Introduction to Quality Control

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10 months ago

What is Quality?

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This means that a product should meet its specifications.

Refers to the measure that must be included during each assay run to verify that the test is working properly, according to pre-established specifications.
The definition of quality control is meeting the customer’s requirement for products or services.
Quality control in the laboratory is a statistical process used to monitor and evaluate the analytic process that produces patient results.

Need of Quality control in the laboratory:

Estabilizing written policies and procedures, including corrective actions
Training all laboratory staff
Ensuring complete documentation
Obtain control material
Collect Q.C. data
Reviewing quality control data
Set target values
Establish LJ chart
Preventive/assessment/corrective action
The primary goal of Q.C. is to identify and correct defects, errors or deviations from the desired quality level
It involves the systemic approach to inspecting, testing, and evaluating products or series at various stages of production or delivery

Internal quality control is a set of procedures for continuously assessing laboratory work and emergent results.
It is primarily a check of precision.
Internal quality control is necessary for the daily monitoring of the precision and accuracy of the analytical methods
Done daily in the lab
Applied to all work processes and every test done in the lab
Internal quality control procedures identify problems immediately.

It includes:

Control charts with tests on control materials
Duplicate tests on all specimens or a proportion of the specimens
Delta check, comparing current test results with previous results
Consistency of mean values of patient data;
Correlation check (e.g., blood film features or sensibility of interrelated parameters)

In Internal quality control we have to focus on two things:

Accuracy is how much test results are close towards the original values (actual values)
It is the closeness of the estimated value to the true mean.
It can be checked by the use of reference materials that have been assayed by independent methods of known precision.

2. Precision:

Precision is how much test result is close to each other when repeating some test several times.
It is the closeness of repeated measures to each other.

Precision = Repeatability or reproducibility.

Accuracy = Trueness + Precision.

2. External Quality Control:

It consists of unknown samples of whole blood or lyophilized serum/plasma representing the values that would be expected in a patient’s sample.
Samples were sent to the laboratory and tested with the normal sample batch with no special treatment.
Results are sent to the sample provider for statistical analysis.
The survey provider determines the target value for each test result through comparison studies with peer laboratories and establishes the acceptable performance ranges.
E.Q.C. is important for maintaining the long-term accuracy of the analytical methods.
E.Q.C. in the laboratory refers to the process of assessing and monitoring the accuracy and reliability of laboratory test results by an external entity.
It involves the participation of the laboratory in proficiency testing or external quality assessment programs, which are conducted by external organizations or regulatory bodies.
By participating in External Quality programmes, the laboratory can assess their proficiency, identify areas for implementation and maintain or enhance the quality of their tests.