Sustained Improvements in EQ-5D Utility Scores and Self-rated Health Status in Patients With Ankylosing Spondylitis After Spa Treatment Including Low-dose Radon

Background: Patients with ankylosing spondylitis (AS) have significantly lower quality of life (QoL) than the general population. Holistic interventions addressing QoL include spa- or balneotherapy. Inclusion of radon in spa-therapy treatments is beneficial in reducing pain and shows promising results in improving QoL in AS-patients. We aimed to explore the association of spa therapy including low-dose radon with systematically monitored QoL in AS-patients over an extended timeperiod. Methods: Registry data collected for the “ Radon indication registry for the assessment of pain reduction, increase of quality of life and improvement in body functionality throughout low-dose radon hyperthermia therapy ” in the Austrian Gastein valley comprising data on QoL (EuroQol EQ-5D) directly before the treatment (baseline), directly, 3; 6 and 9 months after the treatment, age, sex and body mass index (BMI) were analysed. Two linear regression models explored the association between time of measurement with 1) EQ-5D utilities and 2) EuroQol visual analogue scale (VAS) score. Alterations of 0.05 (utilities) and 5.00 (VAS) were considered clinically relevant. Results: Two-hundred-ninety-one AS-patients were included in the analyses. Forty-four percent (n=128) were women, the mean age was 52 (SD 10) and the average BMI was 26 (SD 4). Utilities and VAS were significantly higher at all timepoints compared to baseline. Improvements were clinically relevant at all timepoints in case of the EQ-5D VAS and until 6 months after treatment for the utility index. Conclusion: Spa therapy including radon results in significant and clinically relevant improvements in Qol of AS-patients until 6-9 months after treatment.