Spanager L (2005). Jansen’s 1910 use of a single blind experiment to assess the effects of radioactive water on rheumatic diseases.
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© Lene Spanager, Bakkedraget 18, 2nd floor, DK- 3400 Hillerød, Denmark. Email: lenspa02@heh.regionh.DK

Cite as: Spanager L (2005). Jansen’s 1910 use of a single blind experiment to assess the effects of radioactive water on rheumatic diseases. JLL Bulletin: Commentaries on the history of treatment evaluation (

In 1910 Jansen published his study on the treatment of arthritis using radioactive water. He observed what seemed to be a favourable response, but he was aware that he needed to consider several alternative possible explanations for his observations: the results might have occurred by chance, they might have reflected the patients’ suggestibility, and they might have been caused by concomitant factors, such as hospital admission, bed rest and diet.

He felt certain that he could exclude the first of these factors – chance – because of “the constancy with which [the reactions] occurred and because the timing of the improvements seen in a number of patients were related to the treatment in such a way that it would be far fetched to regard them as having occurred by chance.”

He admitted that the third factor – hospital admission, for example – might be significant, but he tried to reduce its impact, partly by delaying treatment “until the patients had already been in hospital for a period of time and until they had received other treatments with unsatisfactory results,” and partly by treating out-patients as well.

Although Jansen did not use a parallel control group, he did try to address suggestibility and prevent biased reports of symptom relief by ‘blinding’ some of the patients to the true nature of the treatment and by administering placebo to others. He tried to minimize the impact of suggestion by providing patients with different explanations of the nature of the treatment. To some he suggested that it was a new treatment, something like a “new tasteless Aspirin”. In others he first gave the patient distilled water and then, without letting the patient know when, administered the radioactive water. No ‘blinding’ of the investigator was mentioned, either because Jansen did not regard this as important, or because he had not thought of this possibility.

The source of Jansen’s inspiration for these methodological precautions is not reported, which is a pity because ‘blinding’ and placebo treatment were rare at the beginning of the 20th century. Neither his fellow countrymen Finsen or Fibiger had used blinding in their assessments of light treatment for lupus vulgaris and serum treatment for diphtheria, respectively (Finsen 1896; Fibiger 1898).


Finsen NR (1896). Om Anvendelse I Medicinen af koncentrerede kemiske Lysstraaler. Kjøbenhavn: Gyldendalske Boghandels Forlag.

Fibiger J. (1898) Om serumbehandling af difteri [On treatment of diphtheria with serum]. Hospitalstidende 6:309-325

Jansen H (1910). Behandling med Radiumemanation særlig ved gigtiske Lidelser. [Treatment with radium emanation especially with rheumatic diseases]. Ugeskrift for Læger 72:1333-48.