Results. The two groups showed a similar baseline situation. After completion of treatment, relevant clinical improvements were observed in both groups, with no notable group differences. However, the follow‐up revealed sustained effects in the radon arm, and a return to baseline levels in the sham arm. After 6 months, marked between‐group differences were found for both end‐points (pain intensity: −16.9%, 95% confidence interval −27.6 to −6.2%; AIMS score: 0.57, 95% confidence interval 0.16 to 0.98). The between‐group differences were statistically significant for both overall means (pain intensity, P = 0.04; AIMS, P = 0.01).
Conclusion. Marked short‐term improvements in both groups at the end of treatment may have masked potential specific therapeutic effects of radon baths. However, after 6 months of follow‐up the effects were lasting only in patients of the radon arm. This suggests that this component of the rehabilitative intervention can induce beneficial long‐term effects...