The article provides an overview of the authorization process for clinical trials involving medical devices to be conducted in Germany.

medical device regulations in Germany

The German regulating authority in the sphere of healthcare products (BfArM) has published a guidance document dedicated to statistical requirements for applications for authorization of a clinical trial on medical devices. The document describes the applicable regulatory requirements and also provides additional clarifications and recommendations to be taken into consideration by medical device manufacturers, study sponsors, and other parties involved to ensure compliance. 

At the same time, the authority is entitled to make changes to the guidance and recommendations provided, should such changes be reasonably necessary to reflect corresponding amendments to the underlying legislation.


First of all, the authority emphasizes the important role statistics plays in every phase of clinical trials involving medical devices, from meticulous planning to rigorous execution and evaluation. The primary objective is to substantiate the safety, efficacy, and reliability of these medical products. 

In order to uphold these standards, both national regulations and harmonized international norms require the integration of statistical methodologies as an essential component of clinical trial protocols.

BfArM on fast track (fees and glossary)2

Regulatory Background 

In accordance with established standards such as DIN EN ISO 14155 (Clinical investigation of medical devices in humans), specific provisions are outlined to ensure that statistical practices adhere to rigorous scientific principles. These guidelines are designed to harmonize practices across jurisdictions and emphasize the importance of statistical rigor in generating reliable clinical trial data. 

The Bundesoberbehörde, in alignment with these norms, recommends comprehensive considerations during the planning and implementation of statistical methodologies to ensure compliance and methodological rigor.

Required Information in the Trial Protocol

As explained by the authority, in order to meet regulatory and scientific requirements, clinical trial protocols must include detailed statistical planning:

  • Primary and Secondary Hypotheses: Each study must clearly define the primary and secondary hypotheses that will be tested. Distinctions are made between exploratory studies, which may not require formal hypothesis testing, and confirmatory studies, where hypothesis formulation is critical to defining study success criteria.
  • Null Hypothesis Formulation: Precise formulation of null hypotheses with specific distribution parameters is essential to maintain the integrity of statistical tests. Ambiguity in null hypothesis formulation can lead to inflated Type I error rates, compromising the validity of study conclusions.
  • Statistical Methods: Exact specification of statistical tests and analytical procedures is crucial, particularly in confirmatory studies. The choice of methods should be justified based on the study objectives and hypotheses to avoid post hoc alterations that could bias results.
  • Analysis Populations: The definition of analysis populations such as Intention-To-Treat (ITT), Per Protocol (PP), and Safety Data Sets (SDS) is critical. Each population definition should include clear criteria for inclusion and exclusion to ensure consistency and validity in data analysis.
  • Sample Size Calculations: Robust estimation of sample sizes involves considerations of statistical power, expected treatment effects, variability assumptions, and anticipated dropout rates. Accurate sample size determination is essential to ensure study results are sufficiently powered to detect clinically meaningful effects.

Significance Level and Study Power

The scope of the guidance also covers the aspects related to the significance level and study power. 

  • Significance Level: The standard significance level is typically set at 5%, ensuring a balance between Type I and Type II error rates. While most studies use two-sided tests, exceptions may justify one-sided tests with adjusted significance levels.
  • Dropout Rates: Anticipation and reporting of dropout rates, including incidence rates over time, are critical to assessing the impact of missing data on study outcomes.
  • Criteria for Success or Failure: Clear criteria must be established to determine the acceptance or rejection of primary hypotheses. This is particularly important in studies with multiple hypotheses, where each hypothesis should have predefined criteria for statistical significance.

Interim Analyses and Adaptive Designs

In addition to the above, the document explains the approach to be followed when it comes to interim analysis. 

  • Interim Analysis: Detailed protocols for interim analyses should be pre-specified, including decision-making rules and potential adjustments to significance levels. Blinded analyses ensure unbiased assessments, while the establishment of Data Monitoring Committees (DMC) may be necessary for oversight and decision-making.
  • Adaptive Designs: Adaptive trial designs require careful planning and justification to ensure that modifications do not compromise the validity of study results. Adjustments to sample sizes or study endpoints should be clearly documented and justified within the trial protocol.

Reporting and Amendments

According to the guidance, any deviations from the initial statistical plan, including amendments post-database lock, must be rigorously documented, justified, and dated. These amendments should also include an assessment of their potential impact on the validity and interpretability of study findings.

Subgroup Analysis and Data Handling

Other aspects addressed in the guidance include the approach to be applied when analyzing subgroups and handling the data pertaining to the investigation. 

  • Subgroup Analysis: Guidelines for the analysis of subgroups should be predefined to ensure consistency and avoid data-driven interpretations. Pre-specified subgroup analyses contribute to the robustness and reliability of study conclusions.
  • Data Handling: Procedures for handling missing, unused, or corrupted data should be conservative, prioritizing approaches that minimize bias and maintain the integrity of the ITT analysis. Clear documentation of data management procedures enhances transparency and reproducibility.


In summary, compliance with rigorous statistical principles is vitally important to ensure the methodological integrity and regulatory compliance of clinical trials involving medical devices. These guidelines provide a framework for researchers and sponsors to conduct studies that generate reliable evidence on the safety and efficacy of medical devices. The parties responsible for clinical investigations should implement these requirements when interpreting study outcomes, making informed decisions in healthcare, and contributing to advancements in medical technology with integrity and reliability in order to ensure the proper performance of medical devices allowed for marketing and use in the country; as well as the safety of patients.

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