Symptoms of chronic solvent encephalopathy: Euroquest questionnaire study

The aim was to study the symptomatology of chronic solvent encephalopathy (CSE), and the persistence of the symptoms. We examined how Euroquest, a neurotoxic symptom questionnaire, distinguished workers with verified CSE from unexposed employees, and evaluated symptom cut-off for CSE. Another aim was to study the effect of age on the responses. CSE cases confirmed at the Finnish Institute of Occupational Health had completed Euroquest either before their first investigation procedure (CSE-1 group, n=33), or before attending a routine control for previously diagnosed CSE (CSE-2, n=43). Non-exposed carpenters served as referents (n=292). We studied responses to single questions and to symptom domains. The domain with the highest AUC (area under the ROC: Receiver Operating Characteristic Curve) value was chosen to study cut-off points. CSE groups reported nearly all 59 symptoms more frequently than the carpenters. There was only little difference between younger and older carpenters. CSE-1 reported 12 symptoms more often than CSE-2, but no significant differences were found in the memory and concentration domain, which had the highest AUC, above 0.9. Using a three out of 10 symptoms cut-off point, 97% of the CSE-1 cases and 80% of the carpenters were classified correctly. At a four-symptom cut-off, the sensitivity was 93% and specificity 87%. The memory and concentration as core symptoms distinguished CSE cases from unexposed workers and remain, even after cessation of exposure. The effect of age on Euroquest was minor. Euroquest is recommended for the screening of CSE in solvent-exposed work-force and in the diagnostic process of CSE. We propose three memory and concentration symptoms as cut-off to minimize under-detection.