For the first time in its history, Medicare will soon track spending on millions of individual beneficiaries, reward hospitals that hold down costs and penalize those whose patients prove most expensive.

The administration plans to establish "Medicare spending per beneficiary" as a new measure of hospital performance, just like the mortality rate for heart attack patients and the infection rate for surgery patients.

Hospitals could be held accountable not only for the cost of the care they provide, but also for the cost of services performed by doctors and other health care providers in the 90 days after a Medicare patient leaves the hospital.

This plan has drawn fire from hospitals, which say they have little control over services provided after a patient's discharge - and, in many cases, do not even know about them. More generally, they are apprehensive about Medicare's plans to reward and penalize hospitals based on untested measures of efficiency that include spending per beneficiary.