title: Therapeutic intervention scoring as a measure of performance in a helicopter emergency medical services program.
abstract: Helicopter emergency medical services (HEMS), which are both expensive and resource intensive, lack objective measures for system evaluation. We computed the Therapeutic Intervention Scoring System (TISS) score for all patients during six consecutive months of service in a HEMS program to assess the value of this score for measuring the performance of the program. The TISS assigns values ranging from 1 to 4 for 57 medical and surgical interventions to measure the intensity of care during a 24-hour period. The TISS was recorded for 203 patients beginning at the time HEMS transport was requested. These flights also were classified as appropriate or inappropriate, given the information available, when HEMS care was initiated and days later when diagnostic evaluation was complete. Classification was done on the basis of whether the following criteria (potentially) ensure patient survival or improve outcome: speed of transport, presence of a medically skilled flight team, or the helicopter's ability to overcome hostile environmental conditions. The mean TISS score for all patients was 21.7. One hundred thirty-two of 203 flights (65%) were thought to be medically necessary, both at the time HEMS was requested and later (mean TISS, 28.1; analysis of variance, P less than .001). Thirty-four flights (17%) were thought to be appropriate using the information available at flight time, but not after the diagnostic workup was completed (mean TISS, 10.0). Thirty-six patients (18%) did not appear to require helicopter transport at any time, and had a mean TISS of 9.0. We conclude that TISS is a useful, objective measure of the performance of a HEMS program, and it should be tested in other HEMS programs.
mesh_terms: D000328:Adult; D000401:Aircraft; D002648:Child; D002983:Clinical Competence; D004632:Emergency Medical Services / Q000592:standards*; D005069:Evaluation Studies as Topic; D006801:Humans; D014187:Transportation of Patients / Q000592:standards*; D014481:United States