Statistical Tools, Performance Verification. Presented by: Karen S. Ginsbury For: IFF February 2011. Tools.
Presented by: Karen S. Ginsbury
Statistics is a science pertaining to the collection, analysis, interpretation or explanation, and presentation of valuable / useful data where the decision regarding what is collected is made up front.
Process Validation uses statistics, sampling and testing to predict process variability / uncertainty
Statistics is a mathematical science pertaining to the collection, analysis, interpretation or explanation, and presentation of data
Statisticians improve the quality of data with the design of experiments and survey sampling
Statistics provides tools for prediction and forecasting using data and models
Confidence Level is the likelihood - expressed as a percentage - that the results of a test are real and repeatable, and not just random
The idea is based on the concept of the "normal distribution curve," which shows that variation in almost any data (such as the heights of all fourth-graders, or the amount of rainfall in January) tends to be clustered around an average value, with relatively few individual measurements at the extremes
A confidence level of 50% means there is a 50:50 chance that your result is WRONG
75% means that one in four results will be WRONG
In pharma industry we usually want a minimum confidence level of 95% and that helps in selecting a sampling plan
Probability, or chance, is a way of expressing knowledge or belief that an event will occur or has occurred
Statistics is a means of assessing or predicting probability
At the process validation stage of product development we have a lot of uncertainty and wish to increase the probability of success through process understanding
Protocol should address the sampling plan including sampling points, number of samples, and the frequency of sampling for each unit operation and attribute
The number of samples should be adequate to provide sufficient statistical confidence of quality both within a batch and between batches
The confidence level selected can be based on risk analysis as it relates to the particular attribute under examination
Sampling during this stage should be more extensive than is typical during routine production
Criteria that provide for a rational conclusion of whether the process consistently produces quality products. The criteria should include:A description of the statistical methods to be used in analyzing all collected data (e.g., statistical metrics defining both intra-batch and inter-batch variability)
Typically will include:
An ongoing program to collect and analyze product and process data that relate to product quality must be established (§ 211.180(e)
Data collected should include relevant process trends and quality of incoming materials or components, in-process material, and finished products
The data should be statistically trended and reviewed by trained personnel
The information collected should verify that the critical quality attributes are being controlled throughout the process
We recommend that a statistician or person with adequate training in statistical process control techniques develop the data collection plan and statistical methods and procedures used in measuring and evaluating process stability and process capability
Procedures should describe how trending and calculations are to be performed
Procedures should guard against overreaction to individual events as well as against failure to detect process drift
Production data should be collected to evaluate process stability and capability
The quality unit should review this information. If done properly, these efforts can identify variability in the process and/or product; this information can be used to alert the manufacturer that the process should be improved
Good process design and development should anticipate significant sources of variability and establish appropriate detection, control, and/or mitigation strategies, alert and action limits
However, a process is likely to encounter sources of variation that were not previously detected or to which the process was not previously exposed
Many tools and techniques, some statistical and others more qualitative, can be used to detect variation, characterize it, and determine the root cause
We recommend that the manufacturer use quantitative, statistical methods whenever feasible
We recommend that it scrutinize intra-batch as well as inter-batch variation as part of a comprehensive continued process verification program
We recommend continued monitoring and/or sampling at the level established during the process qualification stage until sufficient data is available to generate significant variability estimates
Sampling and/or monitoring should be adjusted to a statistically appropriate and representative level with process variability periodically assessed
Does running three batches of a product or three processes mean that that process is valid? …Does it mean the process is effective?
Can you explain why what you do provides assurance that the process will produce the same result each time it is run? …or that the process is under control?
What are the process variables? …the things that will cause the process outcome to vary.
Are these variables understood and adequately controlled?
Prepare a summary report for PQ
Report is basis for ongoing protocol
Risk assessment focuses on “uncertainty”from stages 1 and 2
How much do we know after we have completed the Performance Qualification lots?
Develop a rationalized continued process verification strategy
The extent of verification and the extent of documentation should be based on risk to product quality and patient safety, as well as the complexity and novelty of the manufacturing system
Goal: Improve and Optimize the Process
Continued monitoring and/or sampling at the level established during the process qualification stage until sufficient data is available to generate significant variability estimates.
Once the variability is known, sampling and/or monitoring should be adjusted to a statistically appropriate and representative level.
Process variability should be periodically assessed and sampling and/or monitoring adjusted accordingly.
Once established, equipment qualification status must be maintained through routine monitoring, maintenance, and calibration procedures and schedules (21 CFR part 211, subparts C and D).
The data should be assessed periodically to determine whether re-qualification should be performed and the extent of that re-qualification.
Analyze the data for CPPs for (representative) batches and tie in with data for CQAs
It is about converting data into knowledge
i.e. how do CPPs affect CQA’s (if at all)
Very basic statistics:
Standard Deviation =
Very basic statistics:
Specification vs Control
Upper Specification Limit (USL)
Lower Specification Limit (LSL)
Upper Control Limit (UCL)
Lower Control Limit (LCL)
Process capability compares the output of an in-control process to the specification limits by using capability indices. The comparison is made by forming the ratio of the spread between the process specifications (the specification "width") to the spread of the process values, as measured by 6 process standard deviation units (the process "width")
Process capability compares the output of an in-control process to the specification limits by using capability indices
The comparison is made by forming the ratio of the spread between the process specifications (the specification "width") to the spread of the process values, as measured by 6 process standard deviation units (the process "width")
Most capability indices estimates are valid only if the sample size used is 'large enough'. Large enough is generally thought to be about 50 independent data values
The idea is to push your process closer to the mean and to have the mean in the middle of the USL and LSL i.e.REDUCE VARIABILITY
Now it is worth speaking to a statistician
Select method upfront and include in protocol
We recommend continued monitoring and / or sampling at the level established during the process qualification stage until sufficient data is available to generate significant variability estimates
The Product Control Strategy should establish appropriate sampling levels and process validation should demonstrate that it works. How much sampling is going to be expected?
Will data from pilot runs be acceptable as constituting some of the process validation data and would that mean that in some cases, if adequate scientific evidence is available – less than three commercial batches might be acceptable or concurrently released batches ?
Do and only do what is necessary…
…to assure that the process is under control and will produce quality product each time.
…validation is not an event, but a continuous process