Medical experts agree with decision to sit Steelers safety Clark
John Kark has no argument with Steelers safety Ryan Clark skipping the Broncos in Sunday's AFC wild-card playoff game in Denver.
"Probably if I were him, I wouldn't play," said Kark, a doctor and associate professor in the hematology-oncology department at Howard University Hospital. "He had complications before. He had a substantial response to exercise and altitude. He might have other risk factors that other people don't have."
Clark does not have a disease. He has a "variant" known as sickle cell trait. "A pretty safe variant," said Kark, who has studied the subject in depth.
However, he added, "There are circumstances where you could have problems."
Among them is exertion in high altitude. Denver is accurately named the "Mile High City." Even its stadium shares the nickname. After a Steelers-Broncos game in October 2007, Clark experienced severe pain, followed by removal of his spleen and gallbladder. He lost 30 pounds and missed the rest of the season. He did not play in a 2009 Monday Night Football game and a 2010 preseason game in Denver.
The cause was the sickle cell trait, a genetic blood disorder present in about 8 percent of African-Americans and less than 1 percent of white Americans. Kark, who has done extensive research on members of the military with the trait, said the trait alone poses little or no problem for the approximately three million people in the U.S. who have it.
But altitude, intense activity in hot weather and dehydration can exacerbate the sickle-cell trait and cause symptoms similar to sickle cell disease, which often has dire effects.
Sickle cell trait is the inheritance of one gene for sickle hemoglobin and one for normal hemoglobin. For those who have it, decreased amounts of oxygen in high-altitude locations cause a greater risk for their red blood cells "sickling" - literally forming into the shape of a sickle and preventing the delivery of additional oxygen to organs and tissues.
Even with Clark's spleen removed, other organs might have been affected.
"It would seem if somebody had a problem and it was altitude related, there is the possibility something like that could happen again," said Dr. Oswaldo Castro, professor emeritus of the Howard medical school and former director of the university's Center for Sickle Cell disease.
The potential consequences are hard to specify. But the prevailing attitude toward Clark is "Why take chances?" Steelers coach Mike Tomlin said as much when he noted that the team would "err on the side of caution."
"We're talking about a pretty unlikely event, but the question is, how seriously should we take it?," said Kark. "If someone's life is at stake, you take it pretty seriously."
Frank Ferrone, a physics professor at Drexel University who has researched the subject, said the risk of death would have been small, "but people in this situation have died. There are a number of cases in which people who have gone through extreme exertion have died from this."
Although there is no documented connection between any American pro athlete's death and sickle cell trait complications, at least 17 deaths of young athletes in the U.S., including nine college athletes in a seven-year span, have been attributed since 2000.
Every newborn in the U.S. is now tested for sickle cell trait. The NFL tests new players for sickle cell trait at its annual combine. The NCAA in August 2010 began testing in Division I, but athletes can refuse by showing proof of a previous test or signing a release to decline. Legislation is pending to expand testing to Divisions II and III. The NCAA website lists several links to sickle trait-related topics.
But despite research and increased awareness, unanswered questions remain. "There's a lot of gray," Kark said. "There are a lot of things that are unknown."