(66 days)
The SOZO Pro has the following uses:
For adult human patients at risk of lymphedema:
A bioimpedance spectroscopy device for use on adult human patients, utilizing impedance ratios that are displayed as an L-Dex ratio that supports the measurement of extracellular volume differences between the limbs and is presented to the clinician on an L-Dex scale as an aid to their clinical assessment of lymphedema.
The use of the device to obtain an L-Dex score is only indicated for patients who will have or who have had lymph nodes, from the axillary and/or pelvic regions, either removed, damaged or imadiated.
The SOZO Pro system consists of a connected hand and footplate with built-in stainless-steel electrodes, paired with an Android tablet over Bluetooth connection. An app ("SOZOapp"), supplied with the tablet, controls the functionality of the hardware, and supplies the bioimpedance measurement data to a database ("MySOZO") managed on an external cloud- hosted database. Patient weight is measured with load cells located in the SOZO Pro foot unit or can be hand entered.
Bioimpedance measurements require the patient's weight to be measured by a scale embedded in the base of the system or for the weight of the patient to be entered manually. Following the collection of the patient weight, the patient contacts the SOZO Pro with their bare hands and feet on stainless steel electrodes. The impedance measurement takes about 30 seconds, during which the SOZO Pro® system applies small levels of electrical energy (200µA RMS) to the body across 256 frequencies spaced from 3kHz to 1000kHz and measures the resulting voltage levels.
This FDA 510(k) summary doesn't provide detailed information on specific acceptance criteria and a comprehensive study designed to prove the device meets those criteria in terms of clinical performance. Instead, it focuses on verifying the modifications to an existing predicate device (SOZO) by showing that the new device (SOZO Pro) still performs comparably and meets regulatory standards for safety and fundamental performance.
Here's an analysis based on the provided text, highlighting what is and isn't available:
Acceptance Criteria and Reported Device Performance
The document does not present a formal table of clinical performance acceptance criteria and reported results. The "Performance Data" section primarily addresses engineering and regulatory compliance rather than direct clinical efficacy for its intended use (aid in clinical assessment of lymphedema).
The closest indications of acceptance criteria and performance relate to engineering and regulatory standards:
| Acceptance Criteria Type | Description | Reported Performance |
|---|---|---|
| Electrical Safety / EMC | Compliance with IEC 60601 (subparts -1, -1-2, and -1-6) | "SOZO Pro device meets electrical safety and EMC requirements, and CB certificate was granted for the system." |
| Software V&V | Compliance with ISO 62304; meeting acceptance criteria and performing as intended | "Software was verified and validated to meet acceptance criteria and perform as intended." |
| Biocompatibility | Compliance with ISO 10993 for a low risk, limited contact device | "Patient contact areas of SOZO Pro system passed biocompatibility testing with no failures reported as they are unchanged from the reference device." |
| Functional Performance (Core Measurement) | Outputs remained consistently accurate and precise when compared to predicate SOZO measurements using fixed loads | "Performance testing was undertaken using fixed loads and comparing modified SOZO Pro to predicate SOZO measurements to demonstrate that outputs remained consistently accurate and precise." (Specific metrics like accuracy/precision values are not provided in this summary, but the conclusion is that it met the standard of consistent output). |
| Weight Scale Verification | Compliance with NIST Handbook 44 (2022 Edition) and EU Directive 2014/31/EU | "Scale verification testing for SOZO Pro was performed... experienced no failures." |
Missing Information (and likely not present in a 510(k) Special submission for this type of modification):
The 510(k) Special is for modifying an existing cleared device. Therefore, a new, comprehensive clinical study demonstrating the clinical effectiveness of the L-Dex ratio itself (which was established for the predicate device) is usually not required. The focus is on showing the modifications do not negatively impact the established performance.
- Sample size used for the test set and the data provenance: Not explicitly stated for clinical performance as clinical effectiveness was likely established with the predicate device. For functional performance, "fixed loads" were used, implying a lab-based test, not a patient test set.
- Number of experts used to establish the ground truth for the test set and the qualifications of those experts: Not applicable as this 510(k) does not describe a clinical ground truth establishment study.
- Adjudication method: Not applicable.
- Multi-reader multi-case (MRMC) comparative effectiveness study: Not applicable. The device provides a quantitative L-Dex ratio, not an image for interpretation by multiple readers.
- Standalone (algorithm-only) performance: The device is a standalone algorithm that provides an L-Dex score. Its performance in generating this score consistently is implied by the functional testing ("outputs remained consistently accurate and precise").
- Type of ground truth used (expert consensus, pathology, outcomes data, etc.): For the clinical use of the L-Dex ratio as an aid in lymphedema assessment, this ground truth would have been established with the predicate device and is not detailed here. The current submission focuses on engineering verification.
- Sample size for the training set: Not applicable. This device uses a bioimpedance spectroscopy algorithm to derive an L-Dex ratio, not a machine learning model that typically requires a clinical training set in the sense of AI/deep learning. The "algorithm" here is physics-based.
- How the ground truth for the training set was established: Not applicable for the reasons above.
In summary: The provided 510(k) summary focuses on demonstrating that the modifications to the SOZO Pro (weight scale, hardware, software integration) do not compromise the established safety and performance of the original SOZO device. It confirms compliance with various engineering and regulatory standards but does not re-evaluate the clinical efficacy of "L-Dex ratio as an aid to clinical assessment of lymphedema" through a new clinical trial, as that was likely part of the original predicate device's clearance.
§ 870.2770 Impedance plethysmograph.
(a)
Identification. An impedance plethysmograph is a device used to estimate peripheral blood flow by measuring electrical impedance changes in a region of the body such as the arms and legs.(b)
Classification. Class II (special controls). The device, when it is a body composition analyzer which is not intended to diagnose or treat any medical condition, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9.