title: Impact of interhospital transfer on outcomes for trauma patients: a systematic review.
abstract: BACKGROUND
  Evidence suggests that there may be an association between transfer status (direct admission or interhospital transfer) and outcomes in trauma patients. The purpose of this study was to systematically review the current evidence of the association between transfer status and outcomes for patients.
  
  
  METHODS
  Systematic search of Medline and EMBASE databases to identify eligible control trials or observational studies that examined the impact of transfer status on trauma patient outcomes. Data were extracted on study design, quality, participants, outcomes, and risk estimates reported. Pooled odds ratio based on data from retrieved studies was calculated using a random effect model.
  
  
  RESULTS
  Thirty-six observational studies were identified. There were no significant differences in length of stay (LOS) between transfer and direct admissions although costs were marginally higher for transferred patients, (relative increase, 1.09; 95% confidence interval, 1.08-1.09). We found no significant association between transfer status (transfer vs. direct) and in-hospital mortality (pooled odds ratio, 1.06; 95% confidence interval, 0.90-1.25); however, heterogeneity of the studies was high (I2 = 82%).
  
  
  CONCLUSIONS
  Available evidence suggests there is no difference in mortality between transfer and direct admissions. However, the significant heterogeneity across studies precludes deriving any definitive conclusions regarding the impact of interhospital transfer on mortality after major trauma. Moreover, most studies excluded patients dying at outlying hospitals, which may underestimate the association of transfer status with mortality. Prospective studies that address the limitations of the current evidence, including use of population-based trauma registries, are warranted to establish whether the process of interhospital transfer to higher level care when compared with direct admission to a trauma center negatively impacts clinical outcomes for trauma patients.
authors.affiliation: Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada. andrea.hill@sunnybrook.ca
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Hill
authors.forename: Robert A
authors.initials: RA
authors.lastname: Fowler
authors.forename: Avery B
authors.initials: AB
authors.lastname: Nathens
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D009864:Ontario; D010360:Patient Transfer / Q000458:organization & administration*; D015397:Program Evaluation; D018570:Risk Assessment; D016019:Survival Analysis; D014193:Trauma Centers; D016896:Treatment Outcome; D014947:Wounds and Injuries / Q000175:diagnosis* / Q000401:mortality* / Q000628:therapy*