Skip Navigation

KID Description of Data Elements
The KID is set of longitudinal hospital inpatient databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
 
MDNUM1_R - Physician 1 number (re-identified)
 
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
General Notes
 

HCUP encrypted physician identifiers are referred to by different names in the HCUP data across years.

Year Variable
1988-2000 MDID_S
2001-2002 MDNUM1_S
Beginning with 2003 MDNUM1_R

MDNUM1_R is an arbitrarily chosen re-identified identifier for physicians created during HCUP data processing. If the original physician identifier is based on a state license number or Universal Physician Identification Number (UPIN), then MDNUM1_R can be used to track a physician across hospitals. If the original physician identifier is based on hospital-specific identifiers, then it can only be used to track physicians within a hospital. Except in those data sources where physician license numbers are supplied, it is not known whether the physician identifier refers to individual physicians or to groups. MDNUM1_R cannot be linked to any external database in order to obtain additional physician characteristic information.Refer to state-specific notes for more information about the type of physician identifiers provided by each state.

Because of a change in the algorithm for creating a masked physician number, physicians cannot be tracked from before 2003 to after 2003. In HCUP data prior to 2003, a synthetic physician number (MDNUM1_S prior to 2003 and MDID_S prior to 2001), created using fixed-key encryption, was available. Starting in data year 2003, a reidentification number (MDNUM1_R) was used.

 
Top
 
Uniform Values
VariableDescriptionValueValue Description
MDNUM1_RPhysician 1 number (re-identified)9(n)Physician identifier
.Missing
 
Top
 
 
State Specific Notes

Arkansas

In Arkansas data, four types of physician identifiers are available:

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

Physician identification numbers may not accurately track physicians within and across hospitals. Arkansas provides Universal Physician Identification Numbers (UPINs) and state license numbers. The provided physician identifiers are encrypted during HCUP processing. Beginning in 2008, Arkansas also provides National Provider Identifier.



Arizona

Beginning in 2008, Arizona provides the National Provider Identifier (NPI). This prohibits using MDNUMn to track physicians in HCUP data prior to 2008.

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.

Prior to 2008, Arizona provided two types of physician identifiers:

  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 across hospitals for the following reasons:

  • Some hospitals assign their own internal physician identification numbers rather than using the license numbers issued by the licensing agency of the physician or other health care practitioner. Information was not available about the prevalence of this practice.
  • Some hospitals use one physician identification number for several physicians that are part of the same physician practice group. Information was not available about the prevalence of this practice.

The physician identification number includes license numbers from the following board of examiners: Medical, Osteopathic, Podiatrists, and Nurses. In addition, Arizona accepts licensing numbers from other health practitioner licensing boards, but these boards are unspecified. The provided physician identifiers are encrypted during HCUP processing.



Colorado

In Colorado two types of physician identifiers are available:

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

Physician identification numbers may not accurately track physicians across hospitals. The state encourages hospitals to use the Professional State License Number as an identifier, but some hospitals continue to use their own internal identification number. Also, some hospitals appear to pad the Professional State License Number (a 5-digit code). Information was not available from the data source about the prevalence of these practices.


Some hospitals may use one license number for all physicians in order to protect physician confidentiality. Information was not available from the data source about the prevalence of this practice. The provided physician identifiers are encrypted during HCUP processing.

Beginning in 2012, Colorado changed the encryption of their physician identifiers. Because of this change, MDNUMn_R cannot be used to link to data from previous years.



Florida

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.

In 2006, Florida changed the format of their physician identifiers. The identifiers cannot be used to link to data from previous years.

Beginning in 2005, 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 (new in 2005).

Prior to 2005, Florida provided two types of physician identifiers (re-identified):

  1. Attending physician is provided in MDNUM1_R and
  2. Operating physician is provided in MDNUM2_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.

Caution should be used when tracking physicians across 2003. The physician identifiers supplied by the data source do not conform to the documented pattern. Not all identifiers included a two-character prefix, and not all had the same length.



Georgia

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

  1. Attending physician is provided in MDNUM1_S,
  2. 1st other physician is provided in MDNUM2_S and
  3. 2nd other physician is provided in MDNUM3_S
  4. 3rd other physician is provided in MDNUM4_S.

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.



Iowa

Beginning in 2007, Iowa reports the National Provide Identifier (NPI) or the Universal Physician Identification Numbers (UPIN).

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).

Physician identification numbers may be used to track physicians within and across hospitals. Prior to 2007, Iowa reports Universal Physician Identification Numbers (UPINs). The provided physician identifiers are encrypted during HCUP processing.

Beginning in 2011, only the NPI is retained by Iowa in the physician fields. If a valid NPI is not available, a generic ID is used.



Kansas

In Kansas two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R and
  2. Primary surgeon is provided in MDNUM2_R.

Physician identification numbers may be used to track physicians within and across hospitals. Kansas reports Universal Physician Identification Numbers (UPINs) and state license numbers for the physician identifiers.



Kentucky

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.



Maine

In Maine, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R.
  2. Operating surgeon is provided in MDNUM2_R.

Maine provides state-specific encrypted physician identifier numbers that allow for tracking physicians within and across hospitals. The provided physician identifiers are encrypted again during HCUP processing.


Caution should be used when tracking physicians back to 1999 inpatient data. The encrypted values supplied by the data source in the 1999 inpatient data contained slightly different coding than the values supplied beginning in the 2000 inpatient and ambulatory surgery data.



Maryland

In Maryland, two types of physician identifiers are available:

  1. Attending physician NPI is provided in MDNUM1_R and
  2. Operating physician NPI is provided in MDNUM2_R.

Physician identification numbers can be used to track physicians within and across hospitals.

Prior to 2009, MDNUM1 and MDNUM2 contained state license numbers assigned by the Maryland State Medical Society (MedChi). Source documentation describes strict assignment and verification rules for this field.

State license numbers are available in MDNUMOTHER1-2 starting in 2009

From 2003-2005, physician identifiers were encrypted by the state of Maryland. Beginning in 2006, the encryption occurs during HCUP data processing.

Prior to 2003, the supplied physician identifiers were unencrypted.



Michigan

Beginning in 2012, Michigan provides the National Provider Identifier (NPI).

Beginning in 2007, a few Michigan hospitals changed the format of their physician identifiers. This change will render their physician identifiers incomparable to previous years.

In Michigan, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R and
  2. Primary surgeon is provided in MDNUM2_R.

Physician identification numbers do not accurately track physicians across hospitals. Michigan reports hospital-specific physician identifiers. During HCUP processing, physician identifiers were encrypted.



Minnesota

In Minnesota, three types of physician identifiers are available:

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

The physician identifiers may not accurately track physicians within and across hospitals. Minnesota provides a combination of Universal Physician Identification Number (UPIN), state license numbers, and hospital-specific numbers. During HCUP processing, this number is encrypted.



Missouri

In Missouri, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R and
  2. Primary surgeon is provided in MDNUM2_R.

Physician identification number may not accurately track physicians within and across hospitals. Missouri accepts National Provider Identifiers (NPIs), Universal Physician Identification Numbers (UPINs), state license numbers, and hospital-assigned physician identification numbers. According to the source, the majority of physician identifiers are UPINs.



Nebraska

In Nebraska, two physician identifiers are available:

  1. Primary physician is provided in MDNUM1_R and
  2. Secondary physician in MDNUM2_R.

Physician identification numbers may not accurately track physicians across hospitals. The state encourages hospitals to code Universal Physician Numbers (UPINs) as an identifier, but some hospitals continue to use the Professional State License Number.



Nevada

In Nevada, two types of physician identifiers are available:

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

Physician identification numbers can be used to track physicians within and across hospitals. Nevada provides the physician's state license number. During HCUP processing, this number is encrypted.

Beginning in 2008, Nevada provides state license numbers and UPIN.

Beginning in 2010, encrypted NPI is in MDNUM1_R and MDNUM2_R.



New Hampshire

About 6-7 percent of missing values of re-identified physician 1 number in the 2006 New Hampshire SID were categorized in non-blank.

In New Hampshire, four types of physician identifiers are available:

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

Physician identification numbers can be used to track physicians within and across hospitals. New Hampshire reports the Universal Physician Identification Number (UPIN). During HCUP processing, this number is re-identified to protect the confidentiality of the physician.



New Jersey

Beginning in 2017, four types of physician identifiers are available:

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

Physician identification numbers may not accurately track physicians within and across hospitals. During HCUP processing, physician identifiers are encrypted. The coding of the physician identification number varies across years:

Year Physician Identifier
1988-93 New Jersey state license numbers
1994-95 Universal Physician Identification Numbers (UPINs)
1996-2008 New Jersey state license numbers.
Beginning in 2008 New Jersey National Provider Identifiers (NPIs)

Beginning in 2008, attending physician state license numbers are contained in MDNUMOTHER1.



New Mexico

New Mexico changed from Physician code to NPI in July 1, 2008 and changed from six-character length to ten-character length.

In New Mexico, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R
  2. Operating physician is provided in MDNUM2_R

Physician identification numbers can be used to track physicians within and across hospitals.



New York

Beginning with the 2005 data, physician identifiers are missing (" ") on discharges with an indication of an induced abortion. New York identifies an indication of induced abortion by ICD-9-CM diagnosis or procedure code:

  • An admitting, principal, or secondary diagnosis of "6350" through "6399", or "7796".
  • A principal or secondary procedure of "690", "695", "696", "6993", "738", "7491", "750", or "9649".

For the 2001 - 2004 data, physician identifiers are missing (" ") on discharges with an indication of an induced abortion. New York identifies an indication of induced abortion by ICD-9-CM diagnosis or procedure code:

  • An admitting, principal, or secondary diagnosis of "6350" through "6399", or "7796".
  • A principal or secondary procedure of "690", "695", "696", "6993", "738", "7491", "750", "751", or "9649".

Please note that the admitting diagnosis is not retained in the HCUP databases.

In New York, 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.

Physician identification numbers can be used to track physicians within and across hospitals. New York reports state license numbers as physician identifiers. Source documentation indicates that if the reported physician number did not possess a valid New York state license number, the license number of the Chief of Service should have been reported.

New York does not limit this field to physicians; dentists, podiatrists, psychologists, nurse/midwives, and other licensed health care professionals may be included. It is impossible to identify the different types of providers in the HCUP data.

The provided physician identifiers are encrypted during HCUP processing.



North Dakota

In North Dakota, two types of physician identifiers are available starting in 2017:

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

Physician identification numbers can be used to track physicians within and across hospitals. North Dakota provides the national provider identifier (NPI).

Prior to 2017, North Dakota, four types of physician identifiers, which vary in their availability within each data year:

  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

The physician identifiers may not accurately track physicians within and across hospitals. North Dakota provides a combination of Universal Physician Identification Number (UPIN), state license numbers, and hospital-specific numbers. During HCUP processing, this number is encrypted.



Oregon

In Oregon, three types of physician identifiers are available; they added a fourth type and changed the label of their physician identifiers beginning in 2008:

  1. Attending physician (beginning in 2008, attending clinician) is provided in MDNUM1_R,
  2. 1st other physician (beginning in 2008, 1st other clinician) is provided in MDNUM2_R,
  3. 2nd other physician (beginning in 2008, 2nd other clinician) is provided in MDNUM3_R, and
  4. Operating room clinician is provided in MDNUM4_R.

Beginning in 2008, Oregon switched to NPI because it helps them identify the physicians better.

Physician identification numbers may not accurately track physicians across hospitals. Beginning in the 1997 data files, Oregon supplied the physician identifier number. Oregon encourages hospitals to use Universal Physician Identification Numbers (UPINs), but not all hospitals do. Information was not available from the data source about the prevalence of this practice. During HCUP processing, the physician identifiers were encrypted.



Pennsylvania

Beginning in 2017, National Provider Identification numbers are used for HCUP physician numbers. Prior to 2017, Pennsylvania state license numbers were used.

Beginning in 2011, Pennsylvania provides four physician identifiers:

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

From 2008 - 2010, Pennsylvania provided two types of physician identifiers:

  1. Attending physician is provided in MDNUM1_R and
  2. Operating physician is provided in MDNUM2_R.

Physician identification numbers can be used to track physicians within and across hospitals. Pennsylvania reports the state license numbers. The provided physician identifiers are encrypted during HCUP processing.

Through 2003, Pennsylvania provided three types of physician identifiers:

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

Physician identification numbers can be used to track physicians within and across hospitals. Pennsylvania reports the state license numbers. The provided physician identifiers are encrypted during HCUP processing.



Rhode Island

In Rhode Island, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R,
  2. Principal surgeon is provided in MDNUM2_R.

Physician identification numbers may not accurately track physicians across hospitals. Rhode Island provides blinded, hospital-specific numbers that cannot be linked to individual physicians. During HCUP processing, the provided physician identifiers are encrypted.



South Carolina

In South Carolina, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R and
  2. Other physician is provided in MDNUM2_R.

Physician identification numbers can be used to track physicians within and across hospitals. South Carolina reports six-character state license numbers. When the source values were shorter than six characters, the HCUP value was padded to bring it into conformity with South Carolina's format before the value was encrypted.



South Dakota

In South Dakota, three types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R
  2. Physician who performed the principal procedure is provided in MDNUM2_R
  3. Other physician is provided in MDNUM3_R.

Physician identification numbers can be used to track physicians within and across hospitals. Prior to 2007, South Dakota provides the Universal Physician Identification Numbers (UPINs).

From 2007-2009, South Dakota provides the National Provider Identifier (NPI) or the Universal Physician Identification Number (UPIN).

Beginning in 2010, South Dakota provides only the National Provider Identifier (NPI). Because of a change in the way the source encrypts physician identifiers, physicians cannot be tracked from before 2010 to after 2010.

Beginning in 2014, the data source no longer provides a third physician identifier.



Tennessee

In Tennessee, three types of physician identifiers are available:

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

Physician identification number may not accurately track physicians within and across hospitals. Tennessee collects two different types of physician identifiers from hospitals: Universal Physician Identification Numbers (UPINs) and state license numbers. The provided physician identifiers are encrypted during HCUP processing.



Texas

In Texas, 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_S (not available beginning in 2001).

Physician identification numbers can be used to track physicians within and across hospitals. Texas provides the state license numbers. During HCUP processing, the provided physician identifiers are encrypted.



Virginia

Beginning in 2008, Virginia provided 4 physician ID fields: attending physician IDs, operating physician IDs, other physician1 IDs, and other physician2 IDs. All fields include both UPIN and NPI.

In Virginia, four encrypted physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R;
  2. Operating physician that performed the first procedure is provided in MDNUM2_R;
  3. Other physician 1 and other physician 2 are available in MDNUM3_R and MDNUM4_R.

Physician identification numbers can be used to track physicians within and across hospitals. Prior to 2007, Virginia only reported Unique Physician Identification Numbers (UPINs). Beginning in 2007, Virginia accepted 2 different physician ID numbers in these fields: UPIN and NPI. The inclusion of NPI increased the frequency of physician ID numbers provided in these fields. During HCUP processing, the reported physician identifiers are encrypted.



Washington

Washington changed their formats for physician numbers starting in 2009; they should all be NPIs.

In Washington, two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1_R and
  2. Other physician is provided in MDNUM2_R.

Physician identification numbers do not accurately track physicians within and across hospitals. Washington collects several different types of physician identifiers, depending on the type of identifier provided by the hospitals. Hospitals provide Medicaid, Universal Physician Identification Numbers (UPINs), and DOH/HPQAD license numbers as physician identifiers. During HCUP processing, the physician identifiers are encrypted.



Wisconsin

Beginning in 2013, Wisconsin provides the National Provider Identifier (NPI).

Wisconsin provides three types of physician identifiers:

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


Wyoming

In Wyoming two types of physician identifiers are available:

  1. Attending physician is provided in MDNUM1 and
  2. Physician that performed the principal procedure is provided in MDNUM2.

Physician identification numbers may not accurately track physicians within and across hospitals. Wyoming provides a combination of Universal Physician Identification Numbers (UPINs) and state license numbers. The provided physician identifiers are encrypted during HCUP processing.


 
Top
 
 

Internet Citation: HCUP KID Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). September 2008. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/vars/mdnum1_r/kidnote.jsp.
Are you having problems viewing or printing pages on this Website?
If you have comments, suggestions, and/or questions, please contact hcup@ahrq.gov.
Privacy Notice, Viewers & Players
Last modified 9/17/08