Repeatability of self-reported data on occupational exposure to particular compounds.

The repeatability of self-reported occupational exposure to eight particular compounds was investigated in 209 males aged 49-87 years. The subjects completed an initial mailed questionnaire and were interviewed by telephone 3-5 weeks later. The study was carried out as part of a case-referent study on the relation between occupation and prostate cancer. The repeatability of answers was found to be better in the case of some agents than in that of others: kappas calculated as a measure of concordance range from 0.36 to 0.70. No substantial influence was found to be exercised by age or socioeconomic status, or by case or referent status. Although the repeatability observed was not flawless, it was concluded that self-reported exposure data would appear to be a sound basis for epidemiological studies on the aetiology of disease, whenever objective information on occupational exposure is not available.