HSBTE DMLT IVth Semester. Quality Assurance (Analytical control, Internal and external quality assurance in clinical laboratories important terms; precision, accuracy, standard deviation as per national standards)

Analytical control under Quality Assurance clinical laboratory

Quality assurance (QA) in a clinical laboratory is a set of systematic and planned activities designed to ensure that the processes, procedures, and outcomes related to laboratory testing meet specified requirements. The primary goal of quality assurance is to maintain and improve the accuracy, reliability, and overall quality of laboratory results.

Analytical control focuses on the systematic monitoring and evaluation of the analytical processes and methods used for testing patient samples. The objective is to ensure the accuracy, precision, and reliability of test results, ultimately contributing to the overall quality of patient care. The following are analytical controls under Quality Assurance in clinical laboratories:

• 1. Method Validation: The analytical method undergoes a validation process before implementing it. This involves assessing and documenting its accuracy, precision, specificity, sensitivity, and linearity. The validation process ensures that the method is suitable for use and provides reliable results.

• 2. Calibration: Regular calibration of laboratory instruments is essential to maintain accuracy. Analytical control includes establishing and following a calibration schedule for all relevant equipment.

• 3. Quality Control (QC) Samples: Quality control sample is also known as control material. It is used to monitor the performance of analytical methods. These samples have known concentrations or characteristics. They are analyzed with patient samples to detect any deviations from expected results. This identifies and corrects problems in the analytical process.

• 4. Internal Quality Control (IQC): IQC involves the routine use of control charts and statistical techniques to monitor the precision and accuracy of analytical methods over time.

• 5. External Quality Assessment (EQA): Participating in external testing programs is a main component of analytical control. Laboratories receive blind samples from external organizations. The results of the blind sample are compared with those of other participating laboratories. EQA assesses the laboratory's performance against external standards.

• 6. Reference Materials: The use of certified reference materials provides a known standard for comparison. Laboratories use these materials to verify the accuracy of their analytical methods.

Internal and external quality assurance in clinical laboratories

Internal and external quality assurances are two main components of the quality management system in clinical laboratories. They are designed to monitor and enhance the accuracy and reliability of laboratory test results. They ensure the delivery of high-quality patient care.

• 1. Internal Quality Assurance (IQA): Internal Quality Assurance (IQA) refers to the set of activities and processes implemented within the clinical laboratory to monitor and control the quality of testing procedures and results. The primary focus of IQA is on continuous monitoring and improvement of laboratory processes. Key elements of IQA include:

  • Quality Control: Regular use of control samples with known properties to monitor the precision and accuracy of analytical methods. This involves running these control samples alongside patient samples during routine testing.

  • Control Charts: Control charts are statistical tools. They are used in IQA to visually represent the variation in control sample results. Deviations from established control limits trigger investigations and corrective actions.

  • Calibration and Maintenance: Regular calibration and maintenance of laboratory instruments and equipment ensure accuracy and reliability in measurement.

  • Training and Competency Assessment: Ongoing training and competency assessments for laboratory personnel to maintain and enhance their skills.

  • Internal audit: Periodic internal audits of laboratory processes, procedures, and documentation to identify areas for improvement. It ensures compliance with established standards.

• 2. External Quality Assurance (EQA): External Quality Assurance (EQA) is also known as External Quality Assessment (EQA) or Proficiency Testing (PT). It involves the participation of a laboratory in external programs provided by external organizations. EQA focuses on comparing the laboratory's performance with that of other laboratories and external standards. The following are the main components of EQA

  • Proficiency Testing (PT): Laboratories receive blind samples from an external provider. The results obtained by the laboratory are compared with the results from other participating laboratories.

  • Benchmarking: EQA allows laboratories to benchmark their performance against external standards. It helps to identify areas for improvement. It also ensures that the laboratory is providing accurate and reliable results.

  • External Audit/Certification: Some external quality assurance programs involve external audits or certifications from accrediting bodies or regulatory agencies. Compliance with these external standards demonstrates the laboratory's commitment to quality.

  • Identification of Issues: EQA identify issues within the laboratory that may not be apparent through internal monitoring alone.

Precision, accuracy, and standard deviation as per national standards

Precision: Precision is the ability of a measurement to be reproduced under the same conditions. Precision is expressed as the coefficient of variation (CV). The coefficient of variation is the standard deviation (SD) divided by the mean, multiplied by 100 to get a percentage. Lower CV values indicate higher precision.

Accuracy: Accuracy is the closeness of a measurement to its true value. In the clinical laboratory, accuracy is assessed by comparing the laboratory's test results to an established reference or true value. Accuracy is expressed as bias. Bias is the difference between the laboratory result and the reference or target value. Minimizing bias is crucial for ensuring that laboratory results are as close as possible to the true values.

Standard Deviation (SD): Standard deviation is a measure of the spread or variability of a set of values. It quantifies how much individual measurements deviate from the mean (average). In the clinical laboratory, standard deviation is often used to assess the precision of a measurement. A smaller standard deviation indicates less variability and higher precision. A larger standard deviation suggests greater variability.