Background: A multidisciplinary approach and a multi-modal methodology are needed to assess idiopathic environmental illnesses.
Sample: 61 patients took part in all diagnostic steps.
Method: In the Basel pilot research project on environmental illness, a threefold diagnostic approach was established: patients had a medical and allergological examination, a psychiatric and psychological exploration and an environmental analysis of their homes.
Results: There is a clear psychological impact on environmental illness: 46 % of the symptoms could be traced back to psychological factors, and 18 % seemed to be influenced by them. Nevertheless, in 28 % more than one of the three dimensions was seen as important. Values within the self reporting questionnaires show high correspondence. Whereas patients and experts agree in many instances that there are psychological factors, they disagree in attributing clinical relevance to them. This discrepancy is helpful for explaining the difficulties therapists may encounter as to the patients' compliance.
Consequences: Environmental illness should be diagnosed and treated on an interdisciplinary basis including psychosomatic medicine.