Mohammad Solati - Dental student, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
Farzaneh Boroumand - PhD in Biostatistics, Research Fellow and Biostatistician, University of Sydney, Sydney, NSW, Australia.
Hediyeh Toutouni - Community Oral Health Dept., School of Dentistry, Mashhad University of Medical Sciences

AbstractBackground: A representative sample in health surveys ensures the findings can be reliably generalized to the target population. Conducting oral health surveys through telephone interviews has become more common, and ensuring respondent randomness is necessary for any health survey. Several techniques have been suggested. This paper reports applying the last-birthday method as a within-household random selection method for the first time in an oral health telephone survey in Iran.Methods: This study was part of a larger research in which adult citizens' self-perceived oral health was compared with an objective dental examination. The last-birthday method randomly selected a household member for each attempted landline number, asking the primary respondent to select an eligible family member with the most recent birthday. The selected respondent was then either contacted or replaced with another respondent from the same household based on the research criteria.Results: Of the ۶۷۴۵ called numbers, ۱۷۷۱ were invalid, ۳۱۲۹ did not respond, ۳۶۴ were not households, and ۷۷۱ declined to be interviewed. Finally, ۷۱۰ respondents entered the random selection procedure, of which ۵۳ had no eligible family member to select. The sample selection method's difficulty caused ۳۶ refusals. Of the ۶۲۱ selected final respondents, ۳۰ could not be contacted or refused upon introduction. The total percentage of "selection" and "post-selection” dropouts that could be attributed to the sample selection method was ۷.۴۱%. Based on the American Association for Public Opinion Research (AAPOR Response Rate ۱) guidelines, the minimum response rate for the interview was ۱۳%, and the AAPOR Response Rate ۳ was ۳۹.۶%. In all characteristics except for employment status (P = ۰.۴۸۸), the final participant's demographic characteristics were significantly different from those of the city population (P < ۰.۰۰۰۱).Conclusion: Oral health science can make use of the last-birthday selection strategy. This technique seems to obtain a reasonably representative sample through a respondent-friendly selection process in telephone surveys.

Iran, last-birthday, Oral Health, Population, Telephone interview