Long-term benefits of radon spa therapy in rheumatic diseases?

There has been a study in a publication called Rheumatology international concerning radon spa therapy. Exposure to radon is still used in Germany and Austria. The spa owners tell us that the exposure is without health risks, but at the same time we are told by agencies of the government to avoid radon exposure. If the exposure is so low that the risk is negligible, how would it work?

A. and T. Franke published: “Long-term benefits of radon spa therapy in rheumatic diseases: Results of the randomised, multi-centre IMuRa trial”. The randomised, blinded trial enrolled 681 patients in 7 health resorts in Germany and Austria with chronic back pain (n = 437), osteoarthritis (OA) (n = 230), rheumatoid arthritis (n = 98), and/or ankylosing spondylitis (n = 39); multiple nominations in 146 cases. Result showed: “Until end of follow–up, superiority of radon therapy was found regarding pain relief (p = 0.032) and analgesic drug consumption (p = 0.007), but not regarding quality of life.” “Significant benefits were found in radon–treated OA patients until 6–month follow–up (p = 0.05), but not until end of study (p = 0.096).” “Neither the back pain sub–population nor the two smaller patient populations with inflammatory indications benefited significantly in functional capacity.”

So, what do we have? We have a small effect on pain and a short term effect on function in some of the treatment groups. But are the groups comparable? As much as apples and pears! The authors tell us: “we investigated radon spa therapy as applied in health resorts compared to a control intervention in rheumatic out-patients.” How about comparing a luxury cruise through the Caribbean with spending the vacation in a backyard? And I still don’t understand how the patients were randomised.

All in all this study does not convince me to recommend radon spa therapy.

Links to other blogposts, but both are in German:
http://rheumatologe.blogspot.de/2012/07/radonstollen-therapie-bei-rheumatischen.html
http://rheumatologe.blogspot.de/2013/05/radonstollen.html