R-015-005 Investigator's Brochure Legit.Health_acne
Table of contents
- Introduction
 - Identification of the Investigator's Brochure (IB)
 - Sponsor/Manufacturer
 - Investigational device information
- Summary of the literature and evaluation supporting the rationale for the design and intended use of the investigational device
 - Statement concerning the regulatory classification of the investigational device
 - General description of the investigational device
 - Summary of relevant manufacturing processes and related validation processes
 - Manufacturer's instructions for installation (installation maintenance, storage requirements, manipulation)
 - Sample of the label (for example sticker or copy, and instructions for use or reference to, and information on any training required).
 - Description of the intended clinical performance
 
 - Preclinical testing
- Design calculations
- The user receives quantifiable data on the intensity of clinical signs
 - The user receives quantifiable data on the count of clinical signs
 - The user receives quantifiable data on the extent of clinical signs
 - The user receives an interpretative distribution representation of possible ICD categories represented in the pixels of the image
 
 - Validation of software relating to the function of the device
 - Performance tests
- Test: If something does not work, the API returns meaningful information about the error
 - Test: Notify the user image modality and if the image does not represent a skin structure
 - Test: Notify the user if the quality of the image is insufficient
 - Test: The user specifies the body site of the skin structure
 - Test: We facilitate the integration of the device into the users' system
 - Test: The data that users send and receive follows the FHIR healthcare interoperability standard
 - Test: The user authentication feature is functioning correctlyç
 - Test: Ensure all API communications are conducted over HTTPS
 - Test: Ensure API compliance with Base64 image format and FHIR standard
 - Test: Verification of authorised user registration and body zone specification in device API
 - Test: Ensure API stability and cybersecurity of the medical device
 
 
 - Design calculations
 - Existing clinical performance data
- Summary of relevant previous clinical experience with the investigational device: (Information on clinical data generated by the manufacturer)
- Optimisation of clinical flow in patients with dermatological conditions using Artificial Intelligence.
 - Pilot study for the clinical validation of an artificial intelligence algorithm to optimise the appropriateness of dermatology referrals.
 - Clinical validation study of a Computer-aided diagnosis (CADx) system with artificial intelligence algorithms for early non-invasive detection of in vivo cutaneous melanoma.
 - Clinical Validation of a Computer-Aided Diagnosis (CAD) System Utilising Artificial Intelligence Algorithms for Continuous and Remote Monitoring of Patient Condition Severity in an Objective and Stable Manner.
 - Project to enhance Dermatology E-Consultations in Primary Care Centres using Artificial Intelligence Tools.
 - Non-Invasive Prospective Pilot in a Live Environment for the improvement of the diagnosis of Generalised Pustular Psoriasis
 - Non-invasive prospective Pilot in a Live Environment for the improvement of the diagnosis of skin pathologies in primary care
 - Non-invasive prospective Pilot in a Live Environment for the Improvement of the diagnosis of skin pathologies in primary care and dermatology
 
 - Analysis of adverse device effects and any history of modification or recall
 
 - Summary of relevant previous clinical experience with the investigational device: (Information on clinical data generated by the manufacturer)
 - Investigational device risk management
 
Introduction
This Investigator's Brochure (IB) provides essential information regarding a medical device to support investigators in understanding its characteristics, intended use, and clinical application.
The purpose of this document is to compile relevant preclinical and clinical data, safety information, and regulatory considerations related to the device.
The device is a computational software-only medical device leveraging computer vision algorithms to process images of the epidermis, the dermis and its appendages, among other skin structures. Its principal function is to provide a wide range of clinical data from the analysed images to assist healthcare practitioners in their clinical evaluations and allow healthcare provider organisations to gather data and improve their workflows.
Identification of the Investigator's Brochure (IB)
Title of the clinical investigation
Pilot study for the clinical validation of a medical device for the automatic severity assessment and remote monitoring of patients with acne.
Investigational device
Legit.Health Plus (hereinafter, the device)
IB Reference Number
Legit.Health_acne Investigator's Brochure
Protocol code
Legit.Health_acne_V6
Confidentiality statement
This Study Investigator's Brochure is the property of the manufacturer. and is a confidential document. It must not be copied or distributed to other parties without prior written authorisation from the manufacturer.
Principal Investigator
- José Luis López Estebaranz
 - Clínica DermoMedic
 - C. de Jorge Juan, 36
 - 28001 Madrid
 - Tel: 915769054
 
Sponsor/Manufacturer
| Manufacturer data | |
|---|---|
| Legal manufacturer name | AI Labs Group S.L. | 
| Address | Street Gran Vía 1, BAT Tower, 48001, Bilbao, Bizkaia (Spain) | 
| SRN | ES-MF-000025345 | 
| Person responsible for regulatory compliance | Alfonso Medela, Saray Ugidos | 
| office@legit.health | |
| Phone | +34 638127476 | 
| Trademark | Legit.Health | 
Investigational device information
Summary of the literature and evaluation supporting the rationale for the design and intended use of the investigational device
The existing literature on acne and severity assessment highlights the need for accurate diagnostic tools, given the complexity of its presentation and the variability in its severity and impact. Acne is a common skin disorder caused by the dysfunction of sebaceous glands, leading to clogged pores and various types of lesions in areas rich in sebaceous glands, such as the face and forehead. Affecting up to 80% of adolescents, acne has significant psychological repercussions, often contributing to low self-esteem, anxiety, and depression, which in turn can lower the quality of life to levels comparable to chronic illnesses.
Current tools for assessing acne severity, such as lesion counting and the Investigator Global Assessment (IGA), face challenges related to subjectivity and time demands. For instance, while lesion counting is precise, it is labor-intensive and impractical for routine clinical use. Other methods, like the Global Acne Grading System (GAGS), are detailed but complex, making it difficult to ensure consistency both between observers and within the same observer. There is no universally standardised and widely accepted scoring method, leading to inconsistencies in clinical evaluations and limited comparability between studies.
Recent advances in image processing and AI-based systems have introduced automated tools that address these limitations. Studies by Chantharaphaichi et al. and Maroni et al. have shown promising results in automated acne detection and assessment. In this context, the manufacturer has developed ALADIN, an AI-powered system integrated into the device. Retrospective validation of ALADIN has demonstrated its effectiveness. The goal of this study is to clinically validate ALADIN, potentially offering a standardised, time-efficient, and reliable solution for assessing acne severity. This advancement could improve treatment timelines and outcomes for patients while promoting consistency in clinical practice. Additionally, it paves the way for future research on treatment efficacy and deeper insights into the pathophysiology of acne.
- Williams HC, Dellavalle RP, Garner S. Acne vulgaris. Lancet. 2012 Jan 28;379(9813):361-72. doi: 10.1016/S0140-6736(11)60321-8.
 - Kircik LH. Androgens and acne: perspectives on clascoterone, the first topical androgen receptor antagonist. Expert Opin Pharmacother. 2021 Sep;22(13):1801-1806. doi: 10.1080/14656566.2021.1918100.
 - Tan JK, Bhate K. A global perspective on the epidemiology of acne. Br J Dermatol. 2015 Jul;172 Suppl 1:3-12. doi: 10.1111/bjd.13462.
 - Samuels DV, Rosenthal R, Lin R, Chaudhari S, Natsuaki MN. Acne vulgaris and risk of depression and anxiety: A meta-analytic review. J Am Acad Dermatol. 2020 Aug;83(2):532-541. doi: 10.1016/j.jaad.2020.02.040.
 - Agnew T, Furber G, Leach M, Segal L. A Comprehensive Critique and Review of Published Measures of Acne Severity. J Clin Aesthet Dermatol. 2016 Jul;9(7):40-52.
 - Chantharaphaichi, T., Uyyanonvara, B., Sinthanayothin, C., & Nishihara, A. (2015). Automatic acne detection for medical treatment. 2015 6th International Conference of Information and Communication Technology for Embedded Systems (IC-ICTES), 1-6.
 
Statement concerning the regulatory classification of the investigational device
Currently, the device is undergoing the accreditation process to obtain the European CE marking. Once this is achieved, the attached declaration included in this document will be signed. For now, it serves as an example of a declaration of conformity with national regulations.
The device complies with the applicable standards:
- UNE-EN ISO 13485:2018 (EN ISO 13485:2016) Medical devices - Quality management systems - Requirements for regulatory purposes
 - UNE-EN 62304:2007/A1:2016 (EN 62304:2006/A1:2015) Medical device software - Software life-cycle processes
 - UNE-EN ISO 14971:2020 (EN ISO 14971:2019) Medical devices - Application of risk management to medical devices
 - UNE-EN ISO 15223-1:2022 (EN ISO 15223-1:2021) Medical devices - Symbols to be used with information to be supplied by the manufacturer - Part 1: General requirements
 - UNE-EN ISO 20417:2021 (EN ISO 20417:2021) Medical devices - Information to be supplied by the manufacturer
 - UNE-EN 62366-1:2015/A1:2020 (EN 62366-1:2015/A1:2020) Medical devices - Part 1: Application of usability engineering to medical devices
 - UNE-EN ISO 14155:2021 (EN ISO 14155:2020) Clinical investigation of medical devices for human subjects - Good clinical practice
 
There are no common specifications applicable to the device.
Complies with the provisions of the Regulation (EU) 2017/745 of the European Parliament and of the Council on Medical Devices and issued under the exclusive responsibility of AI Labs Group SL.
- Classification: Class IIb (Rule 11)
 
The conformity assessment route is based on a quality management system and on assessment of technical documentation according to the Annex IX (Chapters I and III) of the above mentioned regulation.
- Certificate ID: MDR 792790
 - Notified body: BSI (British Standards Institution) number 2797.
 
All documentation supporting this CE Declaration of Conformity is preserved in the document management system of the manufacturer, supported by the Quality System approval to ISO 13485 by BSI.
General description of the investigational device
The device is a medical product that operates solely as computational software, utilising advanced computer vision algorithms to analyse images of the epidermis, dermis, and associated skin structures. Its primary function is to generate a comprehensive range of clinical data from the analysed images, supporting healthcare professionals in their clinical assessments and enabling healthcare provider organisations to gather data and optimise their workflows.
The data produced by the device is intended to assist both healthcare professionals and organizations in their clinical decision-making processes, enhancing the efficiency and accuracy of care delivery.
It is important to note that the device is not designed to confirm a clinical diagnosis. Instead, its output serves as one component of a broader clinical evaluation. The device is specifically intended to be used when a healthcare professional seeks additional information to support their decision-making process.
Summary of relevant manufacturing processes and related validation processes
As a software medical device, the manufacturing process does not involve traditional physical production but follows a structured software development lifecycle (SDLC) aligned with regulatory and quality standards, including ISO 13485:2016, IEC 62304:2006/A1:2015, and ISO 14971:2019. The applicable legislation includes:
- Medical Device Regulation (MDR) 2017/745
 - UNE-EN ISO 13485:2018 (EN ISO 13485:2016) Medical devices. Quality management systems. Requirements for regulatory purposes.
 - UNE-EN 62304:2007/A1:2016 (EN 62304:2006/A1:2015) Medical device software. Software life cycle processes.
 - UNE-EN ISO 14971:2020 (EN ISO 14971:2019) Medical devices. Application of risk management to medical devices.
 - UNE-EN ISO 15223-1:2022 (EN ISO 15223-1:2021) Medical devices. Symbols to be used with information to be supplied by the manufacturer. Part 1: General requirements.
 - UNE-EN ISO 20417:2021 (EN ISO 20417:2021) Medical devices. Information to be supplied by the manufacturer.
 - UNE-EN 62366-1:2015/A1:2020 (EN 62366-1:2015/A1:2020) Medical devices. Part 1: Application of usability engineering to medical devices.
 
The development and maintenance of the software follow agile methodologies, ensuring continuous integration, verification, and validation. The process includes:
- Requirement analysis and specification: Defined according to clinical needs and risk management principles.
 - Software design and architecture: Developed following modular and scalable design principles.
 - Implementation and coding: Conducted in a controlled environment with version control and secure coding practices.
 - Software verification and validation: Conducted through unit testing, integration testing, system validation, and clinical performance evaluation.
 - Deployment and release: Includes controlled distribution through validated channels, ensuring integrity and cybersecurity compliance.
 
The validation processes ensure that the device meets its intended purpose, complies with MDR (Regulation (EU) 2017/745), and follows good software engineering practices. Key validation activities include:
- Software Verification and Testing
 - Clinical Validation
 - Risk Management and Usability Validation
 - Regulatory Compliance and Documentation
 
The manufacturing process adheres to rigorous software development and validation standards, ensuring safety, accuracy, and reliability. Continuous post-market surveillance and performance evaluation further ensure compliance with regulatory requirements and ongoing clinical validation.
Manufacturer's instructions for installation (installation maintenance, storage requirements, manipulation)
Due to its software nature, there is no maintenance required.
Regarding its Lifetime, the expected operational lifetime of the device is established at 5 years, which is subject to regular software updates and the lifecycle of the integrated components and platforms. The lifetime will be increase in equivalent spans as the design and development continues and maintenance and re-design activities are carried out.
This timeline accounts for the expected evolution of the underlying operating systems and tools, the progression of medical device technology, and the necessary update cycles to maintain security and operability.
As regards the installation of the device, this is mostly established in the Instructions for use. Although the device offers various integration methods tailored to the specific use case and client requirements. For this study, researchers will access the device through its web app, ensuring a seamless and straightforward experience. Since the platform is web-based, researchers can log in from any browser, whether on a mobile device or a computer.
Each researcher will receive a unique set of credentials: a username and a corresponding password—allowing them to securely access their professional account on the device web app. Once logged in, they will be able to create patient profiles, upload lesion photographs, and input any relevant clinical information as needed.
For this study, no additional installation or complex setup will be required to use the device.
Sample of the label (for example sticker or copy, and instructions for use or reference to, and information on any training required).
- Device name: Legit.Health Plus
 - European Medical Device Nomenclature (EMDN) coding: Z12040192 (General medicine diagnosis and monitoring instruments - Medical device software)
 - Global Medical Device Nomenclature (GMDN) coding: 65975
 - Risk Classification according to EU MDR 2017/745: Class IIb
 
| Symbol | Meaning | Information | 
|---|---|---|
| Unique Device Identifier | (01)8437025550005(10)1.0.0.0(11)YYYYMMDD | |
| Version | (10) 1.0.0.0 | |
| Manufacture date | (11) (YYYYMMDD) | |
| Manufacturer | AI Labs Group SL BAT Tower, Gran Vía 1, 48001, Bilbao, Biscay (Spain)  | 
| Symbol | Meaning | 
|---|---|
eIFU  | Consult electronic instructions for use | 
| Caution | |
DRAFT  | EU MDR 2017/745 CE marking (DRAFT) | 
| Medical Device | 
In case of observing an incorrect operation of the software, notify the manufacturer as soon as possible at: support@ legit.health. The manufacturer will proceed accordingly. Any serious incident related to the device must be reported both to the manufacturer and the competent authority in the Member State where the user or patient is located.
It is not known or foreseen any undesirable side-effects specifically related to the use of the software.
Description of the intended clinical performance
Intended use
The device is a computational software-only medical device leveraging computer vision algorithms to process images of the epidermis, the dermis and its appendages, among other skin structures, enhancing efficiency and accuracy of care delivery, by providing:
- an interpretative distribution representation of possible International Classification of Diseases (ICD) categories that might be represented in the pixels content of the image
 - quantifiable data on the intensity, count and extent of clinical signs such as erythema, desquamation, and induration, among others
 
Quantification of intensity, count and extent of visible clinical signs
The device provides quantifiable data on the intensity, count and extent of clinical signs such as erythema, desquamation, and induration, among others; including, but not limited to:
- erythema,
 - desquamation,
 - induration,
 - crusting,
 - xerosis (dryness),
 - swelling (oedema),
 - oozing,
 - excoriation,
 - lichenification,
 - exudation,
 - wound depth,
 - wound border,
 - undermining,
 - hair loss,
 - necrotic tissue,
 - granulation tissue,
 - epithelialization,
 - nodule,
 - papule
 - pustule,
 - cyst,
 - comedone,
 - abscess,
 - draining tunnel,
 - inflammatory lesion,
 - exposed wound, bone and/or adjacent tissues,
 - slough or biofilm,
 - maceration,
 - external material over the lesion,
 - hypopigmentation or depigmentation,
 - hyperpigmentation,
 - scar
 
Image-based recognition of visible ICD categories
The device is intended to provide an interpretative distribution representation of possible International Classification of Diseases (ICD) categories that might be represented in the pixels content of the image.
Device description
The device is a computational software-only medical device leveraging computer vision algorithms to process images of the epidermis, the dermis and its appendages, among other skin structures. Its principal function is to provide a wide range of clinical data from the analyzed images to assist healthcare practitioners in their clinical evaluations and allow healthcare provider organisations to gather data and improve their workflows.
The generated data is intended to aid healthcare practitioners and organizations in their clinical decision-making process, thus enhancing the efficiency and accuracy of care delivery.
The device should never be used to confirm a clinical diagnosis. On the contrary, its result is one element of the overall clinical assessment. Indeed, the device is designed to be used when a healthcare practitioner chooses to obtain additional information to consider a decision.
Intended medical indication
The device is indicated for use on images of visible skin structure abnormalities to support the assessment of all diseases of the skin incorporating conditions affecting the epidermis, its appendages (hair, hair follicle, sebaceous glands, apocrine sweat gland apparatus, eccrine sweat gland apparatus and nails) and associated mucous membranes (conjunctival, oral and genital), the dermis, the cutaneous vasculature and the subcutaneous tissue (subcutis).
Intended patient population
The device is intended for use on images of skin from patients presenting visible skin structure abnormalities, across all age groups, skin types, and demographics.
Intended user
The medical device is intended for use by healthcare providers to aid in the assessment of skin structures.
User qualifications and competencies
This section outlines the qualifications and competencies required for users of the device to ensure its safe and effective use. It is assumed that all users already possess the baseline qualifications and competencies associated with their respective professional roles.
Healthcare professionals
No additional official qualifications are required for healthcare professionals (HCPs) to use the device. However, it is recommended that HCPs possess the following competencies to optimize device utilization:
- Proficiency in capturing high-quality clinical images using smartphones or equivalent digital devices.
 - Basic understanding of the clinical context in which the device is applied.
 - Familiarity with interpreting digital health data as part of the clinical decision-making process.
 
The device may be used by any healthcare professional who, by virtue of their academic degree, professional license, or recognized qualification, is authorized to provide healthcare services. This includes, but is not limited to:
- Medical Doctors (MD, MBBS, DO, Dr. med., or equivalent)
 - Registered Nurses (RN, BScN, MScN, Dipl. Pflegefachfrau/-mann, or equivalent)
 - Nurse Practitioners (NP, Advanced Nurse Practitioner, or equivalent)
 - Physician Assistants (PA, or equivalent roles such as Physician Associate in the UK/EU)
 - Dermatologists (board-certified, Facharzt für Dermatologie, or equivalent)
 - Other licensed or registered healthcare professionals as recognized by local, national, or European regulatory authorities
 
Each HCP must hold the academic title, degree, or professional registration that confers their status as a healthcare professional in their jurisdiction, whether in the United States, Europe, or other regions where the device is provided.
IT professionals
IT professionals are responsible for the technical integration, configuration, and maintenance of the medical device within the healthcare organization's information systems.
No specific official qualifications are mandated. Nevertheless, it is advisable that IT professionals involved in the deployment and support of the device have the following competencies:
- Foundational knowledge of the HL7 FHIR (Fast Healthcare Interoperability Resources) standard and its application in healthcare data exchange.
 - Ability to interpret and manage the device's data outputs, including integration with electronic health record (EHR) systems.
 - Understanding of healthcare data privacy and security requirements relevant to medical device integration, including GDPR (Europe), HIPAA (US), and other applicable local regulations.
 - Experience with troubleshooting and supporting clinical software in a healthcare environment.
 - Familiarity with IT standards and best practices for healthcare, such as ISO/IEC 27001 (Information Security Management) and ISO 27799 (Health Informatics—Information Security Management in Health).
 
IT professionals may include, but are not limited to:
- Health Informatics Specialists (MSc Health Informatics, or equivalent)
 - Clinical IT System Administrators
 - Healthcare Integration Engineers
 - IT Managers and Project Managers in healthcare settings
 - Software Engineers and Developers specializing in healthcare IT
 - Other IT professionals with relevant experience in healthcare environments, as recognized by local, national, or European authorities
 
Each IT professional should possess the relevant academic degree, professional certification, or demonstrable experience that qualifies them for their role in the healthcare organization, in accordance with the requirements of the United States, Europe, or other regions where the device is provided.
Use environment
The device is intended to be used in the setting of healthcare organisations and their IT departments, which commonly are situated inside hospitals or other clinical facilities.
The device is intended to be integrated into the healthcare organisation's system by IT professionals.
Operating principle
The device is computational medical tool leveraging computer vision algorithms to process images of the epidermis, the dermis and its appendages, among other skin structures.
Body structures
The device is intended to use on the epidermis, its appendages (hair, hair follicle, sebaceous glands, apocrine sweat gland apparatus, eccrine sweat gland apparatus and nails) and associated mucous membranes (conjunctival, oral and genital), the dermis, the cutaneous vasculature and the subcutaneous tissue (subcutis).
In fact, the device is intended to use on visible skin structures. As such, it can only quantify clinical signs that are visible, and distribute the probabilities across ICD categories that are visible.
Explainability
For visual signs that can be quantified in terms of count and extent, the underlying models not only calculate a final value, such as the number of lesions, but also determine their locations within the image. Consequently, the output for these visual signs is accompanied by additional data, which varies depending on whether the quantification involves count or extent.
- Count. When a visual sign is quantifyed by counting, the device generates bounding boxes for each detected entity. These bounding boxes are defined by their x and y coordinates, as well as their height and width in pixels.
 - Extent. When a visual sign is quantifyed by its extent, the device outputs a mask. This mask, which is the same size as the image, consists of 0's for pixels where the visual sign is absent and 1's for pixels where it is present.
 
The explainability output can be found with the explainabilityMedia key. Here is an example:
{
  "explainabilityMedia": {
    "explainabilityMedia": {
      "content": "base 64 image",
      "detections": [
        {
          "confidence": 98,
          "label": "nodule",
          "p1": {
            "x": 202,
            "y": 101
          },
          "p2": {
            "x": 252,
            "y": 154
          }
        },
        {
          "confidence": 92,
          "label": "pustule",
          "p1": {
            "x": 130,
            "y": 194
          },
          "p2": {
            "x": 179,
            "y": 245
          }
        }
      ]
    }
  }
}
Preclinical testing
Design calculations
The user receives quantifiable data on the intensity of clinical signs
Objective
This study aims to demonstrate that the quantification of clinical sign intensity provided by the algorithm performs at the level of expert dermatologists.
Acceptance Criteria
The algorithm must achieve a Relative Mean Absolute Error (RMAE) below 20%.
Materials & Methods
A dataset of 5,459 images depicting dermatological conditions was analysed by multiple dermatology experts to establish a gold standard. Each image was labeled with ordinal or categorical values, and the algorithm was trained based on the consensus among experts.
To ensure the dataset was sufficiently large, RMAE values were calculated and monitored. A stabilisation threshold of 0.02 in standard deviation was used to determine when additional data no longer significantly impacted performance. The final dataset was split into training, validation, and test sets using K-fold cross-validation. Expert agreement levels were assessed, yielding an RMAE of 13.8% and a Relative Standard Deviation (RSD) of 12.56%, confirming the dataset's adequacy.
Model Training & Evaluation
A set of multi-output deep learning classifiers was developed, each focused on a specific task. The models were based on EfficientNet-B0, a neural network architecture pre-trained on ImageNet. Training followed a transfer learning approach, initially freezing most layers and fine-tuning the entire model in later stages.
Tasks included estimating the intensity of various visual signs such as erythema, edema, desquamation, exudation and affected tissues. The models were evaluated using RMAE and balanced accuracy metrics.
Results of the test
The algorithms achieved strong performance, with an average RMAE of 13% for key clinical signs. All individual RMAE values remained below the 20% threshold, meeting the acceptance criteria. Performance highlights include:
- Erythema, edema, oozing, excoriation, lichenification, and dryness: RMAE of 13%.
 - Induration, desquamation, and pustulation: RMAE consistently below 20%.
 - Exudation, edges, and affected tissues: Balanced accuracy of 64%, 74%, and 69%, respectively.
 
Conclusions
The automatic quantification of clinical sign intensity by the algorithm is comparable to expert dermatologists, ensuring high-quality, reliable data to support clinical decision-making.
The user receives quantifiable data on the count of clinical signs
Objective
To assess whether the quantifiable data on the count of clinical signs provided to the user is extracted with expert dermatologist-level performance.
Acceptance Criteria
The algorithm's Mean Absolute Error (MAE) for detecting nodules, abscesses, and draining tunnels must be lower than that of the annotators or within a variance of less than 10%.
Hive detection must achieve precision and recall rates above 50%.
Inflammatory lesion detection must achieve precision and recall rates above 70%.
Materials & Methods
Ground Truth Generation
A total of 2,012 images were used, categorised as follows: hidradenitis suppurativa (221), acne (1,457), and urticaria (334). Expert dermatologists specialising in each condition reviewed the images (six for hidradenitis and five for urticaria). The ACNE04 dataset was pre-labeled, so no additional annotators were needed.
For hidradenitis suppurativa, a four-stage aggregation algorithm was developed, slightly favoring the most experienced and best-performing specialists to unify multi-label annotations. For urticaria, a different method was applied: individual bounding boxes were converted into Gaussian distributions and merged based on annotator consensus. These methods ensured accurate ground truth labels for training object detection models.
Data Splitting
After ground truth labels were generated, the datasets were split into training and validation sets. Given the limited dataset size, a train/validation split was chosen over a train/validation/test setup, with K-fold cross-validation applied to improve reliability. The ACNE04 dataset followed the original patient-wise stratified split, while hidradenitis and urticaria images were manually reviewed to prevent data leakage.
Model Training
Three main object detection tasks were defined, each trained with the YOLOv5 architecture:
- A model for detecting nodules, abscesses, and draining tunnels.
 - A model for detecting hives.
 - A model for detecting inflammatory lesions.
 
YOLOv5 was selected due to its strong balance between speed and accuracy. Transfer learning was applied, using pre-trained weights from ImageNet to enhance dermatology-related tasks. Once trained, these models can automatically detect and count lesions to compute severity scores (e.g., UAS and IHS4), categorising cases as “clear,” “mild,” “moderate,” or “severe.”
Results of the test
Nodule, Abscess, and Draining Tunnel Detection
The YOLOv5x model achieved MAE values of 2.16 (mild), 3.37 (moderate), and 5.26 (severe), closely matching dermatologist scores of 2.04, 3.01, and 4.88, respectively. The algorithm's variance (0.096) was significantly lower than the annotators' (1.57), well below the 10% deviation threshold.
Inflammatory Lesion Detection
The algorithm's MAE was 5.56, lower than the dermatologists' 7.5. Precision and recall exceeded the 70% threshold, with the best-performing model (YOLOv5m) achieving 73.5% precision and 74.17% recall.
Hive Detection
The best-performing model achieved an average precision of 68% and a recall of 57%. Mean Average Precision at IoU 0.5 (mAP@0.5) exceeded 0.60, confirming strong performance despite the task's complexity.
Protocol Deviations
No additional annotation was required for acne images.
Conclusions
The quantifiable data on clinical sign counts provided to users matches dermatologist expertise. This ensures the quality and consistency of training datasets, offering healthcare professionals reliable information to support clinical assessments.
The user receives quantifiable data on the extent of clinical signs
Objective
To assess whether the quantifiable data on the surface area of clinical signs provided to the user is extracted with expert dermatologist-level performance.