The complete blood count, or CBC, is an inexpensive test that measures a person's red blood cells, white blood cells and platelets. Harvard researchers say those numbers may also provide information about a person's life expectancy.
"By measuring the diameter of the red blood cells, they can predict longevity or, the inverse of that, predict mortality," said Dr. Lawrence O'Connor, a cardiologist with Glendale Memorial Hospital.
O'Connor says researchers developed a formula to measure longevity using a patient's red blood cells. They compared and tracked 17,000 people in 26 countries for five years. Individuals in the study with "low" test scores were twice as likely to live longer than those with the highest scores. But whether or not this information will help doctors treat patients remains to be seen.
"Well we know what the measurement is. We know that the measure is easy to get, and we need to find a place for it in clinical practice," said O'Connor.
Study authors believe the CBC test can be an effective tool in managing heart patients. O'Connor says for some, a longevity score might offer patients a positive incentive.
"I think if you could show somebody a number and it lit a fire under them to take care of their ongoing risk factors, then that would be a big thing," said O'Connor.
Experts agree that living a long, healthy life isn't about test scores, it's about changing behaviors.
An expert points out that one of the beauties of this "risk score" is that it already uses something that's clinically familiar to doctors. The other positive is that since the CBC is a test most patients already receive, there's no additional cost.