Not all strokes are equally devastating, and new research shows that certain health risks don't just increase your chances of stroke, but of severe disability. A new international study identified three common factors that make it far more likely a stroke will result in death or lasting dependence. High Blood Pressure High blood pressure was the most common factor, tripling the odds of a disabling stroke and affecting nearly three-quarters of all severe stroke patients studied. Atrial Fibrillation Atrial fibrillation, an irregular heartbeat that can cause blood clots, raised the odds of a severe stroke by nearly five times in the study. Smoking Smokers had a higher likelihood of severe outcomes than non-smokers, with one in three severe stroke patients being current cigarette users at the time.