Midterm Quality Control Flashcards
The overall activities conducted by the institution that are directed toward assuring the quality of the services provided
Quality assurance
Systematic action necessary to provide adequate confidence that laboratory services will satisfy given medical needs for patient care
Quality control
Focus on monitoring of outcomes or indicators of care
Quality assurance
Applies to the activities directed toward the monitoring of the individual elements of care
Quality control
Important for the daily monitoring of accuracy and precision of analytical methods.
IntraLab Internal Qc
Detects both random and systematic error
IntraLab internal Qc
It involves proficiency testing programs that periodically provide samples of unknown concentration of analytes to participating laboratories
Internal external Qc
Used to determine estimates of the state of the art interlab performance
Interlab external lab
Objective of quality control
Check stability of the machine
Quality of reagents
Technical errors
Result of improper product manufacturing, use of unpurified human and non human analyte additives and altered protein components
Matrix
Calculated from the mean and standard deviation
Control limits
To establish statistical quality control on a new instrument the diff levels of control material must be analyzed between?
5 and 20 days
Present in all measurement due to chance
Random error
Basis for varying differences between repeated measurement
Random error
Due to instrument operator and environmental condition
Random error
Example of random errors
Pipetting error
Mislabeling of sample
Temperature fluctuation
Improper mixing of sample and reagent
Error that influences observation consistently in one direction
Systematic error
Detected as either positive or negative bias
Systematic error
Is often related to calibration problems , deterioration of reagents and control materials, unstable and inadequate reagent blanks , contaminated solutions, failing instrumentation and poorly written procedures
Systematic error
Refers to a difference between the target value and the assay value. Independent of sample concentration
Constant error
Exists when there is a constant difference between comparative method and the test method regardless of the concentration
Constant error
Results from greater deviation from the target value due to higher sample concentration
Proportional / slope / percent error
Exists when the difference between the test method and the comparative method values are proportional to the analyte concentration
Proportional / slope / percent error
The highest frequency of clerical errors occurs with the use of handwritten labels and request forms
Clerical error
The first step in method evaluation
Precision study
Expressed either in measurement units of analyte or percentages
Allowable error
Pre analytical errors
Improper patient preparation Mislabeled specimen Incorrect order of draw Incorrect PC ID Wrong specimen container Incorrect anticoagulant to blood ratio Improper mixing of sample and reagent Incorrect specimen preservation Incorrect use of tubes Mishandled specimen
Post analytical error
Unavailable and delayed lab results
Incomplete lab results
Wrong transcription of the PC data and lab results
The science of gathering, analyzing, interpreting and presenting data
Statistic
A measurement of central tendency
Mean
A measurement of dispersion of values from the mean. Helps describe the normal curve. A measurement of distribution range
Standard deviation
Percentile expression of the mean. An index of precision
Coefficient of variation
Standards deviation squared
Variance
Largest value minus the smallest value in the data
Range
Midpoint of a distribution
Median
Most frequent observation
Mode
Use to compare the means of standard deviation of 2 groups of data
Inferential statistics
Used to determine whether there is a statistically significant difference between SD of two groups of data
T test
Used to determine difference between SD of 2 groups of data
F test
The difference between the value of a data point and the mean value divided by the groups SD
Standard deviation index
Referred as reference ranges
Reference interval
A pair of medical decision points that span the limits of results expected for a given condition
Reference interval
Value for an analyte that represents the boundary between different therapeutic Approach
Medical decision level
Range results between medical decision levels that corresponds to +- 2 of results from a healthy patient
Normal range
Reference interval applied to a therapeutic drug
Therapeutic range
Range of values that include a specific probability, usually 90% or 95%
Confidence interval
Different between the observed man and the reference mean
Bias
Tests values that tend to be lower or higher than the reference value
Neg and pos bias
