Sample Size for Biocompatibility Tests

#1
Hi all,

So far, i was of the opinion that a sample size of 1 is sufficient for biocompatibility tests (given that your device provides a reasonably large surface area).
However, my QA department now wants to have a sample size justification. I can't find anything in the ISO 10993 series. I do not know how i can argue that a sample size of 1 is sufficient.
Did anybody else encounter this issue? Any ideas on how to resolve this?
Thanks

Freddo
 
Elsmar Forum Sponsor

yodon

Leader
Super Moderator
#2
My experience has been that the test labs require a specific amount of surface area of the material. "Sample counts" are mostly irrelevant.
 

ScottK

Not out of the crisis
Leader
Super Moderator
#4
Yes, that is exactly what my understanding is. But is there any way to justify this?
present the recommendations of the lab that you intend to use as your justification.
I've done cytotoxicity and endotoxin studies with one sample each from three lots of the material in question for indirect contact materials.
 

Bev D

Heretical Statistician
Leader
Super Moderator
#5
The issue here is that "sample sizes" are calculated based the variability of the population. so the intent of the test, the science of the test, and thing under test and the inherent variability of the thing to the characteristic being tested all matter: sometimes this gives us a probabilistic situation and sometimes it gives us a deterministic situation. traditional sample size calculations are used in a probabilistic situation.

biocompatibility testing is to determine if the inherent design choices are acceptable or not. if you think your design choices will be variable you probably need a better design - or at least a more controlled set of material suppliers or manufacturing processes. If your design is appropriate then it isn't a matter of how many things you test, it's about the area of the specimen - is it large enough to provide an adequate opportunity? So your "sample size" is not the number of things but the area of the specimen of one thing...

If you suspect that there may be some manufacturing variability (contamination, coating thickness, whatever) then it's a matter of getting a single sample from multiple manufacturing events (3 being the minimum and usually sufficient number). But this really should be done during development or during verification when brining on a new supplier or manufacturing line...
 
Thread starter Similar threads Forum Replies Date
V Sample Size rationale to reduce size and use special levels EU Medical Device Regulations 6
Q Gage Pin Sets? Calibrate/Verify them all or just a sample size? General Measurement Device and Calibration Topics 22
S How to determine sample size to test when the acceptance criteria is x >= Standard value? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 7
T Sample size calculation Using Minitab Software 3
C What Theory is MIL-STD-105E Sample Size Code Letters Based on? Quality Tools, Improvement and Analysis 3
Y FMEA link to Control Plan frequency and sample size FMEA and Control Plans 19
T Noob question regarding sample size Inspection, Prints (Drawings), Testing, Sampling and Related Topics 4
S Help needed in choosing the method of calculating the minimum sample size Internal Auditing 12
D Estimate Sample Size for very rare event Using Minitab Software 1
S Determining Sample Size and Method Quality Tools, Improvement and Analysis 12
C Complaint Return Sample Size Question 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 4
shimonv Frequency and sample size for lot release of EtO sterilized products EU Medical Device Regulations 2
A Clinical assessment sample size - Medical device Class IIb implantable (93/42 directive) EU Medical Device Regulations 2
P Sample Size for Distribution Simulation Testing Inspection, Prints (Drawings), Testing, Sampling and Related Topics 11
C Stress / Challenge Conditions for Design Verification Testing to Reduce Sample Size 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 11
K How can Acceptance Number and Reject Number be larger than Sample Size on Z1.4 Table? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 8
J Validation Sample Size for Tray Seal Qualification and Validation (including 21 CFR Part 11) 4
D Design Verification Sample Size vs Repeats Statistical Analysis Tools, Techniques and SPC 9
M Minimum sample size - Guidance and statistical rationale Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
P Unrealistic Packaging Validation Sample Size 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 41
J Control chart for huge sample size Statistical Analysis Tools, Techniques and SPC 9
S Is there a standard for sample size during R&D phase Other ISO and International Standards and European Regulations 18
J Sample size definition in an Automotive SMT pilot lot run Misc. Quality Assurance and Business Systems Related Topics 1
E Correct way to certify hydrostatic testing when it is not 100% (and Sample Size) Various Other Specifications, Standards, and related Requirements 6
B Determining sample size for device sterility Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
D Determining of sample size for 'Operational Qualification' AQL - Acceptable Quality Level 5
F Bayes Success run Theorem for sample size during OQ&PQ Qualification and Validation (including 21 CFR Part 11) 4
I Device modifications - Clinical sample size rationale EU Medical Device Regulations 5
J Sample size for creating a data base as a reference to a tested variable Other Medical Device and Orthopedic Related Topics 6
T Sample Size for Design Validation Design and Development of Products and Processes 4
C AS9138 Sample Size Determination AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 1
V Acceptable maximum RSD (relative standard deviation) for an sample size Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
E Sample size for design verification of variable in single use device Design and Development of Products and Processes 20
R Sample size for clinical validation/investigation EU Medical Device Regulations 4
R Process Validation sample size selection Statistical Analysis Tools, Techniques and SPC 0
J Interesting Discussion Sample Size Determination for Medical Device Other Medical Device and Orthopedic Related Topics 19
P Is it possible to make an educated decision using a very very small sample size? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
V Firmware Verification Testing & Sample Size Software Quality Assurance 1
R Determining Sample Size for Medical Device Component Validation Inspection, Prints (Drawings), Testing, Sampling and Related Topics 0
S Surveillance Sampling Test - Determining Sample Size Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
H Sample Size Calculation (Confidence Interval and Reliability) - Medical Devices Reliability Analysis - Predictions, Testing and Standards 9
P Cleaning and Disinfection Validation Sample Size of 3? Other Medical Device Related Standards 2
V Sample Size Calculation for Image Analysis - Microscopy Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
G Sample Size, Significant Figures, Scale General Measurement Device and Calibration Topics 3
L Heated Sealed Packages - Sample Size for OQ (Operational Qualification) and PQ Inspection, Prints (Drawings), Testing, Sampling and Related Topics 11
P Frequency and Sample Size Requirements for an MSA Studies Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
V When and How to apply the Bayes Success Run approach for Sample Size Determination Inspection, Prints (Drawings), Testing, Sampling and Related Topics 4
N Sample Size Justification for Medical Device Shelf-Life Inspection, Prints (Drawings), Testing, Sampling and Related Topics 13
C Process Qualification Sample size Document Control Systems, Procedures, Forms and Templates 6
G Sample size for IEC 60601-1-11 environmental tests IEC 60601 - Medical Electrical Equipment Safety Standards Series 1

Similar threads

Top Bottom