Nepean Wildcats hockey player Jenna Pietrantonio thought she had whiplash after slamming into an opponent during a game in September 2013 — but it turned out to be her second concussion.

At 17, she couldn't look at her phone, sat in her bedroom with the blinds pulled for darkness and had to quit the game she loved as the after-effects of her concussion continued for months — and still linger nearly three years later.

"When is this going to go away?" she recalled asking in the emergency room immediately following her injury.

Now, a new study led by a Children's Hospital of Eastern Ontario researcher has created a validated clinical prediction score to anticipate, for the first time, how long a child or teen will experience post-concussion symptoms.

"Before this study, we had no way of answering that question. And now we actually do," said lead author Dr. Roger Zemek, a CHEO scientist and associate professor at the University of Ottawa.

Pietrantonio was one of more than 3,000 youths between the ages of five and 18 years old from across the country who took part in the study, which was published Tuesday in the Journal of the American Medical Association.

Pietrantonio is still healing from her concussion and hopes she will to be able to play hockey again one day.

"As of right now, I can't even run or anything. Hopefully in 10 years, when I'm older, I can hit the rink," she said.

9 predictors

The 5P study — predicting and preventing post-concussive problems in pediatrics — evaluated youths within 48 hours of sustaining a head injury — and in most cases, within three hours of the injury.

Dr. Roger Zemek CHEO

CHEO researcher Dr. Roger Zemek led a study to help predict the duration of post-concussion symptoms in youth. (CBC)

"We looked at all the different possibilities — whether you lost consciousness, whether you remember things and what sort of medical problems you might have had in the past. We looked at all those things and were really able to narrow it down to just a few key items," Zemek said.

Those nine predictors include demographics, history, initial symptoms, cognitive complaints and a physical examination, he said.

Zemek said the prediction score will help medical staff be more efficient with health care resources.

"We'll be able to take those kids who are at higher risk and streamline them into earlier follow-up. And conversely, the kids who are going to recover quickly, they may not need advanced, specialty care," he said.

Moving forward, he said being able to predict post-concussion symptoms will help future research.

"I wanted to do research to study what medicines are most effective. You may want not to expose a child who is going to get better in a week or two anyway to an intravenous to see if that therapy is going to work," he said.

"But I think it's so important to be able to target early intervention. It's kind of the concept of a forest fire. These things always start out as small little brush fires or small little sparks. If you put it out early, it stays out."

Persistent symptoms likelier for girls 

The study found that while more boys sustained concussions, girls were twice as likely to have post-concussion symptoms for at least one month. Known as "persistent post-concussion symptoms," they can cause youth to miss school, experience depression, and miss out on social and physical activities.

Kids and teens are more likely than adults to sustain concussions, with one-third experiencing ongoing symptoms for more than one month, including headaches and dizziness, difficulty concentrating, change in sleep patterns and emotional or behavioural symptoms, Zemek said. 

"We're trying to predict something that's really complicated," he said. "We're trying to predict something a month away within just a few hours and what we've been able to show is that we can do it a heck of a lot better than we were able to do before this study."

Children under eight were less likely to have persistent post-concussion symptoms than older children, the study found. 

Though led by CHEO, the study included data from eight other pediatric emergency departments, including Stollery Children's Hospital, Alberta Children's Hospital Research Institute, Children's Hospital of Winnipeg, Hospital for Sick Children, Children's Hospital of Western Ontario, CHU Sainte-Justine, Montreal Children's Hospital, and IWK Health Sciences Centre.