Minimum volumes for TAVI: Better prospects of success with larger case volumes

In a series of commissions awarded by the Federal Joint Committee (G-BA) to the Institute for Quality and Efficiency in Health Care (IQWiG), the question is whether for certain surgical procedures, a correlation can be shown between the volume of services provided per hospital and the quality of treatment results. IQWiG's rapid report on transcatheter aortic valve implantation (TAVI) is now available.

According to the findings, a positive correlation can be inferred between the volume of services and the quality of treatment results for TAVI: In hospitals with larger case volumes, patients undergoing surgery have higher survival probabilities, fewer bleeding events, fewer longer-term postoperative ventilations, and fewer hospital readmissions.

The number of TAVIs is increasing; the number of open surgeries is decreasing

The medical indication for TAVI is usually a substantial narrowing of the heart valve (aortic valve stenosis), especially in elderly patients with a medium or high surgical risk, for whom open surgical valve replacement would be very risky. The narrowing of the valve obstructs the flow of blood from the heart and causes shortness of breath. TAVI involves replacing the diseased heart valve via a vascular access. In this procedure, the replacement valve is mounted on a stent frame and folded together. The replacement valve is advanced to the aortic valve and placed on the diseased aortic valve, which is then expanded.

Since 2007, the number of TAVIs performed annually in Germany has increased considerably, while the number of open aortic valve replacement surgeries has decreased: In 2019, more than 21,000 aortic valves were replaced using TAVI and more than 8,400 using open surgery.

For TAVI, the G-BA has not yet established minimum volume standards for the provision of services in hospitals. However, the consensus paper published in 2020 by the German Cardiac Society and the German Society for Thoracic, Cardiac and Vascular Surgery already requires minimum volumes for TAVI as part of the certification process: At least 50 implantations per year per hospital and at least 25 implantations per year per individual interventional cardiologist must be demonstrated for certification.

Positive correlation between case volumes and survival probabilities

IQWiG included eight retrospective observational studies in its assessment of the volume of services and quality of treatment results for TAVI. None of the studies contained findings of a high informative value.At the hospital level, the studies show a positive correlation between volume of services and quality of treatment results for the following outcomes:

• “all-cause mortality” and “in-hospital mortality” as well as
• “bleeding”, “postoperative ventilation for more than 48 hours” and “hospital readmission”

At the physician level, a positive association between volume of services and treatment results can only be derived for “in-hospital mortality”.

For TAVI, IQWiG found no meaningful studies examining the effects of specific minimum case volumes introduced into the health care system on the quality of treatment results.

Process of report production

In October 2020, the G-BA commissioned IQWiG to prepare the report on the correlation between the volume of services and the quality of treatment results for TAVI in an accelerated procedure as a so-called rapid report. Interim products were therefore not made available for a hearing. This rapid report was sent to the contracting agency, the G-BA, on 30 June 2021 and has now been published.

An English-language extract of the rapid report will be available soon. If you would like to be informed when this document is available, please send an e-mail to info@iqwig.de.