Reference intervals

Question 1

what’s meant by reference interval (RI)

Answer 1

• range
• limited by an upper & lower limit
• represent central 95% of values in non-diseased pop

Question 2

Importance of RI to interpret patient samples

Answer 2

interpret results if w/in range to make decisions about patient health

Question 3

factors that need to be specified new RI needs to be established

Answer 3

1. list INTERFERENCEs & source of variability
2. outline selection CRITERIA & questionnaire
3. CONSENT form
4. HEALTH assess
5. EXCLUDE ppl w/ poor health
6. Decide NO. of participants considering confidence limit
7. PREPARE participants for collection
8. COLLECT & HANDLE specimens
9. ANALYSING specimens
10. prepare DISTRIBUTION of data
11. Identify possible ERRORS &/ OUTLIERS
12. Analyse REFERENCE VALUES
13. DOCUMENT procedure

Question 4

what methods are there if data is non-parametrical to Gaussian

Answer 4

• Log10 for transformation

- Box-Cox method for conversinon

Question 5

minimum no. of participanst in non-parametric approach

Answer 5

39

Question 6

determining the reference interval w/ non-parametric method

Answer 6

• rank-based
• LRL: 2.5th percentile = 0.025(N+1)
• LRL: 7.5th percentile = 0.975(N+1)
• N= highest value as rank

Question 7

determining the reference interval w parametric method

Answer 7

mean +/- 2SD

Question 8

minimum no. of participantsto achieve 90% confidence limits on ontervals is

Answer 8

120

Question 9

Compare subject- vs population- based reference intervals

Answer 9

Subject: RI based on subject’s analytes when healthy & diseased
Population: Studies from non-disease population = RI are broad