Aim: German social law (§ 137 SGB V) established minimum levels for the annual volume of in-patient care. Especially the limits remain an issue of controversy. Since December 2003 an agreement between the partners in health care has defined the first volume limits. Little is known about the effects of these on health care. Based on in-patient data for the year 2001 from 82 % of the hospitals in Baden-Württemberg, the possible effects of different limits (e.g. set by the Leapfrog Group, EUSOMA, and the § 137 SGB V agreement) were studied and presented as scenarios. Method: For each procedure an ICPM-tracer was defined based on agreed standard codes (e.g. from diagnosis-related groups) if available. Results: For certain high-risk conditions or procedures, centralization has already taken place (organ transplantation, coronary bypass surgery). For others, hospitals with an annual volume below the minimum level make up between 20 % and 60 % of the care provided. For all procedures studied, departments exist which perform less than ten procedures of this kind annually (e.g. 47 % of the departments involved in oncological breast surgery). Hospitals performing less than five oesophagectomies per year carried out 36 % of such operations in 2001. Conclusions: The lack of high-quality data for all hospitals makes it difficult to anticipate the effects of defined volume limits. Taking these limitations into account, such scenarios may, however, be of support in the necessary debate and help to balance the effects and benefits. When defining the limits, if the base of evidence is weak, regional differences should be considered.
