Can mechanism of injury improve trauma diversion? A retrospective cross-sectional study

Objective: The objective of this study was to determine the impact of adding selected mechanism of injury (MOI) to the existing trauma diversion criteria adopted in Hong Kong. Method: This is a cross-sectional study based on the trauma registry of New Territory West Cluster (NTWC) of Hospital Authority from January 2017 to December 2019. All adult patients aged 18 years or above were recruited if their injury occurred in the catchment area of Pok Oi Hospital (POH) or Tin Shui Wai Hospital (TSWH). Performance of the protocol before and after MOI criteria being added in terms of over-diversion and under-diversion rate was determined. Model discrimination was evaluated by plotting the receiver operating characteristic curve, and the area under the curve was compared before and after MOI criteria added. Net reclassification improvement and integrated discrimination improvement indices were evaluated. Result: A total of 502 patients were included for analysis. Before MOI criteria were added, the over-diversion rate and under-diversion rate were 31.1% and 54.7%, respectively. After MOI criteria were added, the over-diversion rate and under-diversion rate were 33.1% and 34.3%, respectively. The receiver operating characteristic curve of current primary trauma diversion (PTD) criteria had an area under the curve of 66.9% (95% confidence interval: 63%–71%). After adding MOI criteria, the new receiver operating characteristic curve yielded an area under the curve of 73.7% (95% confidence interval: 70%–78%), which is significantly better (p < 0.001). Net reclassification improvement and integrated discrimination improvement indices indicated that including MOI criteria would improve the model prediction. Conclusion: Adding mechanism of injury can improve trauma diversion protocol performance.