Functional and physiological outcomes in axial spondyloarthritis: comparing biological and non-biological treatment approaches.

Background: Pharmacological treatments have been shown to improve physical and physiological functions in patients with axial spondyloarthritis (axSpA).

Purpose: This study aimed to compare core endurance, exercise capacity, cardiopulmonary responses during exercise testing, quality of life (QoL), and disease activity among patients with axSpA using biological and non-biological treatments, and healthy controls.

Methods: This cross-sectional study involved 52 patients on biological therapy, 57 on non-biological drugs, and 46 healthy controls. Core endurance (McGill tests), exercise capacity (six-minute stepper test), and disease activity indexes (The Bath Ankylosing Spondylitis Disease Indices; BASDAI, BASMI, BASFI, ASDAS-CRP, Leeds Enthesitis Index; LEI), spinal and hip radiographic scores (modified Stoke Ankylosing Spondylitis Spinal Score; mSASSS), Bath Ankylosing Spondylitis Radiology Hip Index; BASRI-hip), pain (Numeric Rating Scale), patient and physician global assessments, cardiopulmonary responses, quadriceps muscle fatigue and dyspnea (Modified Borg scale), laboratory markers (CRP, ESR), and QoL (Ankylosing Spondylitis QoL Scale; ASQoL) were measured.

Results: Step counts in the six-minute stepper test, trunk flexor, and lateral flexor muscle endurance values were significantly lower, while fatigue and quadriceps muscle fatigue during the six-minute stepper test were significantly higher in patients compared to healthy controls (p < .05). BASMI values were significantly lower in the non-biological treatment group compared to the biological group (p < .05). Step counts showed weak correlation with BASMI (r = -0.142; p = .167), moderate-strong correlation with BASDAI (r = -0.458; p < .001), ASQoL (r = -0.450; p < .001), ASDAS-CRP (r = -0.361; p < .001), trunk extensor and flexor muscle endurance (r = 0.489; p < .001, r = 0.485; p < .001), right and left trunk lateral flexor muscle endurance (r = 0.584; p < .001, r = 0.572; p < .001), and BASFI (r = -0.582; p < .001). Step count variance was explained by BASMI, BASDAI, BASFI, ASQoL, and trunk endurance, accounting for 34.1% of the total variance.

Conclusion: These findings may assist clinicians in planning personalized rehabilitation programs by considering not only functional limitations but also treatment history of the patients with axSpA. Understanding the effects of pharmacological treatment history on exercise capacity and core muscle endurance may guide the development of more effective physiotherapy approaches.