Evidence-based assessment of well-established interventions: The parachute and the epidural hematoma

BACKGROUND: The methods of evidence-based medicine are a relatively recent development in the understanding of clinical practice. They are criticized as not providing support for interventions long held to be highly effective based on experience that predated the availability of evidence-based analysis. OBJECTIVE: To determine if the methods of evidence-based medicine can be successfully applied to interventions established before those methods were developed. METHODS: Systematic review of English language literature on the natural history and treated prognosis of acute epidural hematoma and analysis of existing data on mortality associated with parachute use. DATA SOURCES: Sources of data included Medline, Old Medline, Science Citation Index, British and US Parachute Associations, and Federal Aviation Administration and National Transportation Safety Board databases (both of the United States). Also included were national databases reporting mortality and total number of parachute uses. RESULTS: The estimated mortality of falling from an airplane with an ineffective parachute is 74% (69-79). Mortality associated with effective parachute deployment is between 0.0011% and 0.0017%. For acute epidural hematoma, estimated mortality is 98.54% (95.1-99.9) without treatment and 12.9% (10.5-15.3) with treatment. The number needed to treat to prevent 1 death for the parachute is estimated to be 1.35 (1.27-1.45) and for epidural hematoma 1.17 (1.13-1.22) (95% binomial confidence intervals in parentheses). CONCLUSION: The methods of evidence-based medicine are robust and can deal with interventions of great face validity and those considered well established before such methods were well developed. We propose initial criteria for evaluating the quality of evidence supporting long-established interventions.