No, a New Blood Test Is Not Going to Help Football Sideline Testing

The NFL's concussion protocols have come under scrutiny again this season, with the treatment of players drawing criticism from fans and, in the case of Cam Newton, reviews from the league.

On Thursday, the Wall Street Journal published a story, headlined "A Game Changer for Diagnosing Concussions in the NFL," about new research that "raises hopes that eventually a blood test for a concussion will be as objective as diagnosing high cholesterol or a heart attack." The article highlights a forthcoming scientific paper in the journal Neurology that, according to the WSJ, finds "a small sample of blood, drawn within six hours of a forceful impact, can be tested with the Quanterix machine to determine whether a concussion victim will be able to return safely to action within 10 days or should sit out for several weeks."

The NFL—along with every other level and sport confronting head trauma issues—faces two basic questions when it comes to addressing individual cases: 1) Does this player have a concussion? (otherwise known as sideline testing) and 2) If so, when should the player return to play? This new blood test, as described by the Journal, doesn't address the first question at all, and only somewhat helps the second.

Last January, I wrote an article titled "Are The Promises of Concussion Blood Tests Getting Ahead of the Science?," which discussed the very same biotech company, Quanterix, featured in the new study. Quanterix CEO Kevin Hrusovsky told me that the blood test had proven effective starting 45 minutes after impact—that is, the blood has to be drawn 45 minutes after impact in order to give time for the biomarkers to leak across the blood brain barrier and circulate the bloodstream. So, the test itself has to be done between 45 minutes and six hours after impact (to say nothing of how long the actual test is going to take), which rules it out as a sideline diagnosis tool. A concussed player needs to be removed from the game immediately, not 45 minutes later.

The NFL doesn't need a new test. Concussions are, generally speaking, very easy to diagnose. Concussed people can't fake memory tests or finger-following. The problem the NFL most commonly faces is not whether concussions are accurately diagnosed on the sideline but whether a player is pulled off the field for testing in the first place. That problem will persist no matter the testing method, because it comes down to the people making decisions about player health and their priorities.

As far as return-to-play issues are concerned, the new test doesn't help that, either. Again, going off the Journal's description, the test determines whether a player's symptoms will subside quickly or linger for weeks. This is something trained doctors can usually determine anyways with routine examinations. Sensitivity to light, persistent headaches, concentration issues, etc. can all be determined through examination. Yes, players can lie and deceive their way through some symptoms, but not all. Further, it doesn't seem like the test can specify how long the symptoms will persist, and since it can only be done within six hours of the injury, it leaves the biggest question—When can a player return to play?—largely unanswered.

This isn't to say the new study and the blood test is useless. Far from it. But it's mostly useful for research purposes, not for practical diagnostics. Here's what I wrote back in January:

"Approximately four out of every five head trauma victims quickly return to a normal life. The remaining patients won't be able to go to work or school and have their lives derailed as a result of their injury. Currently, researchers have no way of knowing whether any given patient will be the 80 percent or the 20 percent until the first few days and weeks pass. This makes researching potential remedies, therapies, or treatments nearly impossible, since 80 percent of your potential population will get better on their own regardless. A blood test telling you whether someone will be in the 80 percent or the 20 percent would change all that."

That is exactly the problem this blood test is solving: it can tell you whether the person will be in the 80 percent or 20 percent, so researchers can study only those who are part of the 20 percent. That's a really big deal if you're in the field of brain-injury research, but not such a big deal for everyone else. Maybe, down the line, this will lead to some important findings on what causes someone to be in the 20 percent group and how to help them, but that's a long way off.