The IQWiG has just published draft version 6.1 of its “General methods”.
The General Methods describe the work procedures of the IQWiG, including the principles applied to the early benefit and method assessments. It includes detailed and transparent information on how the benefit and harm of medical drugs and procedures are determined.
In order to reflect the expanding tasks and further development of standards in the scientific disciplines, the IQWiG regularly updates this methods paper. These could be major updates, which will lead to a new version number or minor updates reflected in the decimals of the version number.
This minor update of version 6.1 focuses on 3 key topics:
- Evidence report
- New thresholds for determining the extent of additional benefit
- New concept for inferred effects
The draft version is currently available in German only. Comments on these updates and amendments can be submitted to the IQWiG by 4 Oct 2021.
Evidence report
In December 2019, the DVG law was introduced. This new law enables the AWMF to propose the development of certain clinical guidelines to the BMG. The BMG can then commission the IQWiG to support them in the development by gathering supportive evidence. The IQWiG will then produce evidence reports to summarize their findings and support the development of the clinical guidelines. This results in changes in chapters 1, 2 and 5 of the methods paper.
New thresholds for determining the extent of additional benefit
The methods paper includes information on how the extent of the additional benefit of a product is determined. Thereby, they differentiate between different kinds of data:
- binary (analyses of 2×2 tables)
- time to event (survival time analyses)
- continuous or quasi-continuous, in each case with available responder analyses (analyses of mean values and standard deviations)
- other (e.g. analyses of nominal data)
The updated methods paper now changed the instructions for continuous data. The threshold values for SMD continue to be based on Cohen:
- small effects (SMD between 0.2 and 0.5)
- medium effects (SMD between 0.5 and 0.8) and
- large effects (SMD greater than 0.8).
The baseline for both serious and non-serious symptoms, which is required for a “minor” additional benefit remains the irrelevance threshold of SMD = 0.2. But the new methods update now lowered the thresholds for SMDs for a “major” and “considerable” extent for continuous outcomes.
New concept for inferred effects
Inferred effects mean that the available data allow an effect to be derived, even though an effect can’t be estimated across all studies.
- For heterogeneous data, inferred effects corresponds with uni-directional effects.
- For homogeneous data, the updated IQWiG method now also allow to apply inferred effects.