title: Ventriculoperitoneal shunt survival in children who require additional abdominal surgery--are our estimations of the additional risk accurate?
abstract: OBJECTIVE
  Ventriculoperitoneal shunt (VPS)-dependent children require abdominal surgery for many reasons. Our objective was to quantify the risk of abdominal surgery on VPS survival and to determine whether timing of abdominal intervention impacts on shunt outcome.
  
  
  METHODS
  Retrospective data collection was performed on all children undergoing primary VPS insertion or revision over 2 years (1/1/08-31/12/10). All shunt interventions were categorised into two groups: those undergoing additional "Abdominal surgery" (AS) versus those undergoing "Shunt-only" (SO). Kaplan-Meier survival curves were devised and analysed using log-rank. In the AS group, we compared shunt survival for shunts inserted at various "Time from abdominal surgery" (TAS). We conducted a control analysis to compare shunt survival in AS, SO and a control "clean general surgery" (SG) group. Chi-squared test was used to determine the cause of shunt failure in these three groups.
  
  
  RESULTS
  Three hundred and forty two shunts from 109 patients were included. Twenty patients contributed 118 shunts to the AS group. Median shunt survival was 3.68 months (95% CI = 1.01-6.47) and 22.6 months (95% CI = 8.76-36.4) in the AS and SO groups, respectively (log-rank = 16.6, p < 0.001). For each additional abdominal intervention, the risk of shunt failure increased by 55.4% (p < 0.001). Median shunt survival was 1.48 months (95% CI = 0.00-3.09, p < 0.001), if shunt insertion occurred within 1 year of abdominal surgery. Beyond 1 year, median shunt survival increased five-fold to 7.65 months (95% CI = 0.00-20.1, log-rank = 23.2, p < 0.001). There was a 29% reduction in risk of shunt failure per year interval between a shunt and an abdominal surgery (95% CI = 0.11-0.44, p < 0.005). Our control analysis confirmed that shunts in the AS group had worst survival and infection (p < 0.001).
  
  
  CONCLUSIONS
  Additional abdominal surgery shortens VPS lifetime and increases risk of infection. Delaying abdominal surgery from a shunt intervention or vice versa by at least 1 year may prolong shunt survival.
authors.affiliation: The University of Manchester , Manchester , United Kingdom.
authors.forename: Angela
authors.initials: A
authors.lastname: Li Ching
authors.forename: Gill
authors.initials: G
authors.lastname: Humphrey
authors.forename: Ian D
authors.initials: ID
authors.lastname: Kamaly-Asl
mesh_terms: D000005:Abdomen / Q000601:surgery*; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D013505:Digestive System Surgical Procedures / Q000706:statistics & numerical data*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D008297:Male; D012086:Reoperation; D012189:Retrospective Studies; D018570:Risk Assessment; D013997:Time Factors; D016896:Treatment Outcome; D017287:Ventriculoperitoneal Shunt / Q000009:adverse effects / Q000145:classification