Validity and repeatability of self-reported occupational and industrial history from patients in EEC countries

The results of a study to assess the feasibility and acceptability of a questionnaire designed to ascertain occupational history and the repeatability of coding occupational and industrial status using an abbreviated version of the coding status are presented for EEC countries. The study demonstrates the difficulty of recruiting cancer patients below age 65. The percentage of useful information among patients who completed a self-administered questionnaire was slightly lower than those who completed an administered questionnaire but in general the response rate for most items in the questionnaires in any group was above 90%. The repeatability of coding occupational status and industrial status for current or last job was satisfactory with Kappa values of 65% and 76% respectively. The within-individual repeatability for these variables had similar Kappa values. The validity of coding occupational status with an abbreviated version of coding status compared to the full instructions was satisfactory for current or last occupation. However, observer variability may be fairly large for the abbreviated version. An increase in the coding repeatability could probably be achieved with few modifications to the description of occupation status groups and clearer headings for each division of the Industrial Occupation Classification and greater training of coders.