Effects of minimum volume regulations are unclear

In principle, regression models are the most suitable way to calculate and establish minimum volumes. However, no clear trend regarding the effects of such minimum volumes on the quality of treatment can be identified from the currently available data. This is mainly because there are only a few studies and their quality is mostly inadequate. This is the conclusion of the report by the German Institute for Quality and Efficiency in Health Care (IQWiG) published on 28th June 2012.

Highly specialized procedures and particular diseases

For certain diseases, patients can be treated at a hospital without being admitted. These include, on the one hand, highly specialized procedures that generally require a particular piece of technical equipment and, on the other, the treatment of rare diseases such as cystic fibrosis, or diseases such as HIV that follow a particular course.

Up to now, those medical services that hospitals can provide on an out-patient basis have been set out in a directive by the Federal Joint Committee (G-BA), which also defined certain minimum volumes and other criteria. That means a hospital must reach a certain number of cases of the particular intervention - be it an operation or a diagnostic procedure - in order for the hospital to be able to continue to perform them on an out-patient basis and charge for them. Since the Versorgungsstrukturgesetz (Structure of Health Care Act) came into force in 2012, these services, which are now called "specialist care", can also be provided by community-based physicians.

IQWiG was commissioned by the G-BA to examine which methods are particularly suitable for calculating and establishing minimum volumes. IQWiG was also asked to investigate how specifying such case numbers affects the quality of treatment.

Regression models best suited

To answer the first question, IQWiG searched for national and international publications and found a total of 32 primary studies (retrospective observational studies), 6 systematic reviews and 3 papers on methodology. The Institute established that approaches which model the individual patient data using certain regression models are, in principle, best suited to determine thresholds for minimum volumes.

Contradictory effects for key outcomes

As regards the second question - the effects of minimum volume regulations on the quality of treatment - IQWiG was able to evaluate 10 studies. These were largely based on administrative data from hospitals and on hospital surveys. Overall, IQWiG rates the evidence base as poor, because most of the few studies available have a very high risk of bias and therefore their informative value is low.

In terms of effects on mortality, symptoms and late complications, as well as the need for further medical procedures, the available study data showed contradictory effects. Hence, no uniform trend could be derived for any of these outcomes.

None of the studies looked at the quality-assuring or quality-increasing effects of minimum volumes for those medical services and procedures that could up to now be performed and charged for on an out-patient basis in German hospitals.

Procedure of report production

The Federal Joint Committee (G-BA) commissioned IQWiG to prepare the report in an accelerated process, known as a "rapid report". Unlike the normal procedure, no preliminary reports are published in this case. Although a draft version of the report is reviewed by external experts, no hearing at which all interested parties can comment takes place. The report was compiled and sent to the contracting agency at the end of May 2012.

The following English-language executive summary provides an overview of the background, procedure and further results of the report.

Contact: Tel. +49(0)221-35685-0, info@iqwig.de