Scoring Systems Don't Predict Vascular Trauma Deaths

August 2010

By Sherry Boschert
Elsevier Global Medical News 

SCOTTSDALE, ARIZ. -- Two common scoring systems used to estimate the risk of dying from trauma underestimated the mortality risk in patients with vascular trauma in a review of 100 patients.

The study is the first to compare outcomes in similar patients with vascular or nonvascular trauma injuries and assess the usefulness of injury severity scoring systems for predicting mortality after vascular trauma. The scoring systems were developed for the general trauma population and have not been validated in patients with vascular trauma, Dr. Shang A. Loh said at the annual meeting of the Society for Clinical Vascular Surgery.

He and his associates analyzed data on 50 patients with vascular trauma and 50 with nonvascular trauma who were matched by Injury Severity Score (ISS). The two groups were similar in age, sex, mechanism of injury, and other characteristics.

The primary outcome of the study showed a trend toward higher mortality in patients with vascular trauma (24%) than in those with nonvascular trauma (12%), but this did not reach statistical significance, reported Dr. Loh of New York University Medical Center.

Secondary analyses found differences between groups when predicting fatalities using the Revised Trauma Score (RTS) or Acute Physiology and Chronic Health II (APACHE II) scores.

They analyzed a subset of patients whose ISS, RTS, or APACHE II scores would suggest a good chance of survival. Among those with an ISS less than 24, 11% of vascular trauma patients and 3% with nonvascular trauma died, a trend that again did not reach statistical significance. Among those with an RTS greater than 5, however, the 26% mortality rate in those with vascular trauma was significantly higher than was the 2% rate in patients with nonvascular trauma. Fatality rates for patients with APACHE II scores less than 14 were 18% in those with vascular trauma and 0% with nonvascular trauma, a significant difference.

"Almost all of the mortality was in the vascular trauma group," Dr. Loh noted. "This demonstrates that the presence of vascular trauma leads to increased mortality in those patients who are not thought to be critically injured based on these scoring systems."

The investigators then averaged the RTS scores for patients who died of vascular or nonvascular trauma. They were surprised to find a significantly more "favorable" RTS score (6) among vascular trauma fatalities, compared with nonvascular trauma fatalities (4), "demonstrating that the RTS fails to reflect the severity of vascular trauma," he said.

When the researchers averaged the APACHE II scores among patients who died, they found a more favorable average score (17) among vascular trauma fatalities than among nonvascular trauma fatalities (26). The better APACHE II score in the vascular trauma patients erroneously would suggest a lower risk for mortality, "causing one to underappreciate the actual severity involved," Dr. Loh said.

A similar trend was seen in average ISS scores for patients who died of vascular or nonvascular trauma, but this did not reach statistical significance. Average ISS scores were 38 for vascular fatalities and 47 for nonvascular fatalities.

He speculated about why the scoring systems don't reflect risks from vascular trauma. Often the RTS or another scoring system is used immediately as a patient enters the trauma bay, but clinical manifestations of vascular injury might not appear right away, especially in young, healthy patients, Dr. Loh said.

The investigators reported no conflicts of interest.

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