If you’re going to be attending a motorcycle rally, you might want to check your organ donor card before you go, because the chances of it becoming a relevant issue rise starkly.

That’s the grim conclusion researchers at the University of California San Francisco and the NYC Health + Hospitals in New York City found after looking at the correlation between organ donations, organ recipients, and motorcycle rallies, according to MedPage Today.

The people behind the study looked at transplant data during the nine days that the mean motorcycle rally lasts and found that there were 14 percent more organ donors and 19 percent more transplant recipients per day, as compared to non-rally dates. That amounts to 406 organ donors and 1,400 recipients over all nine days.

Read: Watch Motorcyclist Collide Head On With A Deer At 54MPH After Exiting Corner

The team also looked at the four weeks before and after motorcycle rallies. It found that there are an estimated 21 percent more organ donors per day and 26 percent more transplant recipients per day in that period, as compared to the rest of the year. Over the entire period, they found that there were 2,332 organ donors and 7,714 transplant recipients.

“Because the timing of these rallies is plausibly unrelated to demand for organs and because we found no such effect for non-motor vehicle-related donor deaths, our findings are likely due to an increase in motorcycle use in areas where large rallies are held,” wrote the study’s authors in JAMA Internal Medicine.

They found that the mean age of donors in the period of time surrounding the rallies was 32.5, while the mean age of those receiving the organs was 49.3. Of the donors, 70.9 percent were men, while 64 percent of the recipients were men.

The researchers looked at data from the Scientific Registry of Transplant Recipients from 2005 to 2021. They focused on areas where the following seven motorcycle rallies were held: Atlantic Beach Bikefest in South Carolina, the Bikes, Blues & BBQ in Arkansas, Daytona Bike Week in Florida, Laconia Motorcycle Week in New Hampshire, Myrtle Beach Bike Week Spring Rally in South Carolina, the Republic of Texas Biker Rally in Austin, and the Sturgis Motorcycle Rally in South Dakota.

“These findings are not surprising given the high mortality associated with motorcycle accidents,” the authors wrote. “The findings of [this study] provide a reminder to practice safety while practicing high-risk activities and to consider opting-in to become an organ donor to help save lives.”