March 2020

Volume 37, Issue 1

Bias in population oral health research: longitudinal studies [Special issue of Community Dental Health, to be disseminated at ‘Random and Systematic Bias in Population Oral Health Research’ IADR symposium, March 2020, Washington DC.]

Authors: Roger Keller Celeste
doi: 10.1922/CDH_SpecialIssueCeleste06

Abstract

Abstract: Bias in longitudinal studies have been well described and the longer the follow-up, the higher the proportion of drop-outs. Here, I present some key issues related to selection bias, time-varying confounders, solutions to bias and challenges in longitudinal studies in dental research. Selection bias creates distortions in measures of disease frequency or association due to losses of follow-up or use of specific population groups. It is shown that even if losses are not associated with baseline values, measures such as odds ratios may be seriously distorted. Such problems can be understood by directed acyclic graphs, identifying the collider bias, or by missing data theory. Time-varying confounding occurs when an exposure varies over time and is affected by past exposure of other time-varying covariates, creating a complex scenario to adjustment in multiple regression. Under some assumptions, missing information may be informed by other variables in the dataset, and techniques such as multiple imputation or inverse probability weighting can be helpful, but the best solution is to prevent losses of follow-up as much as possible. Finally, I present challenges for longitudinal studies that use electronic health records and the need to incorporate area-based contextual measures. The first allows linkage of dental records with other information systems to create longitudinal (big) data. The second allows evaluation longitudinally of the effect of contextual factors, including social and health policies, on oral health. Keywords: epidemiology; oral health; dental public health, bias; longitudinal studies.

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Determinants of periodontitis among a rural Indian population: A case control study 26-31 Download
Effect of treating carious teeth on children’s and adolescents’ anthropometric outcomes: A systematic review of randomised controlled trials 32-38 Download
Perspectives of socially disadvantaged women on oral healthcare during pregnancy 39-44 Download
Assessing the conceptual model of the Oral Health Impact Profile-49 (OHIP-49): A path analysis 45-50 Download
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Proceedings of EADPH Pre-Congress Workshop held on Wednesday, 11 September 2019 at Het Pand, University of Ghent, Belgium 65-82 Download
Random and Systematic Bias in Population Oral Health Research: an introduction 83-83 Download
Estimating Bias Due to Unmeasured Confounding in Oral Health Epidemiology [Special issue of Community Dental Health, to be disseminated at ‘Random and Systematic Bias in Population Oral Health Research’ IADR symposium, March 2020, Washington DC.] 84-89 Download
Bias in population oral health research: longitudinal studies [Special issue of Community Dental Health, to be disseminated at ‘Random and Systematic Bias in Population Oral Health Research’ IADR symposium, March 2020, Washington DC.] 90-95 Download
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