Beginning in 2008, Arizona provides the National Provider Identifier (NPI).

In Arizona three types of physician identifiers are available:

1. Attending physician is provided in MDNUM1_R,
2. Operating physician is provided in MDNUM2_R, and
3. Other physician is provided in MDNUM3_R.

Beginning in 2017, Akansas provides the National Provider Identifier (NPI) for the type of physician identifier.

In Arkansas, four types of physician identifiers are available:

1. Attending physician is provided in MDNUM1_R
2. Other physician in MDNUM2_R
3. Second other physician in MDNUM3_R, and
4. Third other physician in MDNUM4_R

In data year 2018, the source data provided by the HCUP Partner was missing a leading digit from some of the physician identification numbers. This will impact the reidentified value.

In District of Columbia, four types of physician identifiers are available:

1. Attending physician is provided in MDNUM1
2. Other physician in MDNUM2
3. Second other physician in MDNUM3, and
4. Third other physician in MDNUM4.

District of Columbia provides a combination of National Provider Identifier (NPI) and Universal Physician Identification Number (UPIN).

Beginning in 2010, Florida provides two identifiers for each physician. The new physician IDs are now housed in MDNUMn_R. Because of this change, MDNUMn_R cannot be used to link to data from previous years.

Three types of physician IDs are provided:

1. Attending Practitioner,
2. Operating or Performing Practitioner, and
3. Other Operating or Performing Practitioner.

Florida provides three types of physician identifiers.

1. MDNUM1 represents attending physician,
2. MDNUM2 represents operating or performing physician, and
3. MDNUM3 represents other physician.

Physician identification numbers may be used to track physicians within and across hospitals. Florida reports state license numbers for the physician identifiers. During HCUP processing, physician identifiers were encrypted.

In Georgia four types of physician identifiers are available beginning 2008:

1. Attending physician is provided in MDNUM1_R,
2. 1st other physician is provided in MDNUM2_R,
3. 2nd other physician is provided in MDNUM3_R, and
4. 3rd other physician is provided in MDNUM4_R.

Physician identification numbers may not accurately track physicians within and across hospitals. Prior to 2008, either the physician's state license number or the Universal Physician Identification Number (UPIN) were used to identify the physician. Beginning 2008, the national provider identification numbers (NPI) is provided. The provided physician identifiers are encrypted during HCUP processing.

In Iowa three types of physician identifiers are available:

1. Attending physician is provided in MDNUM1_R.
2. Physician that performed the principal procedure is provided in MDNUM2_R.
3. Referring physician is provided in MDNUM3_R (beginning 7/1/13).

Beginning in 2013, three types of physician identifiers are available:

1. Attending physician is provided in MDNUM1_R
2. Operating physician is provided in MDNUM2_R
3. Referring physician is provided in MDNUM3_R

In Utah, four types of physician identifiers are available. Beginning in 2018, the available fields are documented below:

1. Attending physician is provided in MDNUM1_R
2. Operating physician is provided in MDNUM2_R
3. Other 1 is provided in MDNUM3_R
4. Other 2 is proivded in MDNUM4_R

Beginning in 2015, Utah documentation indicates that this field contains the National Provider Identifier (NPI).

Prior to 2018, four types of physician identifiers are available:

1. Attending physician is provided in MDNUM1_R
2. Operating physician is provided in MDNUM2_R
3. Referring physician is provided in MDNUM3_R
4. Rendering physician is proivded in MDNUM4_R