Reference intervals Flashcards
what’s meant by reference interval (RI)
- range
- limited by an upper & lower limit
- represent central 95% of values in non-diseased pop
Importance of RI to interpret patient samples
interpret results if w/in range to make decisions about patient health
factors that need to be specified new RI needs to be established
- list INTERFERENCEs & source of variability
- outline selection CRITERIA & questionnaire
- CONSENT form
- HEALTH assess
- EXCLUDE ppl w/ poor health
- Decide NO. of participants considering confidence limit
- PREPARE participants for collection
- COLLECT & HANDLE specimens
- ANALYSING specimens
- prepare DISTRIBUTION of data
- Identify possible ERRORS &/ OUTLIERS
- Analyse REFERENCE VALUES
- DOCUMENT procedure
what methods are there if data is non-parametrical to Gaussian
- Log10 for transformation
- Box-Cox method for conversinon
minimum no. of participanst in non-parametric approach
39
determining the reference interval w/ non-parametric method
- rank-based
- LRL: 2.5th percentile = 0.025(N+1)
- LRL: 7.5th percentile = 0.975(N+1)
- N= highest value as rank
determining the reference interval w parametric method
mean +/- 2SD
minimum no. of participantsto achieve 90% confidence limits on ontervals is
120
Compare subject- vs population- based reference intervals
Subject: RI based on subject’s analytes when healthy & diseased
Population: Studies from non-disease population = RI are broad
