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_S contains a fixed-key (one-to-one) encryption of the supplied physician 1 number (MDNUM1), according to the following rules:
- All alphanumeric digits are used in the encryption.
- All symbols such as ".,:;'*@" are retained in the encrypted value, but not in the same location.
- Leading zeros are encrypted so that the two original physician identifiers "000A6" and "A6" are distinctly different.
- When the original physician 1 number and physician 2 number identifiers are the same, the synthetic identifiers, MDNUM1_S and MDNUM2_S, are the same.
- When the MDNUM1 in the ambulatory surgery data and the inpatient data are the same, the synthetic identifier, MDNUM1_S is the same.
Except in those data sources where physician license numbers are supplied, it is not known whether the physician identifier MDNUM1_S refers to individual physicians or to groups. If the physician 1 numbers supplied by the data source are not restricted to license numbers, the state-specific note includes available information about reporting practices, including whether MDNUM1_S refers to individual physicians or to groups.
Beginning in the 1993 data, supplied physician 1 identifiers were checked for null characters. If null characters were found, they were replaced by blanks before the identifier was encrypted. Since this conversion was not done in prior years of HCUP data, the encrypted physician 1 identifiers from 1993 on may not match those in earlier years. However, null characters are rarely included.
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