Encounter

Medical encounter data was received from the Defense Medical Surveillance System (DMSS) database run by the Armed Forces Health Surveillance Division (AFHSD). Medical encounters provided include inpatient and outpatient medical records, as well Theater Medical Data Store (TMDS) records. The inpatient records cover hospital stays; outpatient records cover other doctor visits not involving a stay in a hospital; TMDS records cover data collected from medical treatment in a military environment (i.e., at a deployment location, on a military ship, etc.). The data includes 615,107 inpatient records from 261,285 people; 117,766,794 outpatient records from 749,689 people; and 845,436 TMDS records from 174,498 people. Inpatient records were collected from 1990 through 2023; outpatient records were collected from 1996 through 2023; TMDS records were collected from 2008 through 2023.

All three types of medical encounter data included a list of ICD-9-CM or ICD-10-CM diagnosis codes. Each individual encounter record includes all diagnosis codes recorded at that doctor visit or hospital visit. The inpatient data also includes a list of ICD-9-CM or ICD-10-CM procedure codes for procedures performed during that visit. The outpatient data includes a list of Current Procedural Terminology (CPT) codes for procedures at that visit and a Medical Expense and Performance Reporting System (MEPRS) code for that visit.

The availability of medical encounter records differs based on whether the service member is active duty, reserved, or is no longer in military service. After separation, encounters are only received for individuals who remain within the Tricare system (e.g., retired members' Tricare For Life). The table below provides an overview of what percentage of individuals have a medical claim in a particular year, based on their military service status.

Organization

The medical encounter data have been processed into three files: cancers, non-cancer conditions, and medical procedures. Cancers diagnoses for the Military Aviators Cancer Study (MACS) combine data collected from the medical encounter data as well as records from cancer registries (Department of Defense Cancer Registry and Veteran's Affairs Central Cancer Registry). See the Cancer page for more information.

For cancers and non-cancer conditions, one diagnosis may be mentioned in many medical encounter records. When multiple records are present, those records are processed into summary information so that each instance of a cancer or condition has a single summary record. For the procedure data, it is assumed that procedures recorded multiple times represent multiple instances of those procedures. As such, records are not combined for those data.

Summary

• Data collected for 893,941 service members, of which 769,977 (86%) have at least 1 encounter record
• Number of records:
  • Inpatient: 615,107 claims for 261,285 people
  • Outpatient: 117,766,794 claims for 749,689 people
  • TMDS: 845,436 claims for 174,498 people
• Medical encounters were collected:
  • Inpatient: 1990-2023
  • Outpatient: 1996-2023
  • TMDS: 2008-2023

Numbers based on the 156,000 service members included in data received as of September 2024.

Variables

• ICD-9/ICD-10-CM diagnosis codes (inpatient, outpatient, and TMDS)
• ICD-9/ICD-10-CM (inpatient) or CPT (outpatient) procedure codes
• MEPRS codes (outpatient)