Article on “Statistical Sampling Plans for Medical Devices”

One of the important aspects of design control of medical devices is statistical sampling plans for medical devices. To gain an understanding of the idea of statistical sampling plans for medical devices, one needs to understand the process of medical device design controls.

Statistical sampling plans for medical devices needs to be seen in this background: Under Sec. 820.30 of Title 21 of Code of Federal Regulations (CRF) the FDA sets out requirements from medical device manufacturers -which want to market certain categories of medical devices in the US -for establishing and maintaining procedures to implements design controls into the device.

An understanding of design controls is necessary first

First of all, what are design controls? Design controls are linearly and logically described and recommended steps that manufacturers have to take for ensuring that they have developed what they meant to develop. In addition, design controls have to also be implemented to ensure that the final product is in line with the expectations and needs from the customer's perspective.

Statistical sampling plans for medical devices come at a slightly later stage. Design controls pave way for the validation processes of design verification and design, which are done to ensure that the device design has met critical specifications or outputs and fulfill the requirements for the safety requirements, intended use, or specified application.

Verification and validation

This stage makes way for the next, which is fulfillment of design verification and validation (V&V), as required under Sec. 820.50 of 21 CFR. A core part of this code is the requirement from manufacturers for establishing and maintaining procedures to locate valid and proper statistical techniques for the process capability and product characteristics to be considered applicable. These are what constitute statistical sampling plans for medical devices

More of rule of thumb

Statistical sampling plans for medical devices need to be written and based on a well-established statistical foundation. However, the FDA does not prescribe a formal plan for writing down statistical sampling plans for medical devices. These are to be based more on rule of thumb. In other words, there are no acceptable limits violations under statistical sampling plans for medical devices. The statistical sampling plans for medical devices need to be implemented on a case-to-case basis, based on the device's characteristics and features.

In arriving at statistical sampling plans for medical devices, the FDA sets out the following rule:

Table 1

Binomial Staged Sampling Plans

Binomial Confidence Levels

able 2

Binomial Staged Sampling Plans

Binomial Confidence Levels

ucl = Upper Confidence Level

Source:http://www.fda.gov/ICECI/Inspections/InspectionGuides/ucm170830.htm

These constitute the core guidance for statistical sampling plans for medical devices.

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