The study aimed to investigate effects of radon (plus CO2) baths on RA in contrast to artificial CO2 baths in RA rehabilitation.

134 patients of an in-patient rehabilitative programme were randomly assigned to the groups. Outcomes were limitations in occupational context/ daily living (main outcome), pain, medication, etc. measured before start, after end of treatment, and up to a year thereafter.

Superiority of radon treatment was found regarding reduced limitations in daily living until 12 months after end of treatment. Steroid consumption and NSAIDs were significantly reduced.

Objective: To replicate former observed beneficial effects of Radon (plus CO2) baths on RA in contrast to artificial CO2 baths and to investigate its long-term effectiveness and impact on drug consumption.

Methods: Randomised double-blinded trial with 2 randomised balanced groups enrolling 134 patients of an in-patient rehabilitative programme (a 3rd non-randomised group of 73 consecutive patients is not reported here). Outcomes were limitations in occupational context/ daily living, pain, functional capacity, morning stiffness and medication measured before start, after end of treatment, and quarterly in the year thereafter. Repeated-measures analysis of covariance (RM-ANCOVA) of intent-to treat population was performed to investigate treatment effects. Hierarchically ordered hypotheses ensured adherence of the nominal significance level and allowed examining of long-term effects. Starting with all measures until 6 months' follow-up, significant main effects for group allocation (GME) or significant group x course-interactions (GxC) were regarded essential to add the next follow-up for analysis.

Results: Radon treatment resulted in significantly lower limitations of daily living over at least 9 months whereas reference patients returned to baseline level after 6 months already (RM-ANCOVA until 6 months: pGME=.15, pGxC=.016/ 9 months: pGME=.11, pGxC=.025/ 12 months: pGME=.17, pGxC=.033). Furthermore, consumption of steroids and NSAID was remarkably reduced in the Radon group (RM-ANCOVA until 12 months: for steroids pGME=.064, interaction pGxC=.025, maximum difference after 12 months; for NSAID pGME=.035, interaction pGxC=.008, maximum difference after 9 months).

Conclusion: Results suggest beneficial long-term effects of Radon baths as adjunct to a multimodal rehabilitative treatment of RA.

Inclusion Criteria:

• Rheumatoid arthritis according to the 1987 revised ACR criteria for RA

Exclusion Criteria:

• current exacerbations of the inflammatory process
• other systemic inflammatory diseases
• concomitant musculo-skeletal diseases possibly interfering with outcome measurement,
• pregnancy or breast feeding
• disorders of the central nervous system
• a known tendency toward thrombosis
• malignant hypertension
• coronary heart disease
• heart failure, arrhythmia
• severe disorders of lungs, kidneys, or liver
• advanced malignancies
• abuse of alcohol or drugs,
• major skin lesions,
• severe fever, or infections.