QUALITY CONTROL

QUALITY CONTROL IN BIOCHEMISTRY LAB: 

QUALITY CONTROL IN BIOCHEMISTRY LAB BY DR BRIJESH MUKHERJEE

TOTAL QUALITY MANAGEMENT: 

TOTAL QUALITY MANAGEMENT Total Quality Management (TQM) is an approach that seeks to improve quality and performance which will meet or exceed customer expectations .

TOTAL QUALITY MANAGEMENT: 

TOTAL QUALITY MANAGEMENT

QUALITY ASSURANCE VS QUALITY CONTROL: 

QUALITY ASSURANCE VS QUALITY CONTROL Quality assurance is used to represent practices that are generally recommended for ensuring that desired goals are achieved QA is broad spectrum of plans, policies and procedures that together form the parameters to achieve quality goals Quality control is a term used to represent those techniques and procedures that monitor performance parameter

ELEMENTS OF QUALITY ASSURANCE PROGRAM: 

ELEMENTS OF QUALITY ASSURANCE PROGRAM COMMITMENT FACILITIES AND RESOURCES - adequate space, equipment, materials, staffing, supervision and budgetary allocation TECHNICAL COMPETENCE - high quality personnel are essential for high quality services TECHNICAL PROCEDURE- Control of pre analytical errors Control of analytical variables Monitoring of analytical quality by the use of statistical methods and control charts

PowerPoint Presentation: 

The Quality Assurance Cycle Pre-Analytic Analytic Post-Analytic Data and Lab Management Safety Customer Service Patient/Client Prep Sample Collection Sample Receipt and Accessioning Sample Transport Quality Control Record Keeping Reporting Personnel Competency Test Evaluations Testing

What is Quality Control?: 

What is Quality Control? Process or system for monitoring the quality of laboratory testing, and the accuracy and precision of results Routinely collect and analyze data from every test run or procedure Allows for immediate corrective action

Quality systems : 

Quality systems Objectives To prevent risks To detect deviations To correct errors To improve efficiency To reduce costs How : By establishing a quality manual defining Organizational structure – Staff Responsibilities Procedures and processes Resources Documentation

The 5M’s of Quality: 

The 5M’s of Quality Man Material Machinery Manuals/Methodology ( SOP) Motivation

Designing a QC Program – : 

Designing a QC Program – Establish written policies and procedures Corrective action procedures Train all staff Design forms Assure complete documentation and review

Factors influencing quality:: 

Factors influencing quality: Pre analytical Analytical Post analytical Right specimen Laboratory professionals Recording Right collection Reagents Interpretation Right labeling Equipment Turnaround time Right quantity Selection of test - SOP Report to right user Right transport Records Right storage Bio-Safety

Components of Quality control : 

Components of Quality control Internal Quality control: IQC Nature: Concurrent performed by: lab staff Objective: Reliable results on a daily basis External quality assessment: EQA Nature: Retrospective to evaluate IQC Performed by: Independent agency Objective: Ensure inter laboratory comparability

Internal quality control (QC) programme may be formulated considering the following points:: 

Internal quality control (QC) programme may be formulated considering the following points: 1. Clinical correlation of test with the disease the patient is suspected to be suffering from. 2. Within-assay variation: The same sample is analyzed twice during an assay and the outcome noted. Results should be identical if no error exists; a large variation suggesting one or more errors. 3. Intra-laboratory duplicates: Samples may be analyzed in duplicates for 2 days and reproducibility of the four values checked. 4. The results of a test may be compared with the results of the same tests previously conducted on the patient. The values are expected to increase with disease progression and vice versa. A deviation from this pattern indicates error

External QC programme:: 

External QC programme : The concerned laboratory is provided with vials of controls without reference values for analysis under the conditions of that lab. The results obtained would be sent to the reference laboratory for verification. Internal QC programme is suitable to determine the reproducibility of result (precision). External QC programme is useful to assess the closeness of a result to the actual value (accuracy). If the result of the presently used method widely deviates from the majority of the other methods which agree with one another, the method should be immediately replaced by another. Revaluation of calibration standards, reagents, pipettes and measuring devices must be considered in case of any kind of deterioration

Qualitative vs. Quantitative: 

Qualitative vs . Quantitative Quantitative test measures the amount of a substance present Qualitative test determines whether the substance being tested for is present or absent

Qualitative QC: 

Qualitative QC Quality control is performed for both, system is somewhat different Controls available Blood Bank/Serology/Micro RPR/TPHA Dipstick technology Pregnancy

Implementing a QC Program –Quantitative Tests: 

Implementing a QC Program –Quantitative Tests Select high quality controls Collect at least 20 control values over a period of 20-30 days for each level of control Perform statistical analysis Develop Levey -Jennings chart Monitor control values using the Levey -Jennings chart and/or Westgard rules Take immediate corrective action, if needed Record actions taken

Selecting Control Materials Calibrators: 

Selecting Control Materials Calibrators Has a known concentration of the substance (analyte) being measured Used to adjust instrument, kit, test system in order to standardize the assay Sometimes called a standard, although usually not a true standard This is not a control

Selecting Control Materials Controls: 

Selecting Control Materials Controls Known concentration of the analyte Use 2 or three levels of controls Include with patient samples when performing a test Used to validate reliability of the test system

Control Materials Important Characteristics: 

Control Materials Important Characteristics Values cover medical decision points Similar to the test specimen (matrix) Available in large quantity Stored in small aliquots Ideally, should last for at least 1 year Often use biological material, consider bio-hazardous

Managing Control Materials: 

Managing Control Materials Sufficient material from same lot number or serum pool for one year’s testing May be frozen, freeze-dried, or chemically preserved Requires very accurate reconstitution if this step is necessary Always store as recommended by manufacturer

Sources of QC Samples: 

Sources of QC Samples Appropriate diagnostic sample Obtained from: Another laboratory EQA provider Commercial product

Types of Control Materials: 

Types of Control Materials Assayed mean calculated by the manufacturer must verify in the laboratory Unassayed less expensive must perform data analysis “Homemade” or “In-house” pooled sera collected in the laboratory characterized preserved in small quantities for daily use

How to carry out this analysis?: 

How to carry out this analysis? Need tools for data management and analysis Basic statistics skills Manual methods Graph paper Calculator Computer helpful Spreadsheet Important skills for laboratory personnel

Analysis of Control Materials: 

Analysis of Control Materials Need data set of at least 20 points, obtained over a 30 day period Calculate mean, standard deviation, coefficient of variation; determine target ranges Develop Levey -Jennings charts, plot results

Establishing Control Ranges: 

Establishing Control Ranges Select appropriate controls Assay them repeatedly over time at least 20 data points Make sure any procedural variation is represented: different operators different times of day Determine the degree of variability in the data to establish acceptable range

Measurement of Variability: 

Measurement of Variability A certain amount of variability will naturally occur when a control is tested repeatedly. Variability is affected by operator technique, environmental conditions, and the performance characteristics of the assay method. The goal is to differentiate between variability due to chance from that due to error.

Measures of Central Tendency: 

Measures of Central Tendency Median = the value at the center (midpoint) of the observations Mode = the value which occurs with the greatest frequency Mean = the calculated average of the values

Calculation of Mean: 

Calculation of Mean X = Mean X 1 = First result X 2 = Second result X n = Last result in series n – Total number of results

Calculation of Mean: 

Calculation of Mean 192 mg/ dL 194 mg/ dL 196 mg/ dL 196 mg/ dL 196 mg/ dL 200 mg/ dL 200 mg/ dL 202 mg/ dL 204 mg/ dL 208 mg/ dL 212 mg/ dL Sum = 2,200 mg/ dL Mean = the calculated average of the values The sum of the values (X 1 + X 2 + X 3 … X 11 ) divided by the number (n) of observations The mean of these 11 observations is (2200  11) = 200 mg/ dL

Normal Distribution: 

Normal Distribution All values are symmetrically distributed around the mean Characteristic “bell-shaped” curve Assumed for all quality control statistics

Normal Distribution: 

Normal Distribution Frequency 4.7’ 4.8’ 4.9’ Mean 5.1’ 5.2’ 5.3’

Normal Distribution: 

Normal Distribution Mean

ACCURACY VS PRECISION SPECIFICITY VS SENSITIVITY: 

ACCURACY VS PRECISION SPECIFICITY VS SENSITIVITY Accuracy has to do with how close the mean of a sufficiently large number of determinations on a sample is to the actual amount of substance present and is dependent on the methodology used. Precision refers to the extent to which repeated determination on an individual specimen vary using a particular technique and is dependent on how rigorously the methodology is followed. Specificity is the ability of an analytical method to determine solely the analyte it is required to measure. Sensitivity is the ability of an analytical method to detect small quantities of the measured analyte.

Accuracy and Precision: 

Accuracy and Precision The degree of fluctuation in the measurements is indicative of the “precision” of the assay. The closeness of measurements to the true value is indicative of the “accuracy” of the assay. Quality Control is used to monitor both the precision and the accuracy of the assay in order to provide reliable results .

Precision and Accuracy: 

Precise and inaccurate Precise and accurate Precision and Accuracy

Imprecise and inaccurate: 

Imprecise and inaccurate

Measures of Dispersion or Variability: 

Measures of Dispersion or Variability There are several terms that describe the dispersion or variability of the data around the mean: Range Variance Standard Deviation Coefficient of Variation

Range: 

Range Range refers to the difference or spread between the highest and lowest observations. It is the simplest measure of dispersion. It makes no assumption about the shape of the distribution or the central tendency of the data.

Calculation of Variance (S2): 

Calculation of Variance (S 2 )

Calculation of Variance: 

Calculation of Variance Variance is a measure of variability about the mean. It is calculated as the average squared deviation from the mean. the sum of the deviations from the mean, squared, divided by the number of observations (corrected for degrees of freedom)

Degrees of Freedom: 

Degrees of Freedom Represents the number of independent data points that are contained in a data set. The mean is calculated first, so the variance calculation has lost one degree of freedom (n-1)

Calculation of Standard Deviation : 

Calculation of Standard Deviation

Calculation of Standard Deviation: 

Calculation of Standard Deviation The standard deviation (SD) is the square root of the variance it is the square root of the average squared deviation from the mean SD is commonly used (rather than the variance) since it has the same units as the mean and the original observations SD is the principle calculation used in the laboratory to measure dispersion of a group of values around a mean

CALCULATE SD: 

CALCULATE SD CONSIDER 8 VALUES MEAN OF THE VALUES IS TO COMPUTE STANDARD DEVIATION

Standard Deviation and Probability: 

Standard Deviation and Probability For a set of data with a normal distribution, a value will fall within a range of: +/- 1 SD 68.2% of the time +/- 2 SD 95.5% of the time +/- 3 SD 99.7% of the time 68.2% 95.5% 99.7% Frequency -3s - 2s -1s Mean +1s +2s +3s

Standard Deviation and Probability: 

Standard Deviation and Probability In general, laboratories use the +/- 2 SD criteria for the limits of the acceptable range for a test When the QC measurement falls within that range, there is 95.5% confidence that the measurement is correct Only 4.5% of the time will a value fall outside of that range due to chance; more likely it will be due to error

Calculation of Coefficient of Variation: 

Calculation of Coefficient of Variation The coefficient of variation ( CV ) is the standard deviation ( SD ) expressed as a percentage of the mean Ideally should be less than 5%

Monitoring QC Data: 

Monitoring QC Data Use Levey -Jennings chart Plot control values each run, make decision regarding acceptability of run Monitor over time to evaluate the precision and accuracy of repeated measurements Review charts at defined intervals, take necessary action, and document

Levey–Jennings chart : 

Levey –Jennings chart Levey -Jennings chart is a graph that quality control data is plotted on to give a visual indication whether a laboratory test is working well. The distance from the mean is measured in standard deviations (SD). It is named after S. Levey and E. R. Jennings who in 1950 suggested the use of Shewhart's individuals control chart in the clinical laboratory.

Levey-Jennings Chart: 

Levey -Jennings Chart A graphical method for displaying control results and evaluating whether a procedure is in-control or out-of-control Control values are plotted versus time Lines are drawn from point to point to accent any trends, shifts, or random excursions

Levey-Jennings Chart: 

Levey -Jennings Chart

Levey-Jennings Chart - Record Time on X-Axis and the Control Values on Y-Axis: 

Levey -Jennings Chart - Record Time on X-Axis and the Control Values on Y-Axis Time (e.g. day, date, run number)

Levey-Jennings Chart - Plot Control Values for Each Run: 

Levey -Jennings Chart - Plot Control Values for Each Run Time (e.g. day, date, run number)

Levey-Jennings Chart Calculate the Mean and Standard Deviation; Record the Mean and +/- 1,2 and 3 SD Control Limits: 

Levey -Jennings Chart Calculate the Mean and Standard Deviation; Record the Mean and +/- 1,2 and 3 SD Control Limits Mean Day + 1SD +2SD +3SD -1SD -2SD -3SD

Levey-Jennings Chart - Record and Evaluate the Control Values: 

Levey -Jennings Chart - Record and Evaluate the Control Values Mean Day +1SD +2SD +3SD -1SD -2SD -3SD

Findings Over Time: 

Findings Over Time Ideally should have control values clustered about the mean (+/-2 SD) with little variation in the upward or downward direction Imprecision = large amount of scatter about the mean. Usually caused by errors in technique Inaccuracy = may see as a trend or a shift, usually caused by change in the testing process Random error = no pattern. Usually poor technique, malfunctioning equipment

Statistical Quality Control Exercise: 

Statistical Quality Control Exercise Hypothetical control values (2 levels of control) Calculation of mean Calculation of standard deviation Creation of a Levey -Jennings chart

When does the Control Value Indicate a Problem?: 

When does the Control Value Indicate a Problem? Consider using Westgard Control Rules Uses premise that 95.5% of control values should fall within ±2SD Commonly applied when two levels of control are used Use in a sequential fashion

PowerPoint Presentation: 

JAMES WESTGARD FOUNDER

Westgard Rules: 

Westgard Rules “ Multirule Quality Control” Uses a combination of decision criteria or control rules Allows determination of whether an analytical run is “in-control” or “out-of-control”

Westgard Rules (Generally used where 2 levels of control material are analyzed per run) : 

Westgard Rules ( Generally used where 2 levels of control material are analyzed per run) 1 2S rule 1 3S rule 2 2S rule R 4S rule 4 1S rule 10 X rule

Westgard – 12S Rule: 

Westgard – 1 2S Rule “warning rule” One of two control results falls outside ±2SD Alerts tech to possible problems Not cause for rejecting a run Must then evaluate the 1 3S rule

12S Rule = A warning to trigger careful inspection of the control data: 

1 2S Rule = A warning to trigger careful inspection of the control data Mean Day +1SD +2SD +3SD -1SD -2SD -3SD 1 2S rule violation

Westgard – 13S Rule: 

Westgard – 1 3S Rule If either of the two control results falls outside of ±3SD, rule is violated Run must be rejected If 1 3S not violated, check 2 2S

13S Rule = Reject the run when a single control measurement exceeds the +3SD or -3SD control limit: 

1 3S Rule = Reject the run when a single control measurement exceeds the +3SD or -3SD control limit Mean Day +1SD +2SD +3SD -1SD -2SD -3SD 1 3S rule violation

Westgard – 22S Rule: 

Westgard – 2 2S Rule 2 consecutive control values for the same level fall outside of ±2SD in the same direction, or Both controls in the same run exceed ±2SD Patient results cannot be reported Requires corrective action

22S Rule = Reject the run when 2 consecutive control measurements exceed the same +2SD or -2SD control limit: 

2 2S Rule = Reject the run when 2 consecutive control measurements exceed the same +2SD or -2SD control limit Mean Day +1SD +2SD +3SD -1SD -2SD -3SD 2 2S rule violation

Westgard – 41S Rule: 

Westgard – 4 1S Rule Requires control data from previous runs Four consecutive QC results for one level of control are outside ±1SD, or Both levels of control have consecutive results that are outside ±1SD

R4S Rule = Reject the run when 1 control measurement exceed the +2SD and the other exceeds the -2SD control limit: 

R 4S Rule = Reject the run when 1 control measurement exceed the +2SD and the other exceeds the -2SD control limit Mean Day +1SD +2SD +3SD -1SD -2SD -3SD R 4S rule violation

Westgard – 10X Rule: 

Westgard – 10 X Rule Requires control data from previous runs Ten consecutive QC results for one level of control are on one side of the mean, or Both levels of control have five consecutive results that are on the same side of the mean

10x Rule = Reject the run when 10 consecutive control measurements fall on one side of the mean: 

10 x Rule = Reject the run when 10 consecutive control measurements fall on one side of the mean Mean Day +1SD +2SD +3SD -1SD -2SD -3SD 10 x rule violation

Westgard Multirule QC: 

Westgard Multirule QC

When a rule is violated: 

When a rule is violated Warning rule = use other rules to inspect the control points Rejection rule = “out of control” Stop testing Identify and correct problem Repeat testing on patient samples and controls Do not report patient results until problem is solved and controls indicate proper performance

Summary: How to implement a QC program?: 

Summary: How to implement a QC program? Establish written policies and procedures Assign responsibility for monitoring and reviewing Train staff Obtain control materials Collect data Set target values (mean, SD) Establish Levey -Jennings charts Routinely plot control data Establish and implement troubleshooting and corrective action protocols Establish and maintain system for documentation

Solving “out-of-control” problems: 

Solving “out-of-control” problems Policies and procedures for remedial action Troubleshooting Alternatives to run rejection

Summary: 

Summary Why QC program? Validates test accuracy and reliability

Summary: How to implement a QC program?: 

Summary: How to implement a QC program? Establish written policies and procedures Assign responsibility for monitoring and reviewing Train staff Obtain control materials Collect data Set target values (mean, SD) Establish Levey -Jennings charts Routinely plot control data Establish and implement troubleshooting and corrective action protocols Establish and maintain system for documentation

DOCUMENTATION: 

DOCUMENTATION Main objective to establish, monitor and record “Quality” for all aspects of Good Laboratory Practices and Quality Control”. Type of documents Standard operating procedures Protocols of tests, results Reports

“IF you have not documented it you have not done it” : 

“ IF you have not documented it you have not done it” Laboratory records Description and identification of sample received Description of method of testing Record of all data secured in the course of the test Record of test results and how they compare with standards of identity, strength and quality Record of all deviations and modification of test Record of standardization of reference standards Record of calibration of equipments

THANK YOU: 

THANK YOU