Comparative effects of probiotic supplementation and high-intensity interval training on functional disability in non-radiographic axial spondyloarthritis: A pilot randomized controlled trial

Background Non-pharmacological therapies are often used for the management of axial spondyloarthritis (axSpA). This randomized controlled trial aimed to investigate the effect of probiotic supplementation, compared with high-intensity interval training (HIIT), in patients with non-radiographic axSpA. Materials and methods Individuals with non-radiographic axSpA were recruited and allocated to a probiotic supplementation group or to an online-delivered strength training program for 12 consecutive weeks. The online program was delivered synchronously in small groups under professional supervision. The primary outcome was functional disability, assessed with the Bath Ankylosing Spondylitis Functional Index (BASFI). Secondary measures included disease activity (the Bath Ankylosing Spondylitis Disease Activity Index), spinal mobility (the Bath Ankylosing Spondylitis Metrology Index, and the Ankylosing Spondylitis Quality of Life Questionnaire). Measures were collected one week before randomization (baseline) and at 6, 12, and 24 weeks after baseline. For statistical analysis, a linear mixed model for repeated measures was used. Both statistical significance and clinical relevance (based on MCID thresholds) were analyzed. Analyses were conducted under the intention-to-treat (ITT) principle. Results Twenty patients were initially included. Of those, 8 participants discontinued intervention. No adverse events were reported. There was a non-significant time effect or time*group interaction for the mean changes in the BASFI score after baseline. Lack of significant differences between groups was observed for the secondary measures. However, more than half of participants in both groups achieved clinically relevant improvements in the BASFI score at follow-up assessments. Conclusion These preliminary results should be interpreted with caution, as they are exploratory and hypothesis-generating rather than confirmatory. Both interventions showed potential benefits but require further testing in larger, adequately powered trials.