Quality assurance of the diagnosis of occupational type IV allergies

Status:

completed 09/2025

Aims:

Allergic contact dermatitis caused by type IV sensitisation is one of the most common occupational skin diseases. Only by identifying the triggering allergen preventive measures can be implemented in the form of targeted allergen avoidance, thereby preventing the development, recurrence or worsening of occupational disease (BK) No. 5101. Allergological diagnostics in the form of patch tests are therefore extremely important in occupational dermatology for detecting or ruling out type IV sensitisation. The constantly changing world of work with changing allergen exposure and the limited availability of commercial standardised test allergens pose a major challenge in allergy diagnostics. In order to close the resulting diagnostic gaps, patch testing of the patient's own material (especially occupational substances) is essential. This can also be used to identify new occupationally relevant contact allergens or new occupational exposures to already known contact allergens. However, such tests require a high level of expertise and care in their performance and documentation. This final report documents the results of project FB-0317b on quality assurance in the diagnosis of type IV allergies. The research project pursued the following objectives:

• Systematic evaluation of patch tests with substances specific to the patient (usually occupational substances) with the aim of quality assurance
• Improvement and standardisation of allergy diagnostics for occupational diseases
• Identification of previously little-known or new occupational allergens and potential candidate substances for future commercial test allergen preparations
• Identification of further research needs in the field of primary and secondary prevention of occupational contact dermatitis

Activities/Methods:

The study, conducted from 1 October 2020 to 31 October 2025, was approved by the Ethics Committee of the University of Osnabrück and comprised a retrospective-prospective analysis of 2,137 test documents in which patch tests with patient's own material were generally performed and documented in accordance with the Accident Insurance Fee Schedule for Physicians (UV-GOÄ) No. 379. Data was collected nationwide via the accident insurance providers (UVT), which submitted the test documentations. The data was transmitted in pseudonymised or anonymised form, systematically recorded in a database and evaluated on the basis of defined criteria. Regular quarterly video conferences with the participating UVTs supported the study process and helped to identify challenges, such as those posed by COVID-19 or changes in legislation. The data collected was analysed using descriptive statistics to assess the quality, content and gaps in allergy diagnostics.

Results:

Patch tests of patients' own material were recorded for a total of 2,137 insured persons; of these, 1,319 [61.7%] were tested in clinics, 665 [31.1%] were tested in practices, and 153 [7.2%] could not be assigned due to anonymisation. A total of 14,955 individual patch tests with patients' own material (usually occupational substances) were carried out on these insured persons and recorded as part of the research project. Protective gloves and skin care products used by the insured persons were tested most frequently. The evaluation of the quality criteria revealed considerable shortcomings. Various deficiencies in the quality of the tests and documentation were identified, including insufficient information on the tested product (e.g. manufacturer, kind of material etc.). In many cases, when the test reaction to a mixture of substances was positive, the individual substances were not broken down, which makes it difficult to identify new occupational allergens. Due to the quality deficiencies identified, 31.2% of tests in practices, 26.5% of tests without assignment (due to anonymisation) and 7.9% of tests in clinics can be assumed to have very limited or no diagnostic validity. All these analysed tests were billed to the statutory accident insurance providers.

Conclusions and relevance for the UVT: This research project identified serious shortcomings in the allergological diagnosis of contact allergies. It should be noted that a significant proportion of insured persons – in the cohort of ‘practices’ and ‘without assignment’ in almost one third of the tests – did not receive adequate diagnosis. While a higher overall test quality was observed in clinics, there are serious shortcomings in many practices with regard to the performance and documentation of tests. A key finding is the insufficient use of standardised test forms, which significantly impairs the validity of diagnostics. In order to improve allergological diagnostics, targeted education and training of the dermatologists performing the tests and non-medical staff is urgently needed. In addition, it seems sensible to establish or strengthen centres specialising in patch testing of patient-specific substances in order to ensure high-quality, standardised and meaningful diagnostics. In view of the considerable implications of patch testing, including in terms of insurance law, this means that the UVT must formulate clear quality requirements for test procedures and documentation and promote the implementation of these in occupational dermatology centres in order to avoid invalid test results and, consecutively, incorrect decisions. With regard to the standards to be observed, the UVT can refer to the S3-guideline on patch testing by the Association of Scientific Medical Societies (AWMF) and the ‘Recommendations for patch testing with patient’s own materials in occupational dermatology’ recently published by the researchers on the basis of the project results. Overall, the results of the DGUV research project FB-0317B open up a wide range of approaches for quality assurance, improvement of care and further research in occupational dermatological allergy diagnostics.

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