Prospective long-term follow-up of patients with idiopathic environmental intolerance attributed to electromagnetic fields after a provocation trial.

Previous short-term follow-ups of idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) found no patients recovered after receiving provocation trials, and only a small portion were willing to consider something else caused their symptoms, although levels of their symptoms and concerns decreased. Few long-term follow-ups have been conducted, so we conducted a study to fill the data gap. We recruited participants of the initial provocation trial between 2010 and 2015 to assess changes in symptoms and concerns related to EMFs and the reversibility of IEI-EMF. The same questionnaire used in the trial was administered through telephone interviews. Of the 147 participants recruited, 70 completed the follow-up, including 35 IEI-EMF patients and 35 referents. Of the patients, 60 % were willing to consider something else caused their symptoms, and 62.9 % reported recovery from IEI-EMF after the trial in 1.80 years on average, among whom 86.4 % reported idiopathic recovery. Most of the proportions of symptoms and concerns related to EMFs among patients decreased after the trial although changes in concerns between the study groups did not reach significant differences. In conclusion, different from the previous short-term follow-ups, most patients recovered in our long-term follow-up. Most of recovered cases were idiopathic, indicating IEI-EMF is self-limited in most cases given sufficient time. Most of patients were willing to consider something else caused their symptoms, indicating most cases of IEI-EMF might be attributable to nocebo effects. Our findings suggest a possible therapeutic effect of provocation trials, which needs to be confirmed by further randomized controlled intervention studies.