Sustained improvements in EQ-5D utility scores and self-rated health status in patients with ankylosing spondylitis after spa treatment including low-dose radon – an analysis of prospective radon indication registry data

Abstract

Abstract Background Patients with ankylosing spondylitis (AS) have significantly lower quality of life (QoL) than the general population. Holistic interventions addressing QoL comprise spa- or balneotherapy including radon. These interventions have shown to be beneficial in reducing pain and improving QoL in AS-patients. We explored the association of spa-therapy including low-dose radon with QoL in AS-patients over an extended time period. Methods Registry data collected for the “Radon indication registry” in the Austrian Gastein valley comprising data on QoL (EuroQol EQ-5D) directly before the treatment (baseline), directly(t1), 3 (t2); 6(t3) and 9(t4) months after the treatment, age, sex and body mass index (BMI) were analysed. Linear regression models explored the association of measurement time with 1) EQ-5D-5L 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 (t1: 0.09 [0.07;0.11]; t2: 0.08 [0.06; 0.10]; t3: 0.06 [0.05;0.09]; t4: 0.04 [0.02;0.06]) and VAS (t1: 11.68 [9.38; 13.97]; t2: 12.20 [9.78; 14.61]; t3: 9.70 [7.24; 12.17]; t4: 6.11 [3.57; 8.65]) were significantly higher at all timepoints compared to baseline. Improvements were clinically relevant at all timepoints in case of the VAS and until 6 months after treatment for the utilities. Conclusion AS-patients who received spa therapy including radon show significantly and clinically relevant improvements in Qol until 6–9 months after treatment.