This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Hannigan, A. Search for Related Content PubMed PubMed Citation Articles by Hannigan, A. Social Bookmarking                         What's this?

Using Survival Methodologies in Demonstrating Caries Efficacy

Department of Mathematics and Statistics, University of Limerick, Ireland; ailish.hannigan{at}ul.ie

ABSTRACT

Exploiting recent advances in statistical methods, particularly for correlated intra-subject data, could increase the efficiency of caries clinical trials. Methods of analysis using the tooth surface as the unit should be investigated. Whole-mouth measures such as the DMFS increment ignore the variation in the number of surfaces at risk between subjects and within a subject over time. The use of "survival time" for each surface as the outcome measure—i.e., the time from the start of the trial to when a surface is recorded as decayed or filled—is proposed. Data from caries clinical trials could be described as clustered survival data, where clustering of tooth surfaces exists such that survival times within the same cluster or subject are correlated. Advances in the analysis of clustered survival data, such as the use of marginal models with robust variance estimators, have recently been exploited in the analysis of caries clinical trials. The analysis produced results similar to those achieved by conventional DMFS-based analysis. The results using survival analysis are easily interpreted—for example, the median survival time of tooth surfaces in female subjects using a toothpaste with a higher level of fluoride (1500 ppm F) is 1.07 times the median survival time of surfaces in female subjects using toothpaste with less fluoride (1000 ppm F). Further research is required to investigate if survival analysis is a more sensitive method of analysis, i.e., whether causative factors can be identified with fewer subjects than with the conventional method of analysis.

Key Words: statistical analysis • multivariate survival data • efficiency

Journal of Dental Research, Vol. 83, No. suppl 1, C99-C102 (2004)
DOI: 10.1177/154405910408301S20


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				J.W. Stamm The Classic Caries Clinical Trial: Constraints and Opportunities Journal of Dental Research, July 1, 2004; 83(suppl_1): C6 - C14. [Full Text] [PDF]