Efficacy of Whole-Body Cryotherapy in Ankylosing Spondylitis: A Systematic Review with Meta-Analysis.

Introduction: Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by pain, stiffness, and progressive joint deformities. While pharmacological treatments remain the standard approach, adjunct therapies like whole-body cryotherapy (WBC) have gained attention for their potential benefits in reducing pain and inflammation. However, the effectiveness of WBC in AS remains unclear. Methods: A systematic search was conducted in PubMed, Scopus, Web of Science, and Embase for studies published up to November 2024. The study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered in PROSPERO (CRD42024620792). Primary outcomes included disease activity (Bath Ankylosing Spondylitis Disease Activity Index [BASDAI], Ankylosing Spondylitis Disease Activity Score [ASDAS]) and pain intensity (VAS), while secondary outcomes assessed function (Bath Ankylosing Spondylitis Functional Index [BASFI]) and inflammation (C-reactive protein [CRP]). Effect sizes were calculated using Cohen's d, with heterogeneity evaluated through Cochrane's Q-test and Tau² variance. Results: Five studies involving 310 patients met the inclusion criteria. Tau-squared was estimated as zero, indicating a common effect size across studies with no dispersion of true effects. Intervention protocols varied in temperature (-60°C to -10°C) and session duration (80 sec to 3 min). WBC significantly improved BASDAI (p < 0.001), ASDAS (p = 0.015), BASFI (p = 0.006), and VAS pain scores (p = 0.005), demonstrating a strong therapeutic effect. However, no significant impact was observed on CRP levels (p = 0.684). Conclusion: WBC significantly improved pain, function, and disease activity in patients with AS. As a promising nonpharmacological adjunct therapy, further research is needed to optimize protocols and evaluate its tolerance and long-term efficacy.