Euroquest: the validity of a new symptom questionnaire

The new questionnaire Euroquest was designed to study effects from exposure to organic solvents, and it covers the most commonly reported symptoms associated with long-term solvent exposure. Its convergence and criterion validity were evaluated by means of comparison with the two well-established generic symptom questionnaires Symptom Checklist (SCL-90) and General Health Questionnaire (GHQ-30). Men with long-term exposure to organic solvents and symptoms common in toxic encephalopathy (TE) classified as TE type 2A (n=29) or 2B (n=28) according to their neuropsychological test performance, and a comparable group of non-exposed healthy referents (N=57), were included. The six Euroquest factors obtained by a factor analysis were labeled: 'emotional lability' 'cognitive disturbances' 'peripheral neurology' 'sleepiness' 'fatigue' and 'sleep disturbances'. These factors correlated well with most SCL-90 scales and with the GHQ-30 total score in the combined TE groups. The combined TE groups were correctly classified to a similar degree by the Euroquest factors 'cognitive disturbances' and 'peripheral neurology' (TE 82.5% and referents 93%) and the SCL-90 scales 'somatization, 'interpersonal sensitivity', 'obsessive-compulsive symptoms' and 'hostility' (TE 84.2% and referents 93.0%), but not as well by GHQ-30 (TE 61.4% and referents 79%). In comparison with the separate TE groups most referents, and a considerably higher percentage of 2B than 2A subjects, could be correctly classified with both Euroquest and SCL-90. With GHQ-30, only a few 2A cases and fewer than half of the 2B cases were correctly classified. In conclusion, the Euroquest factors converged with both SCL-90 scales and GHQ-30 score. With both the Euroquest and SCL-90 questionnaires a similar percentage of the TE subjects were discriminated from the referents, most conspicuously regarding TE 2B subjects, who had an objectified cognitive dysfunction. In a choice between Euroquest and SCL-90, the Euroquest may have the advantage of higher face validity, for TE subjects.