When stroke symptoms hit, not everyone calls 911—a decision that has perplexed experts. Now, a small study reveals some of the reasons.

The research, being presented next week at the American Stroke Association's International Stroke Conference in Honolulu, included interviews with 38 who drove themselves or had someone drive them to Baptist Health South Florida Hospitals rather than calling 911.

Lead researcher Maygret Ramirez said the most common reason, listed by nearly one-third of participants, was preference and not knowing where an ambulance would take them. Other reasons patients provided were not realizing it was an emergency, having a family member who preferred to drive, or thinking they would get to the hospital faster if they drove rather than waiting for an ambulance.

"The fact that hospital preference is the number one reason for not calling 911 tells us we need to provide better education on this issue," said Ramirez, a nurse practitioner at Baptist Health Neuroscience Center in Miami. "People really need to understand that can be a catastrophic event if not treated in time."

Patient concerns are not misguided. Guidelines recommend emergency medical teams take stroke patients to the nearest hospital that can deliver the clot-busting medicine alteplase. Ramirez said EMS teams are typically taught to refuse a patient's request to go to a different hospital.

Still, she said, that shouldn't dissuade people from calling 911. If a patient wants to go to a different hospital, "they could ask to be transferred (there) after the first assessment."

Fast action is essential in treating stroke, with early treatment leading to higher survival rates and lower disability rates. Yet previous studies have found more than one in three people who have a stroke don't call 911 and instead rely on self-transport to get to the hospital.

"We have to reinforce the idea that this is an emergency. We need more people to understand that when it comes to stroke, 'time is brain,'" Ramirez said, repeating a phrase coined in the 1990s to amplify the message that the longer you wait to treat a stroke, the higher your chance of brain damage.

Ramirez said she'd now like to see research that looks at the specific types of educational messages that will get people to call 911 during a stroke.

A stroke happens when blood vessels carrying oxygen to the brain are blocked or rupture, causing brain cells to die. In the U.S., stroke is the fifth most common cause of death. An estimated 140,000 people in the U.S. die of stroke each year. It's also a leading cause of disability.

Calling 911 for stroke is essential because it not only gets patients to the hospital faster but ensures patients are taken to a hospital that specializes in stroke treatment, according to the Centers for Disease Control and Prevention.

Dr. Kevin Sheth, an associate professor of neurology and neurosurgery at Yale School of Medicine who was not involved in the new study, said he was surprised by the results.

"I'd have thought the main reason for not calling 911 would have more to do with misinterpretation of symptoms, not hospital preference," he said. "And that raises some questions: What do we do about this? Do we need to provide more options for patients? Do we need to educate patients?"

Sheth said he's curious about whether socioeconomic and other factors such as race impacted whether people called for an ambulance. The findings are also limited by the small number of participants who were all treated at one hospital network in South Florida.

"The question of 'Why don't we get to the hospital faster?' is the biggest challenge in acute stroke research, but it's a problem we have not made much of a dent on yet," Sheth said. "Ultimately, we need to get more people to call 911 and get to definitive (stroke) therapy faster."