Reproducibility of the University of Toronto self-administered questionnaire used to assess environmental sensitivity

Environmental sensitivity patients report symptoms provoked by low-level exposure to a wide range of substances. Features of published case definitions include nature of onset, chronicity, symptom provocation by multiple substances, symptom provocation by an escalating number of exposures, involvement of multiple body systems including the nervous system, provocation by unrelated substances, and addictive behaviors. This study assessed the reproducibility of a Canadian self-administered questionnaire, the University of Toronto Health Survey, designed to determine the prevalence of the features described in these case definitions. A total of 191 eligible respondents aged 16-70 years who attended several types of medical practices in 1994 were invited to complete a second questionnaire 5-7 months after the first; 134 (70.2%) complied. Total agreement on whether patients satisfied each of seven case definitions ranged from 80% to 90%. After adjustment for chance, major agreement was observed for three of the seven case definitions (kappa = 0.69, 0.68, and 0.78). The survey achieved good reproducibility regarding self-report of symptoms described in published case definitions of environmental sensitivity.