AB0883 UNSATISFACTORY AEROBIC CAPACITY IS FREQUENT IN AXIAL SPONDYLOARTHRITIS AND LINKED TO WORSE CHEST EXPANSION AND UNHEALTHY LIFESTYLE HABITS – RESULTS FROM A POPULATION-BASED, CROSS-SECTIONAL STUDY
Authors: E. Lindqvist, J. K. Wallman, J. Sagard, T. Olofsson, E. Mogard
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Aerobic capacity (cardiorespiratory fitness) is an established indicator of overall health and low aerobic capacity is an independent modifiable risk factor for cardiovascular disease, morbidity, and overall mortality.(1) Patients with axial spondyloarthritis (axSpA) have an increased risk of cardiovascular disease and although physical activity is part of the treatment, almost half of the patients in a previous report did not meet the required level of physical activity to promote health.(2) <h3>Objectives:</h3> The aim of this study was to assess aerobic capacity in patients with axSpA and to identify factors associated with low aerobic capacity. <h3>Methods:</h3> Patients with clinical axSpA from a defined area of southern Sweden were cross-sectionally examined and thoroughly classified as either nr-axSpA (ASAS criteria; n=74) or r-axSpA (modified NY or ASAS criteria; n=112). Aerobic capacity was examined by a submaximal ergometer test (Åstrand). A level of ≥35 mL O<sub>2</sub> x kg<sup>-1</sup> x min<sup>-1</sup> (mL O<sub>2</sub>) is estimated to be an acceptable level for health, while a level of &lt;35 mL O<sub>2</sub> increases the risk of illness in healthy adults.(1) Other measures assessed were spinal mobility, chest expansion, pain intensity/distribution/sensitivity (by VAS, mannequin and computerized cuff pressure algometry),(3) radiographic changes (sacroiliac joints [SI-joints]/modified Stoke Ankylosing Spondylitis Spinal Score [mSASSS]), lifestyle habits, health-related quality of life, and standard axSpA outcome measures. Logistic regression was used to study disease variables and lifestyle habits associated with a low aerobic capacity (&lt;35 ml O<sub>2</sub>); in a first step adjusting each assessed variable for age, sex and disease subtype (nr- or r-axSpA). Finally, variables with p&lt;0.05 in that first step were assessed jointly in an extended multivariate logistic regression model. ASDAS-CRP and BASFI were assessed in separate, but otherwise identical multivariate models due to multicollinearity. <h3>Results:</h3> Low aerobic capacity indicating a risk for illness was found in 59% of patients. Still 66% of these patients reported a healthy level of physical activity. Patient characteristics are presented in Table 1. Patients with low aerobic capacity were older and more often women, but with no difference between nr- and r-axSpA. Other factors associated with low aerobic capacity − when adjusted for age, sex and axSpA-subtype − were worse ASDAS-CRP, BASFI and chest expansion, as well as higher BMI. In addition, patients with low aerobic capacity had less healthy dietary habits and fewer reached a healthy level of physical activity. Patients with aerobic capacity &lt;35 mL O<sub>2</sub> also had lower pain tolerance, while chronic pain was equally common in both groups. Furthermore, no associations were seen with grade of radiographic changes, global health, pain, fatigue, health-related quality of life or DMARD treatment. In the multivariate analyses, apart from age and sex, only chest expansion, BMI and lower level of physical activity remained significantly associated with worse aerobic capacity. (Figure 1) <h3>Conclusion:</h3> A majority of patients with established axSpA displayed an aerobic capacity indicating a high risk for morbidity. Low aerobic capacity was linked to worse chest expansion and lifestyle factors such as higher BMI and lower physical activity level, both modifiable cardiovascular risk factors. These findings emphasize the importance of assessing aerobic capacity in standard clinical practice and to actively promote and support patients with axSpA to achieve a healthy lifestyle. <h3>REFERENCES:</h3> [1] <i>Ross. Circulation. 2016;134:e653–e699</i> [2] <i>Mogard. BMC Rheumatol. 2022;6:29</i> [3] <i>Mogard. J Rheumatol. 2021;48:1672–9</i> <h3>Acknowledgements:</h3> We thank all the patients and staff involved in the SPARTAKUS study. A special thanks to our research nurses Miriam Walsh-Ingelström and Ellen Landgren. <h3>Disclosure of Interests:</h3> Elisabet Lindqvist: None declared, Johan K Wallman AbbVie, Amgen. Not related to this work, AbbVie, Amgen, Eli Lilly, Novartis, Pfizer. not related to this work, Jonas Sagard: None declared, Tor Olofsson Merck/MSD, UCB. Not related to this work, Elisabeth Mogard Abbvie/abbott, Novoartis, Not related to this work.