But in a study of more than 9,500 patients, Majercik discovered that commonly overlooked parts of the CBC, when plugged into a risk-scoring system used by Intermountain Healthcare hospitals, can identify patients at greatest risk of dying.
The findings provide new insight into the long-term prognosis of trauma patients, which is not well understood, said Majercik, who presented them Friday at the 27th annual Scientific Session of the Eastern Association for the Surgery of Trauma in Phoenix.
Hospitals everywhere use risk scores to evaluate patients. The Intermountain Risk Score is a computer-derived composite that combines factors such as age, gender and lab results from the CBC and another blood test, the basic metabolic profile.
Majercik's colleague, Benjamin Horne, director of cardiovascular and genetic epidemiology at IMC's heart institute, had found the score useful for screening patients with heart failure or lung disease. But until now, it had not been tested on trauma patients.
"We use the CBC for other things, but we had never thought about using something so common for this," said Majercik.
She and Horne used the CBC-powered risk score to categorize 9,538 IMC trauma patients over a six-year period as high, moderate or low risk.
They found high-risk men were nearly 58 times more likely to die within a year than low-risk men. And women with a high risk were 19 times more likely to die than those with low risk.
"Two patients with the same injury might look the same, but these lab values, when we put them into this risk score, show different," said Horne. "One might be treated and released from the hospital and another might wind up in intensive care."
The risk score, said Horne, helps reveal underlying health problems that can complicate a person's recovery. In some cases, it confirms the obvious. But Majercik said there were surprises.
If the risk score uncovers an irregular red blood cell distribution in a patient, for example, that will increase his risk of dying, she said. "Typically we would only look at that for anemia. But it has proven to be a good gauge for mortality."
The researchers hope the risk score illuminates new treatment approaches.
For now, "It raises our index of suspicion," alerting doctors to be more cautious or watchful, said Majercik. "And it's helpful for setting expectations when we talk to patients and their families about their injuries."