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The WALLSTENT® Enteral Endoprosthesis with Unistep™ Delivery System is indicated for palliative treatment of colonic, duodenal or gastric outlet obstruction or strictures caused by malignant neoplasms, and to relieve large bowel obstruction prior to colectomy in patients with malignant strictures.

The WALLSTENT® Enteral Endoprosthesis with Unistep™ Delivery System is composed of two components: the implantable metallic stent and the delivery device. The stent is composed of implant-grade cobalt-base superalloy wire braided in a tubular mesh configuration. The design configuration results in a stent that is flexible, compliant, and self-expanding. The stent is available in multiple sizes. Physician preference and individual patient condition and/or anatomy will determine the appropriate size chosen.

Here's an analysis of the provided text regarding the acceptance criteria and study for the WALLSTENT® Enteral Endoprosthesis, formatted to include the requested information.

Note: The provided document is a 510(k) summary for a medical device seeking an additional indication for a device that is already legally marketed. This type of submission relies heavily on the equivalence to a predicate device and often does not involve a new, large-scale clinical study for the specific expanded indication if the technological characteristics are identical.

Wallstent® Enteral Endoprosthesis - Acceptance Criteria and Study Analysis

This 510(k) submission primarily focuses on demonstrating substantial equivalence to a predicate device for an additional indication (gastric outlet obstruction or strictures). The device itself (materials, construction, processing) is identical to the predicate. Therefore, the "study" demonstrating the device meets acceptance criteria largely relies on the prior performance of the predicate device and a literature review for the new indication.

1. Table of Acceptance Criteria and Reported Device Performance

• Corrosion resistance (biocompatibility and durability)
• Relative radial force (ability to effectively open and maintain lumen diameter)
• Stent deformation (resistance to collapse or shape change) | "Performance testing was done on predicate devices. Tests included fatigue, corrosion resistance, relative radial force, and stent deformation testing to assure mechanical strength of the wire. The results were all within the expected ranges."
  Note: These tests were not repeated for this submission as the device is identical to the predicate. |
  | Safety & Effectiveness | - Biocompatibility (no adverse biological reactions)
• Ability to palliate obstruction/strictures
• No new safety concerns compared to predicate | The device is "physically identical" to the predicate.
  "A search of clinical literature has found that the clinical in vivo experience of a stent within the clinical indication that we are requesting has been successful. In brief a metal stent placement within the obstructed colon permits definitive surgery to be postponed until it can be performed in a better prepared patient."
  "The results of the literature search and tests demonstrate that the WALLSTENT® Enteral Endoprosthesis with Unistep™ Delivery System is equivalent to the predicate device and is therefore safe and effective for its intended use." |
  | Technological Characteristics | - Materials
• Construction
• Processing | "The WALLSTENT® Enteral Endoprosthesis with Unistep™M Delivery System has technological (materials, construction, processing) characteristics identical to those of the predicate WALLSTENT® device." |

2. Sample Size Used for the Test Set and Data Provenance

• Test Set (for Mechanical/Performance Data): Not explicitly stated as a "sample size" in the context of a new human clinical study. The performance testing was done on predicate devices, implying a set of devices manufactured under the same specifications. The exact number of units tested for fatigue, corrosion, etc., is not provided, but it would have been a representative sample according to recognized test standards for medical devices.
• Data Provenance: The mechanical/performance data originated from testing of the predicate devices (likely in a laboratory setting, location not specified but presumably where the manufacturer's R&D/testing is conducted).
• Clinical Data (for New Indication): The clinical evidence for the additional indication relies on a literature search. This implies aggregated data from published clinical studies, not a specific "test set" commissioned by Boston Scientific for this 510(k). Therefore, the data provenance would be global, retrospective clinical study data from various published sources.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

• Mechanical/Performance Data: The "ground truth" for the mechanical tests would be established by engineering specifications and recognized test standards. The "experts" would be the engineers and quality assurance personnel conducting and interpreting these tests, qualified in mechanical engineering, materials science, and medical device testing. No specific number is provided, typical of in-house testing.
• Clinical Data (Literature Review): The "ground truth" for the clinical effectiveness in the new indication (gastric outlet obstruction) was established by the published outcomes of the studies included in the literature review. The "experts" here would be the authors and peer reviewers of those published clinical studies (likely interventional gastroenterologists, surgeons, radiologists, etc., with relevant experience). The submission itself does not indicate Boston Scientific used its own panel of experts to re-establish ground truth for the literature review; rather, they are relying on the established findings in the medical literature.

4. Adjudication Method for the Test Set

• Mechanical/Performance Data: Adjudication for mechanical tests typically involves adherence to pre-defined test protocols, acceptance criteria, and standard operating procedures. Any deviations or borderline results would be adjudicated by the engineering and quality teams, potentially with input from regulatory experts. No specific "2+1" or "3+1" method is mentioned, as this is more common for subjective clinical interpretations.
• Clinical Data (Literature Review): The "adjudication" for the literature review involved the selection and interpretation of published studies relevant to "clinical in vivo experience of a stent within the clinical indication that we are requesting." This implies a review process by the sponsor's clinical and regulatory teams. Specific adjudication methods (like expert panels re-reviewing individual patient data from the literature) are not described, which is typical for a literature-based justification in a 510(k).

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC comparative effectiveness study was not done. This type of study is more common for diagnostic imaging devices where reader performance is a key metric. This submission concerns an implantable therapeutic device, and the demonstration of effectiveness relies on mechanical performance and previously published clinical outcomes, not on human reader interpretation.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done

This question is not applicable to the WALLSTENT® Enteral Endoprosthesis, as it is a physical medical device, not an algorithm or AI software. Therefore, no standalone algorithm performance study was done.

7. The Type of Ground Truth Used

• For Mechanical Performance: Engineering specifications and established test standards.
• For Clinical Effectiveness (New Indication): Outcomes data derived from the published clinical literature regarding the use of similar stents (and the predicate stent) for the palliative treatment of malignant obstructions/strictures. This implicitly includes expert consensus from the medical community as reflected in published research.

8. The Sample Size for the Training Set

No specific "training set" in the context of machine learning or AI is mentioned because this device is a physical product, not dependent on an algorithm trained on data. The device's design is based on established engineering principles and prior experience with the predicate device.

9. How the Ground Truth for the Training Set Was Established

Not applicable, as there is no "training set" in the context of an algorithm. For the design and engineering principles, the "ground truth" is established through materials science, biomechanical engineering, and clinical experience gained from previous versions of the device (the predicate).

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The Schneider (USA) Inc Enteral Endoprosthesis is indicated for palliation of duodenal strictures caused by malignant neoplasms.

The WALLSTENT® Enteral Endoprosthesis is comprised of two components: the temporary (short-term) implantable metallic stent and the delivery device. The stent is composed of implant-grade cobalt-base superalloy wire braided in a tubular mesh configuration. The design configuration results in a stent that is flexible, compliant and The stent is available in multiple sizes. Physician preference and self-expanding. individual patient condition and/or anatomy will determine the appropriate size chosen.

This 510(k) submission for the WALLSTENT® Enteral Endoprosthesis does not contain a study that demonstrates the device meets acceptance criteria in the manner typically seen with AI/ML devices or new medical technologies requiring extensive clinical trials for performance validation. Instead, it relies on substantial equivalence to a predicate device and existing clinical literature.

Here's an analysis based on the provided text, addressing your specific points where possible:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample Size for Test Set and Data Provenance

• Sample Size: Not applicable in the context of a prospective clinical trial on the new device. The performance validation relies on tests performed on the predicate device and a review of clinical literature.
• Data Provenance: The device's performance is supported by:
  • Mechanical tests performed on the predicate device.
  • A "search of clinical literature" suggesting successful clinical in vivo experience of metal stents in the duodenal area (retrospective, likely international but not specified).

3. Number of Experts and Qualifications for Ground Truth

• Number of Experts: Not applicable. Ground truth, in this context, refers to the established safety and efficacy of the predicate device and general clinical experience with similar devices, not a new clinical evaluation for this specific device.
• Qualifications of Experts: N/A for establishing a specific ground truth for a test set of the device itself. The regulatory body (FDA) and the applicant's internal assessments rely on medical and scientific expertise.

4. Adjudication Method for the Test Set

• Adjudication Method: Not applicable. The submission does not describe a test set requiring adjudication in the sense of expert consensus on diagnostic or outcome data for the new device. The FDA's review process itself involves expert evaluation.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

• MRMC Study: No. This submission pre-dates widespread AI/ML applications in medical devices and does not involve human readers interpreting data assisted by an AI. The device is a physical stent.

6. Standalone Performance Study (Algorithm Only)

• Standalone Performance Study: No. This is a physical medical device (stent), not an algorithm or software-only device.

7. Type of Ground Truth Used

The "ground truth" for this submission is multi-faceted, relying on:

• Predicate Device Performance Data: Mechanical test results (fatigue, corrosion, radial force, deformation) on the legally marketed predicate device.
• Clinical Outcomes Data (from literature): Successful clinical in vivo experience with similar metal stents in decompressing strictures and relieving gastric outlet obstruction, as reported in published clinical literature.
• Engineering Equivalence: The assessment that the new device has identical materials, construction, and processing as the predicate.

8. Sample Size for the Training Set

• Sample Size: Not applicable. This is not a machine learning device and therefore does not have a "training set" in that context. The "training" for the device's design and manufacturing comes from the predicate device and established engineering principles.

9. How Ground Truth for the Training Set Was Established

• How Ground Truth Established: Not applicable. As above, there is no "training set" in the AI/ML sense. The "ground truth" of what constitutes a safe and effective stent for the intended use is established through:
  • Years of clinical experience with similar devices.
  • Regulatory standards for materials and mechanical performance.
  • The proven performance and safety profile of the predicate device.

Summary Explanation:

This 510(k) submission leverages the concept of substantial equivalence. The applicant argues that the WALLSTENT® Enteral Endoprosthesis is equivalent to an already legally marketed device (the WALLSTENT® devices and specifically an existing Enteral Endoprosthesis) because:

1. It is made of identical materials and has identical construction and processing.
2. It introduces no new materials, design, or manufacturing processes.
3. Performance testing conducted on the predicate device demonstrated mechanical strength (fatigue, corrosion, radial force, deformation) within expected ranges, which is considered applicable to this new device due to their identical nature.
4. A review of clinical literature supports the successful use of metal stents in the duodenal area for the intended palliative treatment of strictures.

Therefore, the "proof" that the device meets acceptance criteria is not a new clinical study directly assessing the performance of this specific device against predefined clinical endpoints. Instead, it's an assertion of sameness to a device already deemed safe and effective, supported by indirect evidence from the predicate and general clinical experience. The FDA's acceptance (indicated by the 510(k) clearance letter) confirms their agreement with this claim of substantial equivalence.

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