title: A prospective analysis of the inter-relationship between lung volume reduction surgery and body mass index.
abstract: OBJECTIVE
  LVRS is thought to result in significant improvements in BMI. Patients with a higher BMI at the time of diagnosis of COPD are known to have better survival, and those with a low BMI prior to LVRS have significantly worse perioperative morbidity. We aimed to assess the influence of BMI on the outcome of LVRS in our own experience.
  
  
  METHODS
  Complete preoperative BMI data was available in 114 of 131 consecutive patients who have undergone LVRS since 1995. These patients were arbitrarily classified into three categories: underweight (BMI<or=19 kg/m2), normal (BMI 20-25 kg/m2) and overweight (BMI>26 kg/m2). The in-hospital course and perioperative change in BMI at 3, 6, 12, 24 and 36 months were prospectively recorded for each category and compared.
  
  
  RESULTS
  There were no significant differences in preoperative variables except BMI. There were significantly more postoperative ITU admissions among the lowest two BMI groups (12/29, 18/58 and 3/27 patients, respectively, p=0.02), and significantly shorter hospital stay in overweight patients [16 days (5-79) vs 18 days (6-111) vs 13 days (6-25), respectively, p=0.005, expressed as median (range)]. However, there was no difference in survival between the three groups (p=0.21). Postoperative physiological improvements in the first year were related to preoperative BMI for both FEV1 (r=0.29, p=0.02) and DLCO (r=0.33, p=0.02). Postoperative BMI significantly increased in the underweight yet significantly decreased in the overweight at all time points.
  
  
  CONCLUSIONS
  The perioperative course of LVRS and its physiological benefits are influenced by preoperative BMI. Whilst the treatment of the underweight is more complicated, LVRS may be the only way of increasing their BMI. Future work is needed to explore the roles of changing energy requirements and body composition following LVRS.
authors.affiliation: Department of Thoracic Surgery, Glenfield Hospital, Groby Road, Leicester LE3 9QP, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Vaughan
authors.forename: Inger F
authors.initials: IF
authors.lastname: Oey
authors.forename: Michael C
authors.initials: MC
authors.lastname: Steiner
authors.forename: Mike D L
authors.initials: MD
authors.lastname: Morgan
authors.forename: David A
authors.initials: DA
authors.lastname: Waller
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000150:complications; D011013:Pneumonectomy; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D016019:Survival Analysis; D013851:Thinness / Q000150:complications; D016896:Treatment Outcome