Women have lower complication and mortality rates after traumatic injuries compared with men who suffer similar injuries, a new study suggests.

Using the National Trauma Data Bank, researchers analyzed data from 681,730 adult patients—432,085 men and 248,745 women—who had a hospital stay of at least three days. Women had a lower prevalence of all complications studied, except for urinary tract infection, according to a report in Surgery (2009;146:308-315).

They also had a 21% lower risk of death compared with men, after adjusting for potential confounders, including age, race, mechanism, type, and intent of injury, insurance status, injury severity, and the presence or absence of complications.

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The proportion of subjects who experienced any of five life-threatening complications—defined as those associated with the highest mortality rates—was 3.04% in women compared with 5.09% in men, a significant difference between the genders. In addition to ARF, the other life-threatening complications were acute respiratory distress syndrome, pneumonia, pulmonary embolism, and intra-abdominal abscess.

Interestingly, though women are less likely to develop most complications then men, if women do develop life threatening complications they are more likely to die. For example, development of ARF was associated with an 8.7 times increased risk of death in females and a nearly five times increased risk of death in males. This difference translated into a 75% increased risk of death in women who developed complications, when compared to with men who didn’t have any complications. On the other hand men who developed complications only had a 48% increased risk of death when compared to the reference group of men who did not have any complications.

“This study demonstrates that women have a survival advantage over men with equivalent injuries,” the authors wrote. “It also suggests that differences in the occurrence in life-threatening complications may play a prominent role in this gender disparity.

“This large study,” the authors continued, “adds to the multitude of literature that provides significant experimental and clinical evidence that women have a survival advantage over men after traumatic injury and are less susceptible to developing multiple organ failure, infections, and life-threatening complications.”

Commenting on the implications of the study, lead investigator Adil Haider, MD, MPH, Assistant Professor of Surgery and Co-Director of the Center for Surgery Trials and Outcomes Research at Johns Hopkins School of Medicine in Baltimore, observed that the first step is elucidate why women are at lower risk for complications following traumatic injury.

“In the longer run,” he said, “studies like these may be the basis for innovative therapies designed to take advantage of this gender dimorphism. For example, if we determine that male sex hormones worsen the body’s ability to fight shock and sepsis, we could treat this with testosterone blockers for a short period of time, just until they get out of shock.”

Previous studies looking at the effect of gender on outcomes after non-penetrating trauma and critical illness have had conflicting results. For example, a prospective study published last year by Jason Sperry, MD, and colleagues (Crit Care Med. 2008;36:1838-1845) showed that severe complications are much more likely to develop in men than women. But a retrospective study led by David Hoyt, MD, found that female gender is not protective against complications or death (J Trauma. 2002;53:436-441).

Dr. Hoyt, Professor and Chairperson of Surgery at the University of California in Irvine, said the contradictory findings from the various studies make these latest results difficult to interpret. He observed, however, that there is significant support for a protective effect of estrogen following trauma.