Economic appraisal of new technology in the absence of survival data--the case of total hip replacement.

The development of total hip replacement has reached a level at which little further improvement in pain relief or quality of life can be expected from the introduction of new prosthetic technology. Rather, it is reasonable to expect longer trouble-free prosthetic life. This paper develops a mathematical model for a comparative economic appraisal of two types of prostheses, the conventional cemented one and the new cementless one. The lack of reliable survivorship data precludes reaching definite conclusions. However, by extensive sensitivity analysis with respect to a number of cost parameters the model can be used to derive conditions under which the cementless prosthesis is more cost effective. Expert medical judgement can then be used to gage whether these conditions are likely to be satisfied. The paper highlights the importance of collecting statistically valid performance data on any new medical technology from its first introduction. Without these, its full-scale adoption will be based largely on subjective grounds rather than a proper cost benefit analysis. It finally shows how both aspects--economic modeling and scientific data collection--form part of an integrated management programme for the economic evaluation of new medical technology.