Department of Biostatistics, Washington University, St. Louis, MO 63112
A recent article by Kozlowski et al. (1) investigated the feasibility of using random digit dialing to obtain DNA samples from people after they were asked about their smoking behaviors. Their study consisted of 3,383 White, Black, Asian, and other subjects. Each was interviewed and, upon consenting to participate, was mailed information about the study. Those willing to take part were also mailed a buccal-sample collection kit, and DNA collected by using these kits was returned. These samples were then randomly placed into one of two groups, the "registry" group or the "made-anonymous" group. The DNA was genotyped, and the data obtained by collecting this DNA were analyzed by using multiple logistic regression. The analysis suggested evidence for the feasibility of gathering DNA by using random digit dialing.
Although these authors (1) specified that their purpose was to determine the feasibility of this type of study, I have some biologic and behavioral inquiries concerning the results. For instance, there was no talk about the error associated with obtaining DNA. Even though cheek cells are very specific and can be easily identified by a trained researcher, I am not convinced that contaminated or faulty DNA should not be accounted for. The article mentioned that 26 percent of the interviewees returned buccal swabs but that only 18 percent were successfully genotyped. What happened to the missing 8 percent of the samples?
In addition, there was no mention in this article (1) about what could have been done to improve response and return rates. Did the time of day that these people were interviewed play a role in their willingness to take part in the study? Would adding a question as to why people did not want to be involved in this study have led to important information for improving rates in future studies? In modern genetic and/or behavioral studies, it is common to use questionnaires with a large number of items for acquiring as much about the subject as possible. Would a more in-depth questionnaire have resulted in lower DNA return rates? Overall, I am convinced of the feasibility of using random digit dialing to obtain DNA, but I would like to see how these results compare to a follow-up study in which more confounding factors are explored.
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