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.

Beginning in 2005, Florida changed the format of their physician identifiers. The identifiers cannot be used to link to data from previous years

Also, Florida provided three types of physician IDs:

1. Attending Physician ID Number in MDNUM1_R,
2. Operating or Performing Physician ID Number in MDNUM2_R and
3. Other Physician ID Number in MDNUM3_R.

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 2017, Kentucky replaced the two consulting practitioner NPI numbers by the referring practitioner NPI (HCUP MDNUM3) and the patient's family practitioner NPI (HCUP MDNUM4).

Beginning in 2012, Kentucky supplies two additional consulting practitioner NPI numbers that are saved as HCUP data element MDNUM3 and MDNUM4.

Beginning October 2009, only NPIs accepted as valid IDs for both facilities and clinicians.

In Kentucky two types of physician identifiers are available:

1. Attending physician is provided in MDNUM1_R and
2. Physician that performed the primary procedure is provided in MDNUM2_R.

Physician identification numbers may not accurately track physicians within and across hospitals. Kentucky collects two different types of physician identifiers, National Provider Identifier (NPI) and state license numbers.

In Oregon, four types of physician identifiers are available:

1. Attending Clinician is provided in MDNUM1_R,
2. Operating room Clinician is provided in MDNUM2_R,
3. 1st Other Clinician is provided in MDNUM3_R, and
4. 2nd Other Clinician is provided in MDNUM4_R.

MDNUM3_R was not supplied or available for 2011.

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