Conceptual and practical difficulties with the economic evaluation of health services developments.

Five recent economic evaluations comparing hospital at home schemes with acute hospital care faced remarkably similar problems. This paper outlines these problems and considers what strategies can be derived from these experiences, which will be relevant to economic evaluations of other aspects of the organisation of care, particularly those crossing the interfaces between primary and secondary health care or the interface between health and social services. The difficulties experienced can be divided into conceptual and practical problems. Conceptual problems were primarily associated with issues of context and related to the choice of comparator, capacity constraints and size of schemes, and the choice between a short or a long run perspective. Practical problems were connected with the time at which schemes were evaluated, the type of clinical study alongside which studies were conducted and the types of data available for use in the analysis. Strategies which can be pursued in conducting economic evaluations of organisational change include giving greater attention to conceptual and hence contextual problems as well as reporting these contextual issues in detail, accepting the need for repeated economic evaluations as organisational changes become more widespread and considering carefully the clinical study design where economic evaluations of organisational change are conducted alongside. These strategies are of importance not just to those conducting economic evaluations but also to those funding appraisals of changes in the organisation of care. Use of different strategies such as those suggested here should be evaluated.