title: BMI as a Predictor for Perioperative Outcome of Laparoscopic Colorectal Surgery: a Pooled Analysis of Comparative Studies.
abstract: BACKGROUND
  There has been a long-lasting controversy about whether higher BMI is associated with worse perioperative outcomes of laparoscopic colorectal surgery. Recently, a number of newly published investigations have made it possible to draw a quantitative conclusion.
  
  
  OBJECTIVE
  We conducted this comprehensive meta-analysis to clarify the exact effect that BMI imposes on perioperative outcome of laparoscopic colorectal surgery.
  
  
  METHODS
  We systematically searched MEDLINE, Embase, and Cochrane Library databases to identify all relevant studies.
  
  
  METHODS
  Comparative studies in English that investigated perioperative outcome of laparoscopic colorectal surgery for patients with different BMIs were included. Quality of studies was evaluated by using the Newcastle-Ottawa Scale.
  
  
  METHODS
  The risk factor of interest was BMI.
  
  
  METHODS
  Effective sizes were pooled under a random-effects model to evaluate preoperative, intraoperative, and postoperative outcomes.
  
  
  RESULTS
  A total of 43 studies were included. We found that higher BMI was associated with significantly longer operative time (p < 0.001), greater blood loss (p = 0.01), and higher incidence of conversion to open surgery (p < 0.001). Moreover, BMI was a risk factor for overall complication rates (p < 0.001), especially for ileus (p = 0.02) and events of the urinary system (p = 0.03). Significant association was identified between higher BMI and risk of surgical site infection (p < 0.001) and anastomotic leakage (p = 0.02). Higher BMI might also led to a reduced number of harvest lymph nodes for patients with colorectal cancer (p = 0.02). The heterogeneity test identified no significant cross-study heterogeneity, and the results of cumulative meta-analysis, sensitivity analysis, and the publication bias test verified the reliability of our study.
  
  
  CONCLUSIONS
  Most studies included were retrospectively designed.
  
  
  CONCLUSIONS
  Body mass index is a practical and valuable measurement for the prediction of the perioperative outcome of laparoscopic colorectal surgery. Higher BMI is associated with worse perioperative outcome. More accurate conclusions, with more precise cutoff values, can be achieved by future well-designed prospective investigations.
authors.affiliation: 1 Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China 2 The Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh, United Kingdom 3 West China School of Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China 4 Division of biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Yazhou
authors.initials: Y
authors.lastname: He
authors.forename: Jiarong
authors.initials: J
authors.lastname: Wang
authors.forename: He
authors.initials: H
authors.lastname: Bian
authors.forename: Xiangbing
authors.initials: X
authors.lastname: Deng
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Wang
mesh_terms: D057868:Anastomotic Leak / Q000453:epidemiology; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data; D015992:Body Mass Index; D003106:Colon / Q000601:surgery*; D061887:Conversion to Open Surgery / Q000706:statistics & numerical data; D013505:Digestive System Surgical Procedures; D006801:Humans; D045823:Ileus / Q000453:epidemiology*; D010535:Laparoscopy; D008197:Lymph Node Excision; D009765:Obesity / Q000453:epidemiology*; D061646:Operative Time; D050177:Overweight / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology*; D012007:Rectum / Q000601:surgery*; D013530:Surgical Wound Infection / Q000453:epidemiology; D016896:Treatment Outcome