Newgard CD, Meier EN, Bulger EM, et al. Revisiting the “golden hour”: An evaluation of out-of-hospital time in shock and traumatic brain injury. Ann Emerg Med. Jan. 14, 2015. [Epub ahead of print.]
First described in the 1960s by R Adams Cowley, MD, a pioneer in EMS and trauma care, the idea of the “golden hour” was that patients who made it to a trauma center within 60 minutes of their injury were more likely to survive.
Moving toward evidence-based guidelines requires us to question even the most foundational of principles. Who could’ve imagined a few short years ago that oxygen and spinal immobilization could be harmful? Is the golden hour the next pillar to fall?
Methods: This study was secondary analysis of existing data from a Resuscitation Outcomes Consortium (ROC) clinical trial. The original study included 2,222 adult patients who experienced shock or traumatic brain injury (TBI). That study aimed to compare the use of normal saline, hypertonic saline and dextran.
This study included 2,017 of those same patients transported to Level 1 or 2 trauma centers over three years (2006–2009). The researchers created two “cohorts.” The shock cohort included patients (n=778) with a systolic blood pressure (SBP) < 70 mmHg or the combination of SBP 71–90 mmHg with a pulse > 108. The TBI cohort (n=1,239) included adult patients with a Glasgow Coma Scale ≤ 8.
Patients were excluded from the study if they were ≥ 4 hours from the time of injury or if they received greater than 2 L of crystalloid.
The researchers also excluded children, patients who were pregnant, those who were incarcerated or in the custody of police, hypothermic patients and those with less common mechanisms of injury (e.g., hanging, drowning, penetrating head trauma).
The goal of the study was to compare survival for patients treated within the golden hour to those with > 60 minutes of prehospital time. Survival was defined as 28-day mortality for the shock cohort, and good Glasgow Outcome Scale–Extended (GOSE) for the TBI cohort.
Multivariate logistic regression analyses were used to test which variables might influence survival: age, gender, mechanism of injury, vital signs, mode of transport and regional location.
Results: The median out-of-hospital time for all patients was 44 minutes, which was similar when broken down by cohort. Among the 778 patients in the shock cohort, 203 (26%) died within 28 days of their injury. Among the 1,239 patients in the TBI cohort, 652 (53%) had a GOSE score ≤ 4 at six months and 304 (25%) died within 28 days. Total out-of-hospital time wasn’t associated with 28-day mortality for patients in either cohort or with neurologic outcome at six months for patients in the TBI cohort.
Further subgroup analysis found that patients in the shock cohort who required early critical interventions (n=95), which was defined as packed red blood cell transfusion ≥ 6 units, major non-orthopedic surgical procedures, interventional radiology procedures or death, had a higher 28-day mortality when compared to those who didn’t require early critical intervention (OR 2.37; 95% CI=1.05–5.37). The same didn’t hold true for patients in the TBI cohort.
Limitations: Secondary analyses of data collected for a different purpose can be fraught with complications. Out-of-hospital time in this study was measured from the receipt of the 9-1-1 call, which isn’t consistent with previous studies. Potential “ramping” (delays between arrival at the ED and hospital-based definitive care) time was also not accounted for. The study authors used arbitrary inclusion and exclusion criteria for particular types and severity of traumatic events.
Discussion: Less than 5% of all patients included in this study experienced higher mortality when 9-1-1 call time to ED was greater than 60 minutes. The patients in the higher mortality group had critical injuries with major hemodynamic instability.
Due to the limitations of the study, we don’t accurately know if the golden hour was appropriately challenged.
Conclusion: Since the 1960s, prehospital trauma care has grown by leaps and bounds thanks to years of research in both the military and civilian realms. We know that patients definitely benefit from expedited care both on scene and in the hospital. As with all interventions, risks of rapid lights-and-siren transports must be weighed against the high rate of crashes (9% of all EMS provider injuries reported in 2012 were related to transportation, according to the Centers for Disease Control and Prevention). More research is needed to determine if 60 minutes is truly a golden hour.
What we already know: Major trauma patients need rapid, safe transportation to appropriate facilities for definitive care.
What this study adds: Emphasis on the need to do rigorous prospective research on the efficacy of time intervals as performance measures.