Articles: emergency-medicine.
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In the analysis of a clinical trial an investigator may fail to discern a statistically significant difference in outcome between control and experimental groups, when in fact one exists. Failure to demonstrate such a difference when it actually exists is known as "type II" error, and its probability of occurring is termed "beta." The purpose of our study was to determine the distribution of beta errors in negative trials in the Journal of the American College of Emergency Physicians (JACEP) (1972-1979) and Annals of Emergency Medicine (1980-1984). All negative comparative clinical trials appearing in JACEP and Annals from volume 1 (1972) to volume 13 (1984) were surveyed and were eligible for inclusion in the study. ⋯ Only one of the trials (7.1%) addressed the issues of beta errors and sample size determination. In the remaining 13 negative trials, the calculated beta error ranged from .60 to .97. For the endpoints analyzed, a sample size of up to 450 times larger than that used would have been required to detect a clinically important difference.(ABSTRACT TRUNCATED AT 250 WORDS)
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One hundred ten consecutive trauma patients transported directly from the scene of injury by a hospital-based helicopter emergency medical service were reviewed. These patients were injured in the rural areas of central and northeastern Pennsylvania and were transported to a level I trauma center. The medical flight team consisted of an emergency physician and a registered nurse. ⋯ The average scene time was 33.6 minutes for transported patients. Sixteen patients required extrication after the arrival of the flight crew and had significantly prolonged scene times averaging 61.8 minutes (P less than .001). Patient entrapment was the most important contributing factor in on-scene ground time.