of subjective nature. Therefore, a performance-based test-battery was designed to measure physical functioning more objectively: the ankylosing spondylitis (AS) performance index (ASPI)) [1]. To imitate activities of daily living (ADL), tasks based on BASFI domains, were designed. Although the ASPI had previously been evaluated, a thorough analysis of the deficits of physical functioning and factors which influence the performance of patients with axSpA has not been performed to date.

Methods: Consecutive patients diagnosed with axSpA fulfilling the ASAS classification criteria underwent standardized assessments concentrating on the following variables: patient and disease characteristics, patient-reported outcomes (ASDAS, BASFI, BASMI, ASAS Health Index (ASAS HI), PHQ-9, IPAQ), mSASSSand ASPI (ASPI 1: Bending, 2. Putting on socks, 3. Getting up from the floor) [1]. Performance was measured in seconds as time to complete a task based on published instructions given to the patients. Impairment in physical performance was defined as the inability of patients to perform ≥ 1 ASPI test. Spearman Rho correlation was used to compare self-reported functioning and performed physical functioning. Logistic regression analysis was used to identify factors associated with impaired physical performance.

Results: A total of 200 patients (AS 66%, nr-axSpA 34%) was included: 69% males, 44.3±12.5 years old, mean symptom duration 17.9±12.6 years, BMI 27.2±5.5, mean ASDAS 2.5±1.1, BASFI 4.0±2.7, BASMI 3.5±1.8, ASAS HI 7.0±4.1, PHQ-9 8.8±6.2, and mSASSS(n=157) 10.2±18.8. 133 patients were treated with bDMARDs (66.5%). In total 44 patients (22%) were not able to perform one or more ASPI tests. The mean time for bending was 18.6±9.5 sec (n=179/90%), for putting on socks 12.8±6.4 sec (n=156/78%), and for getting up from floor 6.5±5.0 sec (n=187/94%). A significant correlation was found for all three ASPI-tests with BASFI (0.5-0.7), ASAS HI (0.4-0.6). Self-reported physical activity (IPAQ) correlated weakly with ASPI (all 0.2) and structural damage correlated only with the task putting on socks (r=0.3), whereas the other tests did not correlate. Logistic regression showed an influence of obesity, spinal mobility and global functioning on actual performance but not of disease activity and self-reported physical function (Table 1)

Conclusion: This study confirms a good correlation of the ASPI with standard questionnaires of physical functioning and disease activity. However, the ASPI showed a substantial floor effect, since 22% of patients were unable to perform the tests. This striking finding strongly suggests that more information on the actual performance of patients with axSpA is needed. Our data confirm that self-reported physical activity cannot be used as a substitute for the actual performance of axSpA patients. Moreover, obesity as a potential modifying factor that definitely contributes to limitations in actual performance should also be more carefully addressed in patients with axSpA.

Abstract_ASPI_tab1

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analysing-impairments-in-physical-performance-as-assessed-by-the-as-performance-index-aspi-in-patients-with-axial-spondyloarthritis-axspa/