Unlike Social Security, where benefits are tied in a mechanical fashion to retirees’ wage histories and we have some useful tools for forecasting future benefits, the possible variance in medical spending rises dramatically as we move into the next decade and beyond. As with Social Security, forecasting the number of Medicare beneficiaries is reasonably straightforward.
But we know very little about how rapidly medical technology will continue to advance and how those innovations will translate into future spending. Technological innovations can greatly improve the quality of medical care and can, in some instances, reduce the costs of  BIS Review 49/2004  3  existing treatments.