title: Low body mass index in adolescent idiopathic scoliosis: relationship with pre- and postsurgical factors.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To determine the association between low preoperative body mass index (BMI) and outcome of spinal fusion in adolescent idiopathic scoliosis (AIS).
  
  
  BACKGROUND
  Several studies report a lower weight and BMI in untreated subjects with AIS than nonscoliotic age-matched controls. However, very little is known about the clinical impact of low BMI on pre- or postsurgical parameters in this patient group.
  
  
  METHODS
  Seventy-seven eligible patients with AIS who underwent 1-stage posterior spinal fusion and correction at 2 tertiary centers (January 2010-April 2012) were included. Preoperative weight, corrected height, and BMI values were converted to z scores using the British 1990 growth reference data. Relationships between anthropometric indices and comorbidities, laboratory blood data, radiographical outcomes, length of hospital stay, and perioperative complications were examined, and the independent factors associated with low BMI (z score < -1) evaluated using binary logistic regression analysis.
  
  
  RESULTS
  In this AIS cohort (mean age, 15.04 yr; n = 72 females), 21 subjects (27.3%) had a low preoperative BMI; of these, 5 cases (6.5%) were considered severely thin. Lower BMI and weight z scores correlated with a greater percent correction of thoracic curves (rs = -0.287 and rs = -0.257, respectively, P < 0.05). In both the univariate and multivariate regression analysis, low BMI was significantly associated with preoperative asthma incidence (adjusted odds ratio 5.33, P = 0.023) and prolonged prothrombin time (adjusted odds ratio 4.53, P = 0.027), in addition to postoperative ileus development (adjusted odds ratio 11.96, P = 0.019). Preoperative Cobb angle, estimated intraoperative blood loss and length of hospital stay did not significantly differ between the BMI groups.
  
  
  CONCLUSIONS
  Significantly increased preoperative coagulation abnormality and asthma incidence as well as a greater percent correction of thoracic curves were associated with low BMI in this series. It was also found that postoperative ileus was independently associated with low BMI.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedic Surgery, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland †The National Children's Research Centre, Crumlin, Dublin, Ireland ‡Midwestern Limerick Hospital, Dooradoyle, Co. Limerick, Ireland §Department of Anaesthetics, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland ¶Blackrock Clinic, Blackrock, Co. Dublin, Ireland; and ‖Our Lady's Children's Hospital, Crumlin, Dublin, Ireland.
authors.forename: Roslyn C
authors.initials: RC
authors.lastname: Tarrant
authors.forename: Sam
authors.initials: S
authors.lastname: Lynch
authors.forename: Padraig
authors.initials: P
authors.lastname: Sheeran
authors.forename: Padhraig F
authors.initials: PF
authors.lastname: O'Loughlin
authors.forename: Michelle
authors.initials: M
authors.lastname: Harrington
authors.forename: David P
authors.initials: DP
authors.lastname: Moore
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Kiely
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology*; D011300:Preoperative Care / Q000379:methods; D012189:Retrospective Studies; D012600:Scoliosis / Q000453:epidemiology* / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000639:trends