Table 2

Features of a decision limit and a reference interval (modified from Ceriotti and Henny, 20089)

Reference intervalsDecision limits
DefinitionThe interval between, and including, two reference limits, which are values derived from the distribution of the results obtained from a sample of the reference population.The best dividing lines between the diseased and the not diseased or between ‘those who need not be investigated further’ and ‘those who do’.
Conditions influencing them
  • Population

  • Age group

  • Gender

  • Clinical question

  • Patient category

Information gatheredWhether or not the patient is part of the reference populationWhether or not the patient is eligible for a certain procedure (‘treatment’)
Statistics95% central range of the distribution curve
  • None (consensus values)

  • ROC curves

  • Predictive values

Data numberTwo (lower and upper limits)One, without any CI
There can sometimes be >1, but according to the likelihood of various clinical situations or different clinical questions
  • ROC, receiver operating characteristic.