Evaluating the validity of probing attachment loss as a surrogate for tooth mortality in a clinical trial on the elderly

J Dent Res. 1997 Apr;76(4):858-66. doi: 10.1177/00220345970760040701.

Abstract

Most periodontal trials are based on the assumption that the superior treatment, as judged by short-term intangible changes in probing attachment levels (the surrogate), is also the treatment most likely to affect tooth mortality. This assumption is valid if: (1) the surrogate is informative about tooth mortality, and (2) the surrogate captures a substantial proportion of the treatment effect on tooth mortality (e.g., > 50% or 75%). The goal of this study was to evaluate whether both conditions were satisfied in a randomized controlled trial (RCT) of elders at high risk for dental diseases. The results suggested that the first condition for a valid surrogate was satisfied: Both one- and two-year changes in probing attachment level were informative about tooth mortality risk. A 1-mm loss measured over a one-year period was associated with a 56% increased tooth mortality risk (relative risk = 1.56; 95% confidence interval, 1.08 to 2.26; p = 0.017); a 1-mm loss measured over a two-year period was associated with a 102% increased risk for tooth mortality (relative risk = 2.02; 95% confidence interval, 1.26 to 3.25; p = 0.004). The second condition necessary for a valid surrogate could not be confirmed in the present trial. With 95% confidence, it was concluded that one-year changes in probing attachment level measurements did not capture a significant proportion of the treatment effect (point estimate, 6%; 95% confidence interval;-38% to 53%). No useful statements could be made regarding the proportion of treatment effect captured by two-year changes, due to the width of the confidence interval (point estimate, 18%; 95% confidence interval;-151% to 140%). It is concluded that (1) the evidence surrounding the one-year change in probing attachment level indicates that it can be ruled out as being anything more than a weak surrogate marker for tooth mortality, and (2) further research is required to study the validity of two-year change in probing attachment level as a surrogate marker. Due to characteristics of the population and the treatments investigated, the generalizability of these findings to other RCTs is questionable.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Analysis of Variance
  • Anti-Infective Agents, Local / therapeutic use
  • Behavior Therapy
  • Chlorhexidine / therapeutic use
  • Clinical Trials as Topic / methods
  • Confidence Intervals
  • Dental Care for Aged / methods*
  • Dental Prophylaxis
  • Dental Research / methods
  • Fluorides, Topical / therapeutic use
  • Humans
  • Outcome Assessment, Health Care
  • Periodontal Attachment Loss / diagnosis*
  • Periodontal Attachment Loss / therapy*
  • Periodontal Pocket / diagnosis
  • Periodontics / instrumentation
  • Predictive Value of Tests
  • Prognosis
  • Regression Analysis
  • Reproducibility of Results
  • Risk Assessment
  • Tooth Loss / diagnosis*
  • Tooth Loss / prevention & control

Substances

  • Anti-Infective Agents, Local
  • Fluorides, Topical
  • Chlorhexidine