title: Body mass index and survival after in-hospital cardiac arrest.
abstract: BACKGROUND
  The quality and effectiveness of resuscitation processes may be influenced by the patient's body mass index (BMI); however, the relationship between BMI and survival after in-hospital cardiac arrest has not been previously studied.
  
  
  RESULTS
  We evaluated 21 237 adult patients with an in-hospital cardiac arrest within the National Registry for Cardiopulmonary Resuscitation (NRCPR). We examined the association between BMI (classified as underweight [<18.5 kg/m(2)], normal [18.5 to 24.9 kg/m(2)], overweight [25.0 to 29.9 kg/m(2)], obese [30.0 to 34.9 kg/m(2)], and very obese [≥35.0 kg/m(2)]) and survival to hospital discharge using multivariable logistic regression, after stratifying arrests by rhythm type and adjusting for patient characteristics. Of 4499 patients with ventricular fibrillation or pulseless ventricular tachycardia as initial rhythm, 1825 (40.6%) survived to discharge. After multivariable adjustment, compared with overweight patients, underweight (odds ratio [OR], 0.59; 95% confidence interval [CI], 0.41 to 0.84; P=0.003), normal weight (OR, 0.75; 95% CI, 0.63 to 0.89; P<0.001), and very obese (OR, 0.78; 95% CI, 0.63 to 0.96; P=0.02) had lower rates of survival, whereas obese patients had similar rates of survival (OR, 0.87; 95% CI, 0.72 to 1.06; P=0.17). In contrast, of 16 738 patients with arrests caused by asystole or pulseless electric activity, only 2501 (14.9%) survived. After multivariable adjustment, all BMI groups had similar rates of survival except underweight patients (OR, 0.67; 95% CI, 0.54 to 0.82; P<0.001).
  
  
  CONCLUSIONS
  For cardiac arrest caused by shockable rhythms, underweight, normal weight, and very obese patients had lower rates of survival to discharge. In contrast, for cardiac arrest caused by nonshockable rhythms, survival to discharge was similar across BMI groups except for underweight patients. Future studies are needed to clarify the extent to which BMI affects the quality and effectiveness of resuscitation measures.
authors.affiliation: Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Renuka
authors.initials: R
authors.lastname: Jain
authors.forename: Brahmajee K
authors.initials: BK
authors.lastname: Nallamothu
authors.forename: Paul S
authors.initials: PS
authors.lastname: Chan
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects; D005260:Female; D006323:Heart Arrest / Q000150:complications / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D006761:Hospitals; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D016019:Survival Analysis; D014693:Ventricular Fibrillation / Q000150:complications / Q000453:epidemiology* / Q000401:mortality