We read with great interest the paper entitled “A brief history of spa therapy” by van Tubergen and van der Linden in the March edition of the Annals.¹ Spas have certainly played an important part throughout the centuries not only in recreation but also in restoring physical and mental health. In fact, several spa doctors have greatly influenced the progress of rheumatology—for example, Bruce from Scotland described polymyalgia, Forestier introduced gold treatment for rheumatoid arthritis in France, and Sitaj and Zitnan from Piestany described polyarticular chondrocalcinosis.

We regret that this paper failed to mention the famous spas of the Czech Republic, Slovakia, Hungary, and Romania. From their conception, Czech and Slovak spas became gathering places not only for aristocrats but also for kings and emperors. Hungary, one of the richest countries of thermal waters in the world, has a bath culture dating back to the pre-Roman Celtic times. Budapest is a capital unique for its thermal waters. It is also renowned for Lake Hévíz, the second biggest hot lake in the world, second to Rotorua, New Zealand.

We are proud to have published in English the first double blind controlled trials with thermal water treatment.² Hungary is the only country where medical use of thermal waters is practised based on its efficacy proved in controlled trials.

We profoundly disagree with the authors, that “taking the water, balneotherapy, spa therapy, hydrotherapy are more or less interchangeable”. We are certain that they are not. Even in their paper, they quote Priessnitz and Kneipp, who distinguished between thermal water (balneotherapy) and hydrotherapy.¹ Hydrotherapy uses only the physical qualities of water (buoyancy of water, resistance, sometimes its temperature either cold or warm), whereas thermal waters are not only naturally warm (>20°C) but their mineral content is also significant. In Hungary a recognised mineral water should have minerals 1 g/l or more, but no nitrites, nitrates, or bacterial growth. It is not known whether the minerals of mineral water penetrate the body surface, but they are known to cause a so-called spa or mineral water reaction.² The mineral water reaction includes tiredness and fatigue especially after 5–8 bathes with an associated rise in the leucocyte count and erythrocyte sedimentation rate even within the normal range. The mineral water reaction passes away after 5–10 bathes, and the optimal “taking the waters” is a total of 15–22 bathes taken daily.

There is no equation between thermal mineral waters and spa therapy either. As we pointed out in a debate in the columns of the Journal of Rheumatology^3–5 the effect of thermal mineral waters and the effect of complex spa therapy should be distinguished. We performed our double blind trials on inhabitants of ordinary Hungarian towns and villages with no spa facilities to exclude the placebo effect of a change in environment, physiotherapy, and being in a holiday atmosphere. In spa surroundings no double blind trials can be done. The results of follow up of these subjects suggest that non-spa treatment can be used as a control for future studies. Furthermore, the effect of spa water and heated tap water can be used for local residents to exclude the placebo effect of spa atmosphere, associated physiotherapy, etc. If we really want to have evidence based proof for thermal mineral water or spa treatment, or both, we should keep strictly to these rules.

We agree that spa resorts are excellent places for the rehabilitation of patients with rheumatic diseases, especially ankylosing spondylitis. In addition, rehabilitation treatments are available for patients with fibromyalgia, a group who are frequent users of spa facilities. Most of the German, Czech, Slovak, Hungarian, and Russian spas also function as rehabilitation centres. In Hungary, thermal mineral water and spa treatment is a recognised treatment for rheumatic patients, although hard data are lacking. The Hungarian government has launched a 10 year spa programme for the development of Hungarian spas. In addition, the Hungarian National Activity Network of the Bone and Joint Decade was given the task by the minister of health to start evidence-based research about the effect of mineral water and spa treatment. Hungary organises the 34^th World Congress of the International Society of Medical Hydrology and Climatology at Budapest and Hévíz in October this year. Attendance by rheumatologists and rehabilitation experts is expected.

We feel it is time to create European co-operation in rheumatology spa and mineral water research. We are convinced that multicentre trials would be valuable despite differences in mineral concentration, temperatures, cultures and beliefs. Underdevelopment of evidence-based physiotherapy is partly due to lack of funding for necessary trials. The situation is similar for balneotherapy and spa treatment trials. This problem may be overcome by conducting multicentre trials in many countries. Such trials may result in an evidence-based approach to therapeutic or recreational bathing.