The Effects of Body Mass Index on In-hospital mortality following first ischemic or hemorrhagic stroke events: Does the “obesity paradox” apply?

Background: While it is widely held that obesity is a risk factor for stroke, its role in mortality after stroke is less understood. We aim to examine effects of Body Mass Index (BMI) on in-hospital mortality after non-subarachnoid, subarachnoid, and ischemic stroke. Methods: Retrospective cohort study. Patients aged ≥18 years, who were hospitalized in Florida hospitals between 2008 and 2012 with a diagnosis of first-time stroke as reported by the Agency for Health Care Administration (AHCA). The main independent variable was BMI category, which was divided into non-overweight/non-obese, obese, and morbidly obese. The primary outcome was the adjusted odds ratio (aOR) for in-hospital mortality for subarachnoid and non-subarachnoid hemorrhagic stroke, and ischemic stroke. Logistic regression modeling was utilized to examine the association between each BMI category and in-hospital mortality, while controlling for several potential confounders. This study was reported in line with the STROCSS criteria. Results: Of the 333,367 patients included in the database, 150,153 (45.0%) patients met inclusion criteria. After adjusting for age, gender, ethnicity and other possible confounders, obese patients were 21% less likely to die during their hospitalization following a first ischemic stroke (0.79 aOR, 0.69–0.92, 95% CI, p = 0.002), and 32% less likely following a first non-subarachnoid hemorrhage (0.68 aOR, 0.57–0.82, 95% CI, p = 0.0001) compared to non-overweight/non-obese counterparts. Conclusion: Obese patients are less likely to die during hospitalization following first-time non-subarachnoid hemorrhage and ischemic stroke than non-overweight/non-obese patients. These findings support the “obesity paradox” concept, though more research is needed for recurrent stroke patients.