Abstract
The pilot phase is reported of a case-control study to determine risk factors for severe CFS/ME. One hundred fifty-seven members of the ME Association, selected at random, were sent postal questionnaires, with a 56% response. The Barthel index was used as a validated proxy measure to distinguish severe disease (cases) and those less severe. Thirteen of 88 respondents had severe disease, and 44 mild disease. Two matched controls from the ‘mild’ group were selected per case. Of possible risk factors, odds ratios greater than 2 were found for comorbidities, damaging initial treatment and occupational chemical exposure, although in this study they were not statistically significant. These data suggest that additional studies are warranted.