Unlike some earlier studies based on detailed information from questionnaires or interviews, we have no detailed information on the actual level or frequency of the occupational exposure.
However, one study compared the expert-assessed likelihood of pesticide exposure based on detailed, individual-specific questionnaire and job-specific module interview information with reported farm-related job titles as a surrogate for pesticide exposure.
Diagnosis was based on detailed clinical and laboratory evaluation.
The present analysis is based on a detailed second questionnaire sent six months later to baseline questionnaire respondents, which was completed by 334,908 individuals.
Based on self-reported detailed questionnaire, all the subjects considered themselves as healthy, they had no other environmental exposures (second hand smoke, pollutants or asbestos fibers) [ 5].
Based on self-reported detailed questionnaire all subjects were symptom-free and considered themselves as healthy, they had no other environmental exposures (such as second hand smoke, pollutants or asbestos fibres) [ 28].
Design: Independent categorization (based on questionnaires; for 15 persons, questionnaires plus personal interviews) by 2 investigators.
The headache survey was performed by means of an interview based on a detailed pretested structured assessment questionnaire.
