Comparison of outcome in two series of patients with severe head injuries

A comparison is made between the outcome distributions of two Dutch series of patients with severe head injuries. Both series are taken from the same study and cover the same period (1974 to 1977). There is a large difference in survival rate between the series: 45% versus 63%. The authors present a possible method for assessing the influence of differences in initial severity of injury on outcome. It is estimated that, of the 18% difference in survival rate, 10.5% is due to differences in severity of injury on admission. The remaining 7.5% difference in survival rate is not explained, but may have been caused by unmeasured variations in the initial determination of severity of injury or by differences in effectiveness of management. The higher survival rate was achieved at the center with the more conservative management regimen. An evaluation of recent literature suggests that reports that do not find aspects of "aggressive" management beneficial are more reliable in comparing series than are those that claim improved outcome after aggressive therapy.