Background: Recent debate concerns the most appropriate definition of hypotension. Some have advocated raising the systolic blood pressure (BP) threshold to 110 mm Hg while others favor 80 mm Hg.
Hypothesis: The optimal definition of hypotension differs by age group.
Design: An analysis was performed of trauma victims 18 years and older in the National Trauma Data Bank, excluding burn injury patients and those with incomplete data.
Setting: Injured patients who were hospitalized in various trauma centers across the continental United States.
Patients: Three age groups were identified for analysis as follows: 18 to 35 years, 36 to 64 years, and 65 years and older. One hundred one multiple logistic regression analyses were performed for each population. Hypotension was sequentially defined as an emergency department systolic BP (SBP) of 50 to 150 mm Hg to see which model best predicted mortality, adjusting for demographic and injury covariates. The discriminatory power of each model was measured using the area under the receiver operating characteristic (AUROC) curve. Optimally defined hypotension was identified as the model with the highest AUROC curve.
Main outcomes measure: In-hospital mortality.
Results: A total of 902,852 patients (median age, 44 years; 66.2% men) were analyzed. Overall mortality was 4.1%. Optimal emergency department SBP cutoff values for hypotension were 85 mm Hg for patients aged 18 to 35 years, 96 mm Hg for patients aged 36 to 64 years, and 117 mm Hg for elderly patients.
Conclusions: For patients younger than 65 years, the classic definition of hypotension as an emergency department SBP less than 90 mm Hg remains optimal. With increasing involvement of elderly individuals in trauma and their peculiarity as a comorbid state, there is a need to redefine what is presently defined as a cutoff value for hypotension in elderly patients.