Alternative to the Science Citation Index impact factor as an assessment of emergency medicine's scientific contributions.

STUDY OBJECTIVE: The Science Citation Index "impact factor" is the only available quantitative estimate of a journal's scientific contributions. However, the derivation of this factor contains an intrinsic bias that underestimates the impact of emergency medicine journals. We wished to test the hypothesis that use of an alternative criterion standard would provide an improved profile of the scientific contributions of emergency medicine journals relative to those of other specialties. METHODS: We used an observational, longitudinal, comparative design in which all Index Medicus citations from Advanced Cardiac Life Support (ACLS) publications were aggregated by journal and then stratified by specialty. Proportions and proportionate trends, relative to total citations, were reported by specialty, facilitating comparison of emergency medicine with other disciplines. RESULTS: Among all eight ACLS publications (1974-1994) 4,062 citations met the inclusion criteria. Emergency medicine journals were referenced in 16% of eligible citations (99% confidence interval [CI], 14% to 17%), a figure exceeded only by internal medicine and cardiology journals. Emergency medicine was the only discipline to show a significant proportionate increase in contributions over the 20-year study period (P < .001 by chi 2 for linear trend analysis). CONCLUSION: Contrary to the implications of a low impact factor, an analysis of journal citations in ACLS publications over two decades suggests that emergency medicine has made significant contributions to a broad and important area of scientific inquiry.

Evidence of methodologic bias in the derivation of the Science Citation Index impact factor.

STUDY OBJECTIVE: The "impact factor" published in Science Citation Index (SCI) is widely used in the scientific community to measure the relative importance of a medical journal. In contrast to all other indicators of academic growth in emergency medicine, impact factors for emergency medicine journals have remained low and unchanged since the inception of the specialty. We wished to investigate this incongruity. METHODS: We examined the methodology used to derive the SCI's journal impact factor. RESULTS: The impact factor for journals is defined mathematically as the number of times a journal is cited over a period of time (the numerator) divided by the number of articles published by that journal during the same period (the denominator). Citation counts are derived from examination of all references contained in a subset of journals known as "source" journals. No emergency medicine journals are included in this group. The only source of citations for emergency medicine journals is from journals outside of emergency medicine. This produces small numerators with relatively constant denominators, leading to low impact factors. CONCLUSION: The apparent failure of emergency medicine journals, as measured by the SCI impact factor, to keep pace with other indicators of academic development of the field is at least in part attributable to a methodologic bias inherent in the derivation of this factor.

Isolated intrathoracic injury with air bag use.

The restrained (air bag and seatbelt) driver of a vehicle involved in a high-speed motor-vehicle accident sustained a tear of the thoracic aorta with no signs of external injury. Air bag deployment may mask significant internal injury, and a high index of suspicion is warranted in such situations.