Robustness studies- Provide information to demonstrate that the product design is robust e.g.
insensitive to environmental and usage variation. Robustness (flex) studies are designed to challenge the system under conditions of stress to identify potential device deficiencies, including failures, and determine the robustness of the product. The manufacturer must consider multiple skill levels of users, as well as potential instrument and reagent problems. Below is a list of factors that may need to be considered when performing robustness studies: a) Operator error/ human factors, including not limited to; i. Use of incorrect specimen type, ii. Incorrect application of the specimen to the device (e.g., incorrect placement, incorrect volume), iii. Incorrect handling of reagents including those in self- contained unitized test devices, incorrect placement of device (e.g., non-level surface), iv. Incorrect placement of reagents, including strips, or other components that contain reagent, use of incorrect reagents (for example, reagents that are not specific for the particular device or lot or generic reagents), v. Incorrect order of reagent application, use of incorrect amount of reagent, incorrect timing of procedures (e.g., specimen application, running the test, or reading results), vi. Incorrect reading of test results, incorrect reading due to color blindness etc. b) Specimen integrity and handling including errors in specimen collection, use of inappropriate anticoagulant, clotted specimens, error in specimen handling, incorrect specimen transport and/or storage, presence of interfering substances, presence of bubbles in the specimen etc. c) Reagent integrity (Reagent viability) including use of improperly stored reagents, use of outdated reagents, use of improperly mixed reagents, use of contaminated reagents etc d) Hardware, software, and electronics integrity including power failure, power fluctuation, incorrect voltage, repeated plugging and unplugging of the device, hardware failure, software failure, electronic failure, physical trauma to unit etc. e) Stability of calibration and internal controls including factors that affect calibrator and calibration stability, factors that may interfere with calibration f) Environmental factors including impact of key environmental factors (heat, humidity, barometric pressure changes, altitude (if applicable), sunlight, surface angle, device movement, etc.) on reagents, specimens, and test results, impact of key environmental factors (including changes in parameters such as pH or temperature) etc. The following should be provided: i. A summary of the evidence that falls within this category, ii. State the test environment and relation to the intended use environment, iii. A discussion of what tests were considered for the device and why they were or were not performed, iv. A discussion to demonstrate why the evidence presented is sufficient to support the application, v. If a performance study has been conducted that includes human factors/usability end points, reference to the studies and endpoints should be made, but full results do not need to be repeated.