MLS Quality Assurance & Standards 3 — Questions and Answers
Question 1: Which document type from CLSI provides consensus-based guidelines for laboratory procedures and standardization?
- OSHA standards
- EP documents (Correct answer)
- CAP checklists
- FDA guidance letters
Correct answer: EP documents
CLSI EP (Evaluation Protocol) documents provide standardized methods for evaluating analytical performance characteristics such as precision, accuracy, and interference.
Question 2: A laboratory notices a gradual upward trend in QC values over 10 days. The MOST likely cause is:
- Reagent degradation (Correct answer)
- Pipette contamination
- Random operator error
- Incorrect reference range
Correct answer: Reagent degradation
A gradual upward trend in QC values over time suggests progressive reagent deterioration, which introduces a systematic drift into the results.
Question 3: The term 'medical decision level' in QC refers to:
- The lowest detectable concentration of an analyte
- A clinically critical concentration used to place QC materials (Correct answer)
- The upper limit of the reference range
- The manufacturer's stated precision level
Correct answer: A clinically critical concentration used to place QC materials
Medical decision levels are clinically important concentrations (e.g., a glucose level indicating hypoglycemia) at which QC materials should ideally be targeted.
Question 4: Which accreditation organization uses the concept of 'deemed status' under CMS to accredit clinical laboratories?
- OSHA
- CAP (Correct answer)
- NIOSH
- AABB
Correct answer: CAP
The College of American Pathologists (CAP) has CMS-deemed status, meaning CAP-accredited laboratories are considered compliant with CLIA requirements.
Question 5: The analytical measurement range (AMR) of an assay defines:
- The reference interval for a healthy population
- The range over which the assay produces accurate results without dilution (Correct answer)
- The minimum detectable concentration of the analyte
- The acceptable QC variance limits
Correct answer: The range over which the assay produces accurate results without dilution
AMR is the range of analyte concentrations that the instrument can directly measure accurately without sample dilution or concentration.
Question 6: Which statistic is used to assess the agreement between two measurement methods in a Bland-Altman plot?
- Pearson correlation coefficient
- Limits of agreement (Correct answer)
- Coefficient of variation
- Regression slope
Correct answer: Limits of agreement
Bland-Altman plots display the mean difference (bias) and limits of agreement (±1.96 SD of differences) between two methods to assess clinical acceptability.
Question 7: A laboratory verifies a manufacturer's reference interval using 20 healthy individuals. If no more than how many values fall outside the interval is the range considered acceptable?
- 0
- 1
- 2 (Correct answer)
- 4
Correct answer: 2
CLSI EP28-A3c guidelines allow up to 2 of 20 (10%) reference interval values to fall outside the interval when verifying a manufacturer's claimed range.
MLS Quality Assurance & Standards 3
Which document type from CLSI provides consensus-based guidelines for laboratory procedures and standardization?