Breast feeding in the first six months.

clinically or similar in their use of resources.6For this reason a programme to amend diagnosis related groups was initiated,7 and a new set of groupings (healthcare resource groups) are now available for use in resource management sites.These will be further developed over the next few years.Until now case mix groupings in the NHS have been used only in managing resources in hospital.The internal market, however, requires a common set of treatment groups for use in contracting between purchasers and providers.These groups will have to be capable of identifying the population's health care needs and assembling them into packages that providers can offer to meet.Although final decisions have yet to be made, the logic of using one of the available case mix groupings seems compelling.For it to be workable, however, the appropriateness of the groupings will have to be acceptable to doctors.Much work needs to be done to ensure that the groups are both clinically meaningful and homogeneous in their use of resources.In addition, work is needed to extend their use beyond the acute inpatient sector.Finally, it should be understood that the purpose of the analysis determines the method of grouping.For resource management and setting and monitoring contracts it may be right to use a grouping based on groups that consume similar resources.An isoresource grouping, however, is not neces- sarily useful for examining the quality and outcomes of care.For this purpose groupings of patients with a similar prog- nosis or severity of disease (iso-outcome groups) are needed.Grouping case mix by diagnosis related group may be useful to identify exceptional costs and lengths of stay but is unlikely to be very useful for audit and quality assurance.For these purposes severity ofillness systems, such as disease staging8 or patient management categories,9 may be more useful.