BACKGROUND: This study assessed the nature of potential biases by comparing respondents with non-respondents from a case-control study of breast cancer in younger women. METHODS: The case-control study was conducted in three regions in the US: Atlanta GA, Seattle/Puget Sound WA, and central New Jersey. An abbreviated interview or mailed questionnaire was completed by willing non-respondents, most of whom had refused participation in the main study. RESULTS: Respondents and non-respondents appeared similar with respect to age, race, relative weight, smoking, family history of breast cancer, number of births, age at first birth, and several dietary items. Compared to non-respondents, case and control respondents were of shorter stature, and reported less frequent consumption of doughnuts/pastries. Respondent cases, compared with non-respondent cases, were more highly educated and more likely to have consumed alcohol regularly; similar but not statistically significant tendencies were observed for controls. Respondent cases experienced menarche earlier than non-respondents. Respondent controls were more likely to have used oral contraceptives than non-respondents; a similar but not statistically significant tendency was observed in cases. Comparisons of crude and simulated relative risks using available non-respondents' data generally showed a low impact of non-response on relative risks in this study. CONCLUSIONS: Our results suggest that non-response would not greatly affect relative risk estimates in this study, except possibly regarding height. However, we were limited by the numbers of informative non-respondents and the amount of data collected. Collecting similar information in future studies would be useful, especially since varying methods used to encourage participation may lead to differences in respondents' characteristics.
BACKGROUND: This study assessed the nature of potential biases by comparing respondents with non-respondents from a case-control study of breast cancer in younger women. METHODS: The case-control study was conducted in three regions in the US: Atlanta GA, Seattle/Puget Sound WA, and central New Jersey. An abbreviated interview or mailed questionnaire was completed by willing non-respondents, most of whom had refused participation in the main study. RESULTS: Respondents and non-respondents appeared similar with respect to age, race, relative weight, smoking, family history of breast cancer, number of births, age at first birth, and several dietary items. Compared to non-respondents, case and control respondents were of shorter stature, and reported less frequent consumption of doughnuts/pastries. Respondent cases, compared with non-respondent cases, were more highly educated and more likely to have consumed alcohol regularly; similar but not statistically significant tendencies were observed for controls. Respondent cases experienced menarche earlier than non-respondents. Respondent controls were more likely to have used oral contraceptives than non-respondents; a similar but not statistically significant tendency was observed in cases. Comparisons of crude and simulated relative risks using available non-respondents' data generally showed a low impact of non-response on relative risks in this study. CONCLUSIONS: Our results suggest that non-response would not greatly affect relative risk estimates in this study, except possibly regarding height. However, we were limited by the numbers of informative non-respondents and the amount of data collected. Collecting similar information in future studies would be useful, especially since varying methods used to encourage participation may lead to differences in respondents' characteristics.
Authors: Andrew E Grulich; Claire M Vajdic; Michael O Falster; Eleanor Kane; Karin Ekstrom Smedby; Paige M Bracci; Silvia de Sanjose; Nikolaus Becker; Jenny Turner; Otoniel Martinez-Maza; Mads Melbye; Eric A Engels; Paolo Vineis; Adele Seniori Costantini; Elizabeth A Holly; John J Spinelli; Carlo La Vecchia; Tongzhang Zheng; Brian C H Chiu; Silvia Franceschi; Pierluigi Cocco; Marc Maynadié; Lenka Foretova; Anthony Staines; Paul Brennan; Scott Davis; Richard K Severson; James R Cerhan; Elizabeth C Breen; Brenda Birmann; Wendy Cozen Journal: Am J Epidemiol Date: 2010-08-18 Impact factor: 4.897
Authors: Kylie Ball; Anna Timperio; Jo Salmon; Billie Giles-Corti; Rebecca Roberts; David Crawford Journal: J Epidemiol Community Health Date: 2007-02 Impact factor: 3.710
Authors: Elisabeth F Beaber; Victoria L Holt; Kathleen E Malone; Peggy L Porter; Janet R Daling; Christopher I Li Journal: Cancer Epidemiol Biomarkers Prev Date: 2008-12 Impact factor: 4.254
Authors: Donghui Li; Rena Sue Day; Melissa L Bondy; Rashmi Sinha; Nga T Nguyen; Douglas B Evans; James L Abbruzzese; Manal M Hassan Journal: Cancer Epidemiol Biomarkers Prev Date: 2007-04 Impact factor: 4.254