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PREVENA 125 and PREVENA PLUS 125 Therapy Units manage the environment of closed surgical incisions and remove fluid away from the surgical incision via the application of -125mmHg continuous negative pressure. When used with legally marketed compatible dressings, PREVENA 125 and PREVENA PLUS 125 Therapy Units are intended to aid in reducing the incidence of seroma and, in patients at high risk for post-operative infections, aid in reducing the incidence of superficial surgical site infection in Class I and Class II wounds.

The PREVENA 125 and PREVENA PLUS 125 Therapy Units ("PREVENA pumps") are singleuse, compact and portable powered suction pumps. The therapy units are packaged with compatible sterile canisters (45 ml for PREVENA 125 or 150 ml for PREVENA PLUS 125) and sterile tubing set. The therapy units can be used with compatible, legally marketed wound dressings classified under 21 CFR 878.4780, such as the PEEL & PLACE dressing and the CUSTOMIZABLE dressing, which, when combined are referred to as the PREVENA Incision Management Systems ("PREVENA systems"). The PREVENA Incision Management Systems deliver a pre-set, continuous negative pressure of 125 mmHz to the incision site. The systems are intended to be applied to incision sites immediately after surgery for a minimum of 2 days up to a maximum of 7 days depending on the surgeon's preference. The therapy units can be used up to 192 hours, after which they will automatically shut off.

The provided text describes the regulatory evaluation of the PREVENA 125 and PREVENA PLUS 125 Therapy Units, focusing on clinical evidence from a systematic literature review and meta-analyses rather than a single, dedicated device performance study with specific acceptance criteria that would typically be seen for AI/ML devices. Therefore, a direct table of "acceptance criteria and reported device performance" as one might expect for a diagnostic AI/ML device is not explicitly present in the document.

However, based on the meta-analysis results and the FDA's granted indications for use, we can infer the "acceptance criteria" were met by demonstrating a favorable trend in reducing SSI and seroma, particularly in specific subgroups. The study essentially is the meta-analysis of existing clinical data.

Here's an interpretation of the information provided, structured to address your points, with explanations where direct parallels to AI/ML device criteria are not exact due to the nature of this submission (a device for wound therapy, not an AI/ML diagnostic).

Inferred Acceptance Criteria and Reported Device Performance (Based on Meta-Analysis Conclusion)

While explicit numerical acceptance criteria for a single study were not provided, the FDA's granting of the De Novo request signifies that the overall body of evidence from the meta-analysis met the regulatory standard for demonstrating safety and effectiveness for the specified indications. The "acceptance" was based on a "small but consistent trend" and "greater absolute percentage reduction" in specific high-risk populations.

• For Superficial Incisional SSI (all wounds analyzed for depth): OR of 0.19 (95% CI: 0.08, 0.46), showing a significant reduction. (5 studies)
• For Class I wounds: OR of 0.36 (95% CI: 0.24, 0.55) for overall SSI, consistent reduction. (11 studies)
• For Class II wounds: OR of 0.27 (95% CI: 0.11, 0.68) for overall SSI, consistent reduction. (3 studies)
• For high-risk patients (overall SSI): OR of 0.40 (95% CI: 0.27, 0.62). Greater absolute percentage reduction observed (5.5% in treatment vs. 12.9% in control vs. 4.2% vs. 5.8% in overall). (9 studies) |
  | Device demonstrates acceptable safety profile. | Similar Safety Profile to Conventional Dressings: No significant differences in Adverse Events (AEs) or Serious Adverse Events (SAEs) between PREVENA and control groups in the 3 studies that reported this data. Post-market data (7 years, hundreds of thousands of units shipped) consistent with anticipated AEs (skin irritation, blisters, pain, etc.), and no device-related SAEs. |
  | Non-clinical performance (pressure maintenance, exudate removal, alarms). | Device capable of maintaining -125±25 mmHg, removing simulated wound fluid, and alarms function as intended under worst-case scenarios. |
  | Usability demonstrated. | Usability testing showed intended users can operate the device (reviewed from prior 510(k) K141017). |

Study Details:

1. Sample sizes used for the test set and the data provenance:

   • Test Set Sample Size:
     • For SSI meta-analysis: 20 prospective studies, total of up to 6,403 evaluable patients (1,367 in PREVENA group, 5,036 in control group).
     • For Seroma meta-analysis: 7 prospective studies, total of 952 evaluable patients (366 in PREVENA group, 586 in control group).
   • Data Provenance: The data comes from a systematic literature review and meta-analyses of published and unpublished prospective clinical studies. The geographic origin of these individual studies is not explicitly stated but implied to be global as it's a literature search. The studies are prospective. Seven articles identified as retrospective were removed to minimize bias.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • Study Selection/Ground Truth Establishment:
     • Study Selection: Six (6) independent reviewers performed the initial study selection. A subset of two (2) independent reviewers assessed abstracts and manuscripts for inclusion/exclusion criteria. When discordance was identified, these two reviewers deliberated until a consensus was reached.
     • Characteristic Extraction: At least two additional independent reviewers extracted study characteristics.
     • Wound Classification (Ground Truth for Subgroup Analysis): CDC wound classification was assigned to each study by "two individuals with appropriate medical and clinical trials background."
   • Qualifications: The specific qualifications (e.g., number of years of experience, board certification) of these reviewers/experts are not detailed beyond "independent reviewers" and "individuals with appropriate medical and clinical trials background."

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

   • Study Selection: "When discordance was identified, the two reviewers deliberated until a consensus was reached." This suggests a consensus-based adjudication among the two reviewers, rather than a third expert "tie-breaker" (2+1).
   • Wound Classification: "a CDC wound classification was assigned by two individuals with appropriate medical and clinical trials background." It is implied a consensus or adjudication method was used if there was disagreement, but not explicitly stated.

4. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • No, an MRMC study was NOT done. This submission is for a medical device (a wound therapy unit), not an AI/ML diagnostic or assistive technology for human readers. The study is a meta-analysis of clinical trials comparing the device to conventional wound dressings. Therefore, the concept of "human readers improving with AI assistance" is not applicable here.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Not applicable. This is a physical wound therapy device, not a standalone algorithm. Its performance is evaluated in a clinical context on patients.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • The "ground truth" for effectiveness (reduction in SSI and seroma) was the clinical outcomes data reported directly by the individual prospective studies included in the meta-analysis. These outcomes were typically assessed by the clinical investigators of each respective study.

7. The sample size for the training set:

   • Not applicable. This is a device, not an AI/ML model that requires a training set. The "training data" in a broader sense would be all the accumulated medical knowledge and device design iterations that led to the PREVENA system. The studies reviewed form the evidence base for its effectiveness, not a training set for an algorithm.

8. How the ground truth for the training set was established:

   • Not applicable. As stated above, there is no AI/ML training set in this context.

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