title: Body Mass Index and Aneurysmal Subarachnoid Hemorrhage: Decreasing Mortality with Increasing Body Mass Index.
abstract: BACKGROUND
  Labeled the "obesity paradox," obesity has been shown to provide a survival advantage in coronary artery disease, stroke, and intracerebral hemorrhage. Studies on body mass index (BMI) in aneurysmal subarachnoid hemorrhage (SAH) show conflicting results and none examined a North American population with long-term follow-up.
  
  
  METHODS
  A total of 305 consecutive SAH patients (2002 to 2011) were retrospectively reviewed to collect demographics, BMI (kg/m(2)), comorbidities, Glascow Coma Scale, World Federation of Neurologic Surgeons Scale, aneurysm treatment, delayed cerebral ischemia, radiographic infarction, and short-term and long-term (> 24 months) morbidity, and mortality. Patients were stratified by BMI into category 1, < 25 kg/m(2); category 2, 25 -< 30 kg/m(2); and category 3, ≥ 30 kg/m(2).
  
  
  RESULTS
  Categories 1, 2, and 3 had 93, 100, and 87 patients with mean BMIs of 22.4 ± 1.8, 27.6 ± 1.4, and 35.7 ± 4.6 (P < 0.05), respectively. By category, 24-month follow-up was available in 92%, 85%, and 85%. Category 3 had more hypertension, diabetes mellitus, and clipping than category 1. Short-term mortality rates were 17%, 12%, and 8%; long-term mortality rates were 34%, 26%, and 19% (P > 0.05 at all points between categories 1 vs. 3, but not 1 vs. 2 or 2 vs. 3). On univariate analysis, BMI was inversely associated with short-term (odds ratio, 0.91; 95% confidence interval 0.84-0.98; P = 0.009) and long-term (odds ratio, 0.92; 95% confidence interval 0.87-0.97; P = 0.001) mortality. On multivariate analysis including age, World Federation of Neurologic Surgeons Scale, delayed cerebral ischemia, and radiographic infarction, BMI remained significant for short-term (odds ratio, 0.91; 95% confidence interval 0.81-0.99; P = 0.047) and long-term (odds ratio, 0.92; 95% confidence interval 0.85-0.98; P = 0.021) mortality. On Kaplan-Meier survival analysis, P > 0.05 for categories 1 versus 2 and 2 versus 3, but P = 0.005 for categories 1 versus 3.
  
  
  CONCLUSIONS
  In our SAH population, higher BMI resulted in less short-term and long-term mortality, but no difference in functional outcome.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic and Mayo Clinic Foundation, Rochester, Minnesota, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Hughes
authors.affiliation: Aberdeen Royal Infirmary, Aberdeen, Scotland, United Kingdom.
authors.forename: Milan
authors.initials: M
authors.lastname: Samarage
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic and Mayo Clinic Foundation, Rochester, Minnesota, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Burrows
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic and Mayo Clinic Foundation, Rochester, Minnesota, USA; Department of Radiology, Mayo Clinic and Mayo Clinic Foundation, Rochester, Minnesota, USA.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lanzino
authors.affiliation: Department of Neurology, Mayo Clinic and Mayo Clinic Foundation, Rochester, Minnesota, USA. Electronic address: rabinstein.alejandro@mayo.edu.
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Rabinstein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000209:etiology* / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy; D016896:Treatment Outcome
keywords: Body mass index (BMI); Mortality; Obesity paradox; Subarachnoid hemorrhage (SAH)