Quality in numbers

Behind every number is a child, a family, an individual destiny. That is why it is particularly important to us to present our results openly and transparently – in a way that is understandable and comprehensible. Because numbers alone do not tell the whole story – only their context reveals how good the treatment really is.

What do case numbers tell us?

First and foremost, a high number of operations means a wealth of experience. But the type of procedures performed is also a decisive factor. A center that primarily operates on simple heart defects will naturally have low complication rates and very low mortality rates. At the DHZC, on the other hand, we also treat many very complex cases—including patients for whom no other treatment options are available elsewhere. That is why it is important to always consider case numbers in relation to the complexity of the procedure in question. 

Proven quality—year after year

All of our results are continuously fed into the ECHSA database (European Congenital Heart Surgeons Association) – one of the largest and most renowned international quality databases for pediatric heart surgery. It now contains over 380,000 operations on more than 300,000 patients from 50 countries worldwide. The DHZC is the only center in Germany that has been participating in this database without interruption since 2012 and has its data validated externally every year. 

The data is transmitted anonymously and evaluated by independent experts. Every operation, every diagnosis, every complication is included. Only a few centers worldwide meet the requirements for annual certification – we have been one of them for many years. This gives our patients and their parents the assurance that our quality data is not only collected internally, but also independently verified.

Expected vs. actual mortality

How high is the risk of a child dying during a particular operation? This question can be answered statistically – based on thousands of comparable procedures recorded in the ECHSA database. An “expected mortality rate” is calculated for each procedure, depending on the degree of difficulty of the procedure. The more complex the procedure, the higher this expected value. 

The two graphs show the correlation between expected and actual mortality rates at a large number of pediatric heart surgery centers. The X-axis shows the expected mortality rate—i.e., the calculated risk depending on the complexity of the procedure. The Y-axis shows the actual mortality rate observed at the DHZC. Each circle represents a center, with the size of the circle corresponding to the volume of treatment. Our center is highlighted in red.

Graph 1 shows the values based on over 6,600 operations performed between 2012 and 2023. Based on the complexity of the cases, an average mortality rate of 4.7 percent would have been expected here. The mortality rate actually recorded at the DHZC was well below this at 2.4 percent, making our center the best in comparison to other centers in the database.

Given the continuous improvement in treatment methods, this figure is even better when only the approximately 1,900 operations performed between 2020 and 2023 are evaluated, as shown in Figure 2: Due to the complexity of the operations performed, an average mortality rate of 4.9 percent would have been expected here – but the actual mortality rate measured was only 1.8 percent.