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Children With Asthma: Study Participation and Generalization of the Results

Wilson et al reported that maternal smokers were less likely than nonsmokers to enroll in an asthma education research study and, if enrolled and randomized to the intervention, were less likely to attend education sessions than were nonsmokers. We observed here that children whose families did not comply with the follow-up assessments had greater baseline ETS exposure than those who were retained but were no more likely to have a maternal caregiver who smoked (children with cotinine data at follow-up, 47%; children without cotinine data at follow-up, 50%). We could not determine whether children whose parents declined to participate in the study at all may have had still greater exposure than did participants, because we lacked the necessary data on nonparticipants. The results of any intervention study that recruits nonvolunteers (ie, individuals who were not identified by virtue of their seeking assistance with ETS reduction or smoking cessation) necessarily generalize only to those willing to participate. It is likely that those who are contemplating or willing to contemplate making changes in smoking practices are more likely to participate in such a study than those who are at a precontemplation stage, hence the results of the experiment may generalize only to the former population. canadian neighborhood pharmacy

In the case of smokers in particular, there is apparent resistance to participation in such research. Some families may have been sensitized to the issue of passive smoke exposure in previous contacts with the health-care system. One parent who did participate feared that continuing to expose the child to ETS might result in intervention by Child Protective Services. Given these concerns and the increased concentration of smokers in lower-income and lower-education populations, the rates of participation and retention in the present study are not surprising. They mirror the experience in other studies recruiting nonvolunteer subjects into smoking cessation programs and recruiting low-education populations into research in general. Our participation rate of 31%, for example, is only slightly lower than that of Irvine et al (47.9%), who recruited a population in Scotland having 16% college graduates for a study with far fewer demands in terms of time and invasiveness. To date, most childhood ETS exposure reduction research predominantly has involved white populations with higher education and income levels, whereas the present sample was predominantly minority, exclusively Medi-Cal-eligible, and resided in an agricultural region experiencing a double-digit unemployment rate. It is likely that special strategies will be needed to move parents who are at a precontemplation stage with regard to smoking cessation or prohibition of smoking in the home to the point of contemplation.