In some cases, the benefit might not even be known because the patient has aged out of the population studied in clinical trials. For instance, nearly half of people with multiple sclerosis (MS) are older than 55 years, but clinical trials of disease-modifying therapies, available for 3 decades, excluded them, said Corboy, codirector of the Rocky Mountain Multiple Sclerosis Center. “The data supporting the use of these medications over age 55 are basically nonexistent,” he said.