RELIABILITY OF PASSIVE SMOKE EXPOSURE HISTORIES IN A CASE-CONTROL STUDY OF LUNG-CANCER

Despite the growing number of studies on the health effects of passive smoke exposure, few data exist on the quality of questionnaire data o n passive smoking. To measure the reliability of passive smoking histo ries, re-interviews were conducted for 110 subjects (37 cases and 73 c ontrols) as part of a larger study of lung cancer among non-smoking wo men in Missouri. Agreement was high both for parental smoking status ( 94% concordance; kappa = 0.82) and for spousal smoking status (84% con cordance; kappa = 0.67). Concordance also was relatively high for ciga rette pack-years of exposure due to the parents or spouse. Reliability tended to be somewhat higher among controls than among cases, and for exposure due to a parent or spouse than for that due to other househo ld members. Questions on the perceived harmfulness of passive smoke ex posure showed no differences between cases and controls. These finding s indicate a high degree of repeatability in responses regarding passi ve smoking, but also suggest the potential for misclassification of pa ssive smoke exposure status, the desirability of standardized question s on passive smoking, and the need for additional studies of reliabili ty and validity.