{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,10]],"date-time":"2026-03-10T07:35:26Z","timestamp":1773128126533,"version":"3.50.1"},"reference-count":30,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2025,8,2]],"date-time":"2025-08-02T00:00:00Z","timestamp":1754092800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2025,8,2]],"date-time":"2025-08-02T00:00:00Z","timestamp":1754092800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100000072","name":"National Institute of Dental and Craniofacial Research","doi-asserted-by":"publisher","award":["F31DE031969"],"award-info":[{"award-number":["F31DE031969"]}],"id":[{"id":"10.13039\/100000072","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000072","name":"National Institute of Dental and Craniofacial Research","doi-asserted-by":"publisher","award":["R03DE033133"],"award-info":[{"award-number":["R03DE033133"]}],"id":[{"id":"10.13039\/100000072","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000072","name":"National Institute of Dental and Craniofacial Research","doi-asserted-by":"publisher","award":["R35DE034352"],"award-info":[{"award-number":["R35DE034352"]}],"id":[{"id":"10.13039\/100000072","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100009633","name":"Eunice Kennedy Shriver National Institute of Child Health and Human Development","doi-asserted-by":"publisher","award":["R01HD086742"],"award-info":[{"award-number":["R01HD086742"]}],"id":[{"id":"10.13039\/100009633","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100009633","name":"Eunice Kennedy Shriver National Institute of Child Health and Human Development","doi-asserted-by":"publisher","award":["R21HD072326"],"award-info":[{"award-number":["R21HD072326"]}],"id":[{"id":"10.13039\/100009633","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["aap.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal of Periodontology"],"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Self\u2010reported data can extend the reach of oral health research, but \u201cDon't know\u201d responses may threaten validity. We explored characteristics of participants who responded \u201cDon't know\u201d to a periodontal health question across three distinct cohorts.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      We used data from three questionnaire\u2010based observational studies, namely, the Pregnancy Study Online (PRESTO) (\n                      <jats:italic>N<\/jats:italic>\n                      \u00a0=\u00a010,996), the Black Women's Health Study (BWHS) (\n                      <jats:italic>N<\/jats:italic>\n                      \u00a0=\u00a0479), and the National Health and Nutrition Examination Survey (NHANES) (\n                      <jats:italic>N<\/jats:italic>\n                      \u00a0=\u00a015,502), to evaluate responses to questionnaire items related to periodontal health (e.g., \u201cHas a dentist or dental hygienist ever told you that you have periodontitis or gum disease?\u201d). We compared sociodemographic and behavioral factors across each response category (\u201cYes,\u201d \u201cNo,\u201d \u201cDon't know\u201d). We used Monte Carlo simulation to create multiple datasets of 100,000 participants under different scenarios to calculate the percent change in observed effect estimates in analyses using the full cohort compared to analytic cohorts excluding \u201cDon't know\u201d respondents.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\u201cDon't know\u201d prevalences ranged from 1.6% to 4.1%. We observed differences between \u201cDon't know\u201d responders and those who answered \u201cYes\u201d or \u201cNo\u201d across all three cohorts. \u201cDon't know\u201d responders were more likely to have lower educational attainment, lower income, and reduced engagement with oral healthcare services. We observed substantial bias in complete\u2010case effect estimates in some simulated scenarios. Bias was larger when the underlying population prevalence of \u201cDon't know\u201d responses was higher.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\u201cDon't know\u201d responders had distinct patterns of sociodemographic characteristics and oral healthcare engagement. The degree of bias in complete\u2010case analysis was dependent on simulated factors.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Plain Language Summary<\/jats:title>\n                    <jats:p>Research about oral health often asks people to answer questions about their teeth and gums. Sometimes people respond that they \u201cDon't know\u201d the answer to these questions, which can make data challenging for researchers to analyze. In this study, we used three different data sources to look at whether there were particular characteristics that were more common among people who said they \u201cDon't know\u201d in response to a question about their gum health. \u201cDon't know\u201d responses were not very common in any of the three groups, ranging from 1.6% in a representative survey of people in the United States to 4.1% in a group of women in the United States and Canada trying to become pregnant. In all three groups, people who said \u201cDon't know\u201d had a lower household income, less education, and were less likely to have seen a dentist recently. We also used simulated datasets to evaluate when excluding people who responded \u201cDon't know\u201d would be expected to cause the most bias in analyses. The expected bias increased with the number of \u201cDon't know\u201d responses in the data.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/jper.11378","type":"journal-article","created":{"date-parts":[[2025,8,2]],"date-time":"2025-08-02T09:09:07Z","timestamp":1754125747000},"page":"149-163","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Multi\u2010cohort evaluation of \u201cDon't know\u201d responders to self\u2010report oral health questions: Implications for etiologic research"],"prefix":"10.1002","volume":"97","author":[{"given":"Julia C.","family":"Bond","sequence":"first","affiliation":[{"name":"Department of Community Health Sciences Boston University School of Public Health  Boston Massachusetts USA"},{"name":"Department of Health Policy &amp; Health Services Research Boston University Henry M. 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Goldman School of Dental Medicine  Boston Massachusetts USA"},{"name":"Department of Epidemiology Boston University School of Public Health  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lauren A.","family":"Wise","sequence":"additional","affiliation":[{"name":"Department of Epidemiology Boston University School of Public Health  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yvette C.","family":"Cozier","sequence":"additional","affiliation":[{"name":"Department of Epidemiology Boston University School of Public Health  Boston Massachusetts USA"},{"name":"Slone Epidemiology Center at Boston University  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Matthew P.","family":"Fox","sequence":"additional","affiliation":[{"name":"Department of Epidemiology Boston University School of Public Health  Boston Massachusetts USA"},{"name":"Department of Global Health Boston University School of Public Health  Boston Massachusetts USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Raul I.","family":"Garcia","sequence":"additional","affiliation":[{"name":"Department of Health Policy &amp; Health Services Research Boston University Henry M. 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