372 Derivation of a Clinical Decision Instrument to Identify Adults in a Community Setting With Mild Traumatic Intracranial Hemorrhage at Low Risk for Requiring Critical Care Intervention

Abstract

Adults presenting to the ED with mild traumatic intracranial hemorrhage (tICH) are commonly admitted to the intensive care unit (ICU), although critical care interventions are often unnecessary. In prior research, we found that a clinical decision instrument (CDI) derived at an academic Level I trauma center to identify adults at low risk for critical care interventions performed poorly in a community setting, likely because of substantial differences in patient case-mix. We sought to derive a more generalizable CDI among patients of a large community-based integrated health care delivery system. This retrospective cohort study included non-anticoagulated adults (≥18 years of age) with mild tICH, defined as GCS score ≥13, across 21 community EDs from 01/2012 to 12/2013. No study facility carried a Level I trauma center designation, and only one carried a Level II designation. The primary outcome of at least one critical care intervention within 48 hours of ED arrival included intubation, neurosurgical intervention, vasopressor or inotrope use, invasive monitoring, or cardiopulmonary resuscitation. Using logistic regression with single independent variables, we identified potential predictors of the outcome, developed a 6-variable predictive logistic regression model, and created a simplified CDI to identify low-risk patients based on predicted probabilities from the model. We examined the prevalence of patients designated low-risk by both CDIs and compared performance metrics. We calculated sensitivity and specificity with Clopper-Pearson, positive and negative predictive values with standard logit, and c-statistics with Wald confidence interval (CI) estimates. Our cohort included 929 patients with mean age of 73.3 (SD 17.0) years; 50% were female, and 82% were injured by a ground-level fall. Of these, 110 (11.8%) received at least one critical care intervention, 100 of whom received a neurosurgical operation, mannitol or hypertonic saline. Patients identified as low risk had none of the following: time from trauma to ED >7 days, ED admitting GCS <15, lowest ED systolic blood pressure >140 mmHg, CT evidence of skull fracture, mass effect, or midline shift >5 mm. The new CDI designated nearly three times as many patients as low-risk than the academic-based CDI with similar sensitivity and significantly higher specificity (see Table). We derived a CDI to identify patients with mild tICH at low risk for requiring ICU-level care in this community setting. The community-based instrument was equally sensitive as its academic counterpart, but outperformed it with a greater specificity and positive predictive value. This lower rate of false positives may increase its ultimate clinical utility. Continued model development may further improve specificity, and a prospective validation study will be needed prior to clinical implementation.