Emergency Department Visit Data

Data Source

NHAMCS, Emergency Department – Injury Summary

Medical information about patient visits includes up to three reasons for the visit as expressed by the patient, up to three physician diagnoses, up to three external causes of injury (if visit was for an injury), checklists of diagnostic/screening services and procedures ordered or provided, and up to six medications that were either ordered, supplied, administered, or continued at the visit. Diagnoses are coded using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM).

The data collection instrument for this survey is a one-page questionnaire called the Patient Record Form.

Emergency department visits for injury are broadly defined in the NCHS publications of the Ambulatory Care Statistics Branch in order to reflect the burden of injury in the ED setting. However, injury visits are defined more narrowly in the Injury Chartbook [PDF – 66 KB]. The decision to narrow the scope was made by the Injury Team of the Special Projects Branch in the NCHS Office of Analysis and Epidemiology in an effort to make the definition of injury in an emergency department setting more comparable to what States are able to calculate see NCHS Health E-Stat. The more narrowly defined injury visit is an incidence-based rather than a burden-based measure. Thus, the definition of an injury visit includes initial visits for which there is either a first- listed injury diagnosis, or a valid external cause of injury code listed describing the circumstances of the injury event. Visits with a first-listed diagnosis describing a complication or adverse effect of medical care were excluded regardless of the external cause code. The relevant ICD-9-CM codes for injury diagnoses and for external causes of injury can be found in tables 2 and 3 of the report, and in the Tools and Framework section of the Injury Data and Resources website.



Public-use Data

Public-use microdata files may be downloaded in ASCII format. These files generally require the use of statistical software such as SAS, SPSS, or Stata to read the data. Downloadable data files and documentation are available for all survey years (1992-present). Downloadable files for 1993-present include masked design variables needed for variance estimation software as well as SAS input, label, and format statements. Stata and SPSS program statements are available for data years 2002-present.

We recommend basing ED rates on the U.S. civilian population. Population data for estimated U.S. civilian population by single year of age and sex based on Census 2000 may be downloaded in SAS and Excel format for the years 1992-present.

Tools and Frameworks

Programs and Statements for Injury Data Analysis

  • SAS statements for assigning external cause of injury codes to mechanism and intent of injury based on the ICD-9-CM external cause of injury matrix in NHAMCS-ED.
  • SAS statements for selecting 1st listed injury diagnosis and 1st listed E-code for defining an injury record in NHAMCS-ED
  • STATA program for selecting 1st listed injury diagnosis and 1st listed E-code for defining an injury record in NHAMCS-ED.
  • Sample SAS and SUDAAN codes and documentation for variance estimation of complete NHAMCS-ED data.
  • Example of a SAS Program for Obtaining Frequencies of Injury Visit in NHAMCS-ED:
    Sample SAS and SUDAAN programs that create weighted frequency counts for injury visit by age and gender and export to Excel file. You will need to modify the program to get the weighted frequencies for desired subpopulation, year, and age groups.

Links to Other Emergency Department Data