Technological innovations can greatly improve the quality of medical care and can, in some instances, reduce the costs of existing treatments. But because technology expands the set of treatment possibilities, it also has the potential to add to overall spending - in some cases, by a great deal.
Other sources of uncertainty - for example, the extent to which longer life expectancies among the elderly will affect medical spending may also turn out to be important. As a result, the range of future possible outlays per recipient is extremely wide. The actuaries' projections of Medicare costs are, perforce, highly provisional.