A study of the reliability of a no disease progression conclusion

Concluding that the clinical attachment level at a periodontal site is stable, while in reality it is progressing at a clinically relevant rate, is an example of a false-negative conclusion. No guidelines are currently available to evaluate the likelihood for false-negative conclusions in periodontal clinical trials that monitor disease progression by means of clinical attachment levels. The goal of this study was to estimate the amount of linear disease progression in clinical attachment levels that cannot reliably be detected, when it is truly present. This rate is called the critical linear rate; rates equal to or below this critical linear rate cannot reliably be detected. An equation for determining the critical linear rates for various clinical situations is presented and may provide a rule-of-thumb guideline for the interpretation of negative conclusions. If the critical linear rate for a study is larger than what is considered a clinically relevant disease progression rate, negative conclusions should be interpreted with caution; clinically relevant disease progression might be present, but the diagnostic tools used were too insensitive to detect it. False-negative conclusions may be important in diagnostic trials where low sensitivity can translate into lack of clinical utility.