NAMCS and NHAMCS Public Use Data File Updates

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Visit the National Ambulatory Medical Care Survey website at https://www.cdc.gov/nchs/namcs/ and the National Hospital Ambulatory Medical Care Survey at https://www.cdc.gov/nchs/nhamcs/ for more information about these surveys.

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This page contains a list of updates that have been made to the NAMCS and NHAMCS public-use micro-data files and since their initial release dates. Data users can check here for any revisions that have been made to ensure that they are using the most accurate version of the files. For changes to the public-use micro-data file documentation (including general documentation and SAS, Stata, and SPSS programming code), please see Documentation Updates. Updates are arranged by survey and year.

NAMCS

  • 2016 NAMCS Public Use Data File
    9/10/19 – A problem was found with the checkbox for CHF (Congestive Heart Failure) in the item: “Regardless of the diagnoses written above, does the patient now have:”.  This checkbox is typically edited to ensure that any diagnoses of CHF reported in the survey items  DIAG1-DIAG5 (Diagnosis #1 – Diagnosis #5) are also reflected in the CHF check box.  It was recently discovered that the ICD-10-CM codes I50.1-I50.9 (Heart Failure) were not included in the edit.  In all, 28 records with a diagnosis of Heart Failure reported in DIAG1-DIAG5 should have had the CHF checkbox checked but did not.  These records represent 1,883,000 weighted visits.  If they had been included, the estimated number of visits where CHF was checked would increase from 15,169,000 to 17,052,000, and the percentage of all visits with CHF checked would increase from 1.7% to 1.9%.  The public use data file is not being rereleased, but data users can easily compensate for this problem by adding any visits with a diagnosis in the range of I50.1-I50.9 to the CHF checkbox. Data users should also note that changes to CHF will affect two other variables: NOCHRON (patient has none of the chronic conditions listed) and TOTCHRON (total number of chronic conditions reported). For each of the 28 records cited above, if no other chronic conditions were reported, the NOCHRON value should be changed from 1 (“none” checked) to 0 (“none” not checked).  Also, the TOTCHRON value for each of the 28 records will need to be increased by 1.
  • 2015 NAMCS Public Use Data File
    9/7/17 – The 2015 NAMCS Public Use Data File was updated to change an invalid (corrupted) diagnosis code on the DIAG2 and DIAG2R variables for one record and the DIAG4 and DIAG4R variables for another record. The pre-made Stata dataset was also corrected.
  • 2014 NAMCS Public Use Data File
    4/3/19 – The 2014 NAMCS Public Use Data File was updated to correct problems found in the ‘new’ or ‘continued’ status of reported medications.  Due to a data processing issue, these items were often set to missing instead of to a new or continued status.  The revision affects the variables NCMED1-NCMED30, NUMNEW and NUMCONT.  Pre-made SAS, SPSS, and Stata datasets have also been recreated.
  • 2011 NAMCS Public Use Data File
    12/16/15 – The 2011 NAMCS Public Use Data File was updated to change the CSTRATM value for one physician to fix a singleton (occurrence of a single respondent within a sampling stratum or cluster in areas not selected with certainty) that was found following the initial file release. Variance estimation results should be very similar for both the original and the revised files. This fix mainly benefits data users whose software does not correct for singletons.
  • 2002 NAMCS File (affects some SUDAAN users only)
    9/29/04 - The 2002 NAMCS public use file was modified slightly to resolve a problem found when running SUDAAN version 8.0.2 and higher. This problem only appears when using the WOR (without replacement) design option with multi-level design variables and may cause the program to abort. For those using the SUDAAN WR (with replacement) option or other analytic software packages using an ultimate cluster model for variance estimation (for example, SAS, Stata, and SPSS), there should be no problem using the original version of the 2002 NAMCS public use file, so you do not need to replace your file with this new release.
 

NHAMCS

  • 2019 NHAMCS Emergency Department Public Use Data File
    2/3/22 – A new version of the public use file was released which includes the ED weight variable (EDWT) only on the first record for each hospital (based on the HOSPCODE variable). The initial file release included this variable on all ED records. It is easier to produce facility-level estimates when the EDWT variable is present on only one record for each ED, and that is the way the file has traditionally been released. To calculate facility-level estimates correctly, it is recommended that the revised version of the file be downloaded. Visit-level estimates are unaffected.
  • 2016 NHAMCS Emergency Department Public Use Data File and Documentation
    9/10/19 – A problem was found with the checkbox for CHF (Congestive Heart Failure) in the item: “Regardless of the diagnoses written above, does the patient now have:”.  This checkbox is typically edited to ensure that any diagnoses of CHF reported in the survey items DIAG1-DIAG5 (Diagnosis #1 – Diagnosis #5) are also reflected in the CHF check box.  It was recently discovered that the ICD-10-CM codes I50.1-I50.9 (Heart failure) were not included in the edit.  In all, 45 records with a diagnosis of Heart Failure reported in DIAG1-DIAG5 should have had the CHF checkbox checked but did not.  They represent 359,000 weighted visits.  If they had been included, the estimated number of visits where CHF was checked would increase from 4,111,000 to 4,470,000, and the percentage of all visits with CHF checked would increase from 2.8% to 3.1%.  The public use data file is not being rereleased, but data users can easily compensate for this problem by adding any visits with a diagnosis in the range of I50.1-I50.9 to the CHF checkbox. Data users should also note that changes to CHF will affect two other variables: NOCHRON (patient has none of the chronic conditions listed) and TOTCHRON (total number of chronic conditions reported). For each of the 45 records cited above, if no other chronic conditions were reported, the NOCHRON value should be changed from 1 (“none” checked) to 0 (“none” not checked).  Also, the TOTCHRON value for each of the 45 records will need to be increased by 1.
  • 2016 NHAMCS Emergency Department Public Use Data File and Documentation
    1/25/19 – The 2016 NHAMCS Emergency Department Public Use File has been updated to modify the formatting for various diagnosis codes (DIAG1-DIAG5; HDDIAG1-HDDIAG6). The earlier version contained a number of International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes which were incorrectly assigned to a broader category within the same diagnosis group during data processing.  For example, ICD-10-CM code N39.0, Urinary tract infection, site not specified, appears on the original release as N39-, Other disorders of the urinary system.  This aggregation to higher categories resulted in a loss of detail that has been restored in the new release. The new zipped files are dated 1/25/2019; they include the ASCII data set and the pre-made SAS, Stata, and SPSS data sets.
  • 2009 NHAMCS Emergency Department Public Use Data File and Documentation
    9/20/11 – The 2009 NHAMCS Emergency Department Public Use File has been updated to include a change to the visit disposition variable ADMITHOS (admit to this hospital). Original file data are correct, but it was discovered that some researchers were not aware that the disposition OBSHOS (admitted to observation unit, then hospitalized) should also be used to capture visits resulting in hospital admission. To simplify matters, we have edited ADMITHOS to Yes whenever OBSHOS is Yes. Therefore, ADMITHOS will now reflect all visits resulting in hospital admission, either directly or through the observation unit. A note regarding this change has also been added to the Public Use Data File Documentation. Researchers using the original version of the file who are interested in hospital admissions need only select records where ADMITHOS is Yesor OBSHOS is Yes to capture all hospital admissions.
  • 2004 NHAMCS Emergency Department File
    8/4/06 - A slightly revised version of the 2004 NHAMCS Emergency Department file was uploaded to the ftp server. This file incorporates modifications to the edit process for the internal variables used to calculate WAITTIME (waiting time to see a physician) and LOV (length of visit). The revised WAITTIME and LOV are only minimally different than the first release, but have been made available in the interest of consistency with NCHS reports, the revised edit procedures, andfuture years of data which use those procedures.
  • 2002 NHAMCS Emergency Department File
    12/10/04 - We made revisions to two data items on the NHAMCS-Emergency Department public use file for 2002. These are ADRG2CL1 (1st NDC class for 2nd drug causing an adverse drug event) and DRG3ING5 (5th ingredient for 3rd medication provided or prescribed). Revisions were also made to one item on the NHAMCS-Outpatient Department file, EXAMWI2 (2nd write-in examination).
  • 2002 NAMCS File (affects some SUDAAN users only)
    9/29/04 - The 2002 NAMCS public use file was modified slightly to resolve a problem found when running SUDAAN version 8.0.2 and higher. This problem only appears when using the WOR (without replacement) design option with multi-level design variables and may cause the program to abort. For those using the SUDAAN WR (with replacement) option or other analytic software packages using an ultimate cluster model for variance estimation (for example, SAS, Stata, and SPSS), there should be no problem using the original version of the 2002 NAMCS public use file, so you do not need to replace your file with this new release.