title: Efficacy of hypocaloric parenteral nutrition for surgical patients: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Hypocaloric parenteral nutrition is an underfeeding strategy that lowers energy intake to around 20 kcal/kg/d. It is believed to achieve benefits by modulating metabolic responses and alleviating hyperglycemia. This study aims to systematically review the clinical efficacy of hypocaloric parenteral nutrition on surgical patients.
  
  
  METHODS
  Medline, SCI, Embase, Cochrane Library, Chinese Biomedicine Database (CBM) and China Knowledge Resource Integrated Database (CNKI) were searched for studies published before July 1, 2010. Randomized control trials (RCTs) that compared hypocaloric PN with standard or higher energy PN in surgical patients were identified and included. Methodological quality assessment was based on Cochrane Reviewers' Handbook and modified Jadad's Score Scale. Statistical software RevMan 5.0 was used for meta-analysis.
  
  
  RESULTS
  Five trials met all inclusion criteria and were included in the final meta-analysis. There were significant reductions in infectious complications (RR, 0.60; 95%CI 0.39-0.91, P = 0.02; I(2) = 38%) and length of hospitalization (LOS) associated with receiving hypocaloric PN (MD-2.49 days, 95%CI -3.88 to -1.11, P = 0.0004; I² = 48%). Stratified analysis of the smaller trials (<60) and larger trials demonstrated that the heterogeneity between trials was mainly associated with sample size. When smaller trials were excluded, hypocaloric PN was associated with reduction in infectious complications (RR, 0.21, 95%CI 0.06-0.72, P = 0.01, I2 = 0%) and shortening of LOS (MD, -2.32 days, 95%CI -3.72 to -0.93, P = 0.001, I² = 0%).
  
  
  CONCLUSIONS
  Hypocaloric parenteral nutrition may reduce infectious complications and the length of hospitalization in post-operative patients. However, this conclusion is tentative due to patient type and sample size. Furthermore, in terms of hypocaloric PN, the actual energy amount still varies a great deal (from 15 kcal/kg/d to 20 kcal/kg/d). This suggests that further research, including larger randomized clinical trials is required.
authors.affiliation: Department of Trauma Surgery, East Branch, Sichuan Provincial People's Hospital, Sichuan Academy of Medical Sciences, No.585, Da Mian Hong He Bei Lu, Long Quan District, Chengdu 610110, PR China. cdjianghua@gmail.com
authors.forename: Hua
authors.initials: H
authors.lastname: Jiang
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Sun
authors.forename: Brook
authors.initials: B
authors.lastname: Hefright
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Charles Damien
authors.initials: CD
authors.lastname: Lu
authors.forename: Jun
authors.initials: J
authors.lastname: Zeng
mesh_terms: D031204:Caloric Restriction / Q000592:standards*; D006760:Hospitalization; D006801:Humans; D007902:Length of Stay; D010288:Parenteral Nutrition / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D013514:Surgical Procedures, Operative / Q000379:methods*