Kidney transplantations: better results with larger case volumes

In complex surgery, is there a correlation between the volume of services provided per hospital and the quality of treatment results? This is the question addressed in eight commissions on minimum volumes that the Federal Joint Committee (G-BA) awarded to the Institute of Quality and Efficiency in Health Care (IQWiG). The IQWiG report is now available for the fifth intervention to be tested, kidney transplantations.

According to the findings, for kidney transplantations there is a correlation between the volume of services and the quality of treatment results: In hospitals with larger case volumes, the survival probabilities are higher up to one year after transplantation. No correlation between the volume of services and the quality of treatment results can be inferred for the outcome “transplant failure”.

The most common organ transplantation in Germany

In chronic kidney failure, which is mostly caused by diabetes or high blood pressure, kidney transplantation is the only treatment option besides dialysis. The organ is donated either as a post-mortem donation or as a living donation from direct relatives or people very close to the patient. Five years after transplantation, 78 percent of post-mortem kidney donations and 87 percent of living kidney donations still function in the new body (figures for Europe). Kidney transplantation is the most common organ transplantation in Germany: In 2018, doctors in Germany transplanted 1671 kidneys after post-mortem organ donation and 638 kidneys after living donation. The waiting list for a donor kidney included more than 7500 patients in the same year. The average waiting time for a kidney transplant is currently more than 8 years.

Currently, a minimum of 25 procedures per hospital location and year is required for kidney transplantations (including living donations) in Germany. In contrast to the regulation on the annual minimum volume for liver transplantations, organ removals are not counted as part of the number of procedures required to achieve the minimum volumes.

Positive correlation between volume of services and survival probability

The question as to whether hospitals with larger case volumes achieve better treatment results for kidney transplantations than hospitals with smaller case volumes can be answered affirmatively by IQWiG for the survival probabilities of patients on the basis of a short-term observation period: For all-cause mortality up to 12 months after transplantation, two of the three studies assessed in this context show a lower probability of dying with a higher volume of services, although the informative value of the results is low. The IQWiG researchers cannot infer such a correlation for medium-term all-cause mortality after 36 months, for which a US study had collected data. After analysing the data from two relevant studies, the Institute also sees no correlation overall between the volume of services and the quality of treatment results for the outcome “transplant failure”. No usable data were available for the outcomes “adverse effects of treatment”, “health-related quality of life” and “length of hospital stay”, so that no conclusions can be drawn here.

Since none of the included studies considered the individual volumes of services of the surgeons, it is also not possible to assess whether greater routine in kidney transplantations leads to better treatment results.

There are no studies on the effects of specific minimum case volumes introduced into the health care system for kidney transplantations. IQWiG can therefore draw no conclusions here either.

Process of report production

In February 2019, the G-BA commissioned IQWiG to prepare the report on the correlation between the volume of services and the quality of treatment results for kidney transplantations in an accelerated procedure as a so-called rapid report. Interim products were therefore not published or made available for a hearing. The work on the project started in August 2019. This rapid report was sent to the contracting agency, the G-BA, in April 2020.