title: Comparison of body mass index and body surface area as outcome predictors in patients with systolic heart failure.
abstract: BACKGROUND
  We investigated whether the 'obesity paradox' in heart failure (HF) is influenced by common confounders, and assessed if body surface area (BSA) may correlate more closely than body mass index (BMI) with prognosis.
  
  
  METHODS
  We studied 630 systolic HF patients at their initial visit to the HF clinic. Body size was measured by BMI and BSA. The association between body indices and mortality was assessed by Cox proportional-hazard analyses.
  
  
  RESULTS
  There were 248 deaths during mean follow-up of 39 months. A progressive inverse association of BMI and BSA tertiles (T1-T3) with mortality risk was observed (for BSA: T3, reference, T2, hazard ratio [HR] 1.41, 95% confidence interval [CI] 1.01-1.95, p = 0.04 and T1, HR = 1.78, 95% CI 1.29-2.45, p < 0.001; for BMI: T3, reference, T2, HR = 1.29, 95% CI 0.92-1.79, p = 0.13 and T1, HR = 1.66, 95% CI 1.21-2.27, p = 0.002). The obesity paradox was attenuated after multivariate adjustment, and did not persist after adjustment for age alone (for BMI: T3, reference, T2, HR = 1.13, 95% CI 0.81-1.58, p = 0.47; T1, HR = 1.30, 95% CI 0.94-1.80, p = 0.12; for BSA: T3, reference, T2, HR = 0.96, 95% CI 0.68-1.35, p = 0.82; T1, HR = 1.15, 95% CI 0.82-1.63, p = 0.42).
  
  
  CONCLUSIONS
  BSA provides prognostic information similar to BMI in systolic HF. However, the obesity paradox of both BMI and BSA in HF may be confounded by the younger age of the obese patients.
authors.affiliation: Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center and Heart Failure Clinic, Lin Medical Center, Haifa, Israel. barakzmd@gmail.com.
authors.forename: Barak
authors.initials: B
authors.lastname: Zafrir
authors.forename: Yaron
authors.initials: Y
authors.lastname: Goren
authors.forename: Nabeeh
authors.initials: N
authors.lastname: Salman
authors.forename: Offer
authors.initials: O
authors.lastname: Amir
mesh_terms: D000368:Aged; D015992:Body Mass Index; D001830:Body Surface Area; D016009:Chi-Square Distribution; D015986:Confounding Factors, Epidemiologic; D005260:Female; D054143:Heart Failure, Systolic / Q000150:complications* / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000150:complications / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D065840:Protective Factors; D018570:Risk Assessment; D012307:Risk Factors; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left