This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted 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. Articles by Roberts, A.J. Search for Related Content PubMed PubMed Citation Articles by Hannigan, A. Articles by Roberts, A.J. Social Bookmarking                         What's this?

A Re-analysis of a Caries Clinical Trial by Survival Analysis

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

D.M. O'Mullane

Oral Health Services Research Centre, University College Cork, Ireland

D. Barry

'Department of Mathematics and Statistics, University of Limerick, Ireland

F. Schafer

Unilever Dental Research, Port Sunlight, UK

A.J. Roberts

Unilever Dental Research, Port Sunlight, UK

The decline in caries prevalence, the increases in the level of fluoride exposure, and the lack of placebo control subjects have complicated caries clinical trials in recent times. There has been a substantial increase in the numbers of subjects required for the detection of statistically significant differences between dental products, and hence, the cost of these trials has grown enormously. This study uses a new statistical approach to the analysis of the data from these trials with the ultimate aim of providing a more sensitive method of analysis. The new approach uses survival analysis, where the outcome measure is the survival time of an individual tooth surface. It exploits recent developments in the analysis of clustered survival data where survival times within the same cluster or subject are correlated. To illustrate, the new method of analysis was used for the North Wales, UK, caries clinical trial. It is concluded that survival analysis uses most of the data available in a caries clinical trial, an outcome measure that is easily understood and may lead to a more sensitive method of analysis.

Key Words: caries clinical trials • statistical • clustered survival data.

REFERENCES

• Beck JD, Lawrence HP, Koch GG ( 1997). Analytic approaches to longitudinal caries data in adults. Community Dent Oral Epidemiol 25:42-51.[CrossRef][Medline] [Order article via Infotrieve]
• Carlos JP, Gittelsohn AM (1965). Longitudinal studies of the natural history of caries. II. A life-table study of caries incidence in the permanent teeth. Arch Oral Biol 10:739-751.[CrossRef][Medline] [Order article via Infotrieve]
• Chesters RK, Huntington E., Burchell CK, Stephen KW (1992). Effect of oral care habits on caries in adolescents. Caries Res 26:299-304.[Medline] [Order article via Infotrieve]
• Collett D. (1994). Modelling survival data in medical research. London: Chapman and Hall.
• DeRouen TA, Hujoel PP, Mancl LA (1995). Statistical issues in periodontal research. J Dent Res 74:1731-1737.
• Hannigan A., O'Mullane DM, Barry D., Schafer F., Roberts AJ (2000). A caries susceptibility classification of tooth surfaces by survival time. Caries Res 34:103-108.[CrossRef][Medline] [Order article via Infotrieve]
• Hujoel PP, Loesche WJ, DeRouen TA (1990). Assessment of relationships between site-specific variables. J Periodontol 61:368-372.[Medline] [Order article via Infotrieve]
• Hujoel PP, Isokangas PJ, Tiekso J., Davis S., Lamont RJ, DeRouen TA, et al. (1994). A re-analysis of caries rates in a preventive trial using Poisson Regression Models. J Dent Res 73:573-579.
• Klein H., Palmer CE (1938). Studies on dental caries. VII. Sex differences in dental caries experience of elementary schoolchildren. Public Health Rep 53:1685.
• Lipsitz SR, Parzen M. (1996). A jackknife estimator of variance for Cox regression for correlated survival data. Biometrics 52:291-298.
• Lipsitz SR, Dear KB, Zhao L. ( 1994). Jackknife estimators of variance for parameter estimates from estimating equations with applications to clustered survival data. Biometrics 50:842-846.
• O'Mullane DM, Kavanagh D., Ellwood RP, Chesters RK, Schafer F., Huntington E., et al. (1997). A three-year clinical trial of a combination of trimetaphosphate and sodium fluoride in silica toothpastes. J Dent Res 76:1776-1781.
• Wei LJ, Lin DY, Weissfeld L. (1989). Regression analysis of multivariate incomplete failure time data by modeling marginal distributions. JAm Stat Assoc 84:1065-1073.

Journal of Dental Research, Vol. 80, No. 2, 427-431 (2001)
DOI: 10.1177/00220345010800020501


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]

				L.A. Mancl, P.P. Hujoel, and T.A. DeRouen Efficiency Issues Among Statistical Methods for Demonstrating Efficacy of Caries Prevention Journal of Dental Research, July 1, 2004; 83(suppl_1): C95 - C98. [Abstract] [Full Text] [PDF]

				A. Hannigan Using Survival Methodologies in Demonstrating Caries Efficacy Journal of Dental Research, July 1, 2004; 83(suppl_1): C99 - C102. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted 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. Articles by Roberts, A.J. Search for Related Content PubMed PubMed Citation Articles by Hannigan, A. Articles by Roberts, A.J. Social Bookmarking                         What's this?