QUALITY ASSURANCE IN THE CLINICAL CHEMISTRY LABORATORY

It involves the process of monitoring the characteristics of the analytical processes and detects analytical errors during testing, and ultimately prevent the reporting of inaccurate patient test results.

It is one component of the quality assurance system, and is part of the performance monitoring that occurs after a test has been established.

It is a system ensuring accuracy and precision in the laboratory by including quality control reagents in every series of measurements.

Quality Control Reagents:

It is the ability of an analytical method to measure the smallest concentration of the analyte of interest.

It is the ability of an analytical method to measure only the analyte of interest.

It is the nearness or closeness of the assayed value to the true or target value.

Accuracy is estimated using 3 types of studies:

determines how much of the analyte can be identified in the sample.

determines if specific compounds affect the laboratory tests like hemolysis, turbidity and icteric.

is used to assess presence of error (inaccuracy) in actual patient sample.

Precision is also known as

It is the ability of an analytical method to give repeated results on the same sample that agree with one another.

It is the degree by which a method is easily repeated.

It is the ability of an analytical method to maintain accuracy and precision over an extended period of time during which equipment, reagents and personnel may change.

It is the ability of the analytical method to detect the proportion of individuals with the disease.

More true (+) and Less False (-)

Screening tests require high sensitivity so that no case is missed.

It is the ability of analytical method to detect the proportion of individuals without the disease.

More True (-) and less False (+)

Confirmatory tests require high specificity to be certain of the diagnosis.

It involves the analyses of control samples together with the patient specimens.

It detects changes in performance between the present operation and the "stable" operation.

It involves proficiency testing programs that periodically provides samples of unknown concentrations to participating clinical laboratories.

It is also used to determine state-of-the-art interlaboratory performance.

The College of American Pathologists (CAP) proficiency program is the gold standard for clinical laboratory external QC testing.

The ultimate goal of proficiency testing is to

General Chemistry:

Immunoassay:

New instrument

New lot numbers

Highly precise assays (with CV less than 1%) such as blood gases

are results of improper product manufacturing, use of unpurified human and nonhuman analyte additives and altered protein components.

It is recommended by Westgard et al and Clinical Laboratory Improvement Amendments (CLIA) that _________ samples be run by each method in duplicate on the same day over _________ , ideally within ______, to determine its accuracy and precision.

The first step in method evaluation is the _______ which estimates the random error.

It is determined for each test method and is expressed either in measurement units of the analyte

Are errors encountered in the collection, preparation and measurement of samples, including transcription and releasing of laboratory results.

It is present in all measurements; it is due to chance.

It is a type of error which varies from sample to sample.

It is the basis of varying differences between repeated measurements -variations in technique.

It is an error that influences observations consistently in one direction (constant difference).

It is a measure of the agreement between the measured quantity and the true value.

It is detected either positive or negative bias.

It refers to a difference between the target value and the assayed value.

It is independent of sample concentration.

It exists when there is a continual difference between the comparative method and the test method regardless of the concentration.

It results in greater deviation from the target value due to higher sample concentration.

It exists when the difference between the test method and the comparative method values is proportional to the analyte concentration.

highest frequency of clerical errors occurs with the use of

Nonlaboratory personnel were responsible for ____ of the errors with regard to laboratory results.

most error-free means of requesting laboratory tests.

Most laboratory errors occur in the

It is the science of gathering, analyzing, interpreting and presenting data.

are used to compare the means or standard deviations of two groups of data

is used to determine whether there is a statistically significant difference between the standard deviations of two groups of data

is the value of the observation that divides the observations into two groups, each containing equal number of observations. It is the midpoint of a distribution; 50th centile

is the most frequent observation; it is used to describe data with two centers (bimodal).

is the simplest expression of spread or distribution; it is the difference between the highest and lowest score in a data

is the difference between the value of a data point and the mean value divided by the group's SD

is used to determine whether there is a statistically significant difference between the means of two groups of data

Is a measure of central tendency. It is associated with symmetrical or normal distribution.

Is a measure of the dispersion of values from the mean. It helps describe the normal curve. A measure of the distribution range. It is the most frequently used measure of variation. describes the distribution of all values around the mean.

Is a percentile expression of the mean; an index of precision. allows a laboratorian to compare SDs with different units.

Is called the standard deviation squared; a measure of variability. It represents the difference between each value and the average of the data.

SD and variance represent the average distance from the center of the data (mean) and every value in the data set.

The acceptance range is ____ confidence limit which is equivalent to ±

It is used to observe values of control materials over time to determine reliability of the analytical method.

It is utilized to observe and detect analytic errors such as inaccuracy and imprecision.

It occurs when the data set can be accurately described by the SD and the mean.

It is obtained by plotting the values from multiple analyses of a sample.

It focuses on the distribution of errors from the analytical method rather than the values from a healthy or patient population.

It calculates the difference between QC results and the target means

Common method: V-mask

It identifies consistent bias problems; it requires computer implementation.

It is used to compare results obtained on a high and low control serum from the different laboratories.

The points falling from a center but on the 45˚ line suggest a

points falling from the center but not on the 45˚ line suggest a

It is the most widely used QC chart in the clinical laboratory.

It allows the laboratorians to apply multiple rules without the aid of a computer.

It is a graphic representation of the acceptable limits of variation in the results of an analytical method.

It easily identifies random and systematic errors.

It is formed by control values that either increase or decrease for six consecutive days.

Main cause of trend

It is formed by control values that distribute themselves on one side or either side of the mean for six consecutive days.

Main cause of shift

These are control values that are far from the main set of values

These are highly deviating values.

These are caused by random or systematic errors.

It recognizes that the use of simple upper and lower control limits is not enough to identify analytical problems.

Westgard used the term _______ to indicate if the analytical process is out of control.

A control value between 2s and 3s is a sign of a

A control value outside the 3s would require

Some laboratories use the ____ as a warning limit and the ____ as an error limit.

It is a performance improvement program.

It is a tool that can be used to reduce laboratory errors, increase productivity and improve quality in the clinical laboratory.

Main goal of six sigma

anything that does not meet customer requirements

It is a system for reducing waste ("non valued activities") especially in production or manufacturing processes.

It was conceptualized to improve the automobile industry in terms of the quality and efficiency of automobile production.

It is a set of control and patient specimens assayed, evaluated and reported together.

It is the most commonly used patient based-QC technique.

It requires computerization of test data so that current results can be compared with past results.

It is the difference between the two consecutive measurements of the same analytes on the same individual.

These are used to measure systematic errors or inaccuracy caused by substances other than the analyte.

Interferences: hemoglobin, lipids, bilirubin, anticoagulants and preservatives

It is the concentration range over which the measured concentration is equal to the actual concentration without modification of the method.

Is sometimes referred to as absurd value.

It helps detect sample concentration or dilution, inadequate sample volume, inadequate reagent volumes, sudden major problems with the method, or incorrect recording or transmission of the result.

It is a type of analytical testing performed outside the confines of the central laboratory, usually by non-laboratorian personnel (nurses, respiratory therapists, etc).

Most commonly used POCT: use of portable whole blood glucose meters for the management of patients with diabetes mellitus.

Primary Goal of QA:

It can be envisioned as a tripod with program development, assessment and monitoring, and quality improvement forming the three legs.

It includes effective test request forms, clear instruction for patient preparation and specimen handling, appropriate turn-around time for specimen processing, testing and result reporting, appropriate reference ranges and intelligent result reports.

It shows whether a method measures all the analytes or only part of it.

It estimates inaccuracy or systematic error.

It depends on sensitivity, specificity, and prevalence of the disease being test.

When a test cutoff changes, its accuracy (sensitivity/specificity) and predictive value also change.

Bayes' theorem (predictive value theory) describes the relationship between posttest and pretest probability of disease or no disease based on the sensitivity and specificity of the test.

It is the probability that a positive test indicates disease; it is the proportion of persons with a positive test who truly have the disease.

It is the probability that a negative test indicates absence of disease. It is the proportion of persons with a negative test who are truly without disease.

It is a value obtained by observation or measurement of a particular type of quantity on a reference individual.

It is the range of values into which 95% of non diseased individuals will fall - this definition implies that 5% of non diseased individuals can have laboratory results outside the reference range.

It is the usual values for a healthy population that represents 95% central tendency.