In the 2010 Medicare Physician Fee Schedule, CMS says they'll develop a new, two-digit modifier to identify the admitting physician in a hospital. CMS has yet to deliver the modifier to you and your peers, but there's a fair amount of speculation that it will be AI.
To back up a second, CMS states in the PDF of the rule:
"Because of an existing CPT coding rule and current Medicare payment policy regarding the admitting physician, we will create a modifier to identify the admitting physician of record for hospital inpatient and nursing facility admissions. For operational purposes, this modifier will distinguish the admitting physician of record who oversees the patient's care from other physicians who may be furnishing specialty care. The admitting physician of record will be required to append the specific modifier to the initial hospital care or initial nursing facility care code which will identify him or her as the admitting physician of record who is overseeing the patient's care. Subsequent care visits by all physicians and qualified NPPs will be reported as subsequent hospital care codes and subsequent nursing facility care codes."
CMS did not include the two-digit modifier in the fee schedule, but you'll find AI listed as a new modifier in CMS's HCPCS update for 2010. The description for the modifier is "Principal physician of record." Sounds like it could be used for distinguishing the admitting physician, no?
In an email to Part B News, CMS says they'll release the modifier, well ... when they release the modifier. So, don't plan on using AI just yet - but, there's a chance this will be the modifier you'll use come Jan. 1.