title: A qualitative systematic review of the literature supporting a causal relationship between exit-site infection and subsequent peritonitis in patients with end-stage renal disease treated with peritoneal dialysis.
abstract: OBJECTIVE
  The objective of our research was to summarize and review evidence supporting a causal relationship between exit-site infection and peritonitis in peritoneal dialysis (PD) patients.
  
  
  METHODS
  We undertook a qualitative review of studies retrieved from MEDLINE, EMBASE, and PubMed, and supplemented that process with a hand search of references and abstracts in the literature.
  
  
  METHODS
  Our quality criteria were based on the Paediatric Risk of Mortality guidelines, definitions, and recommendations from the International Society for Peritoneal Dialysis (ISPD), and the Bradford Hill criteria for causality. All identified abstracts were reviewed for content. Of 776 abstracts, 59 were selected for full-text evaluation, and 22 of those met the ISPD criteria for good-quality research in PD-related infections. Of the 22 eligible studies, 9 met the study's quality criteria and were included in the summative analysis. No articles reported sufficient data for a quantitative analysis.
  
  
  METHODS
  Information on study design, study population characteristics, definitions, peritonitis rates, exit-site care protocol, exit-site treatment protocol, follow-up period, potential bias, and outcomes was extracted. Criteria for including data in the final study were determined using ISPD guidelines.
  
  
  RESULTS
  Of the 9 included studies, 8 suggested that a history of exit-site infection increased the risk for subsequent peritonitis. Of those studies, 3 met 5 causality criteria, 4 met 4 causality criteria, and 1 met 3 causality criteria.
  
  
  CONCLUSIONS
  The literature provides weak evidence to support a causal relationship between exit-site infection and subsequent peritonitis. Few criteria for causation were met. We were unable to attribute causation and could assume an association only. The exclusion of studies focusing on PD-related tunnel infections may be viewed as both a strength and a limitation of the present work.
authors: Academic Medical Center,1 University of Amsterdam, Amsterdam, Netherlands, and Department of Medicine,2 University of Toronto, and Division of Nephrology, University Health Network, Toronto, Ontario, Canada.
authors: Anouk T N
authors: AT
authors: van Diepen
authors: Sarbjit V
authors: SV
authors: Jassal
mesh_terms: D055499:Catheter-Related Infections / Q000453:epidemiology*; D002408:Catheters, Indwelling; D015984:Causality; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D010530:Peritoneal Dialysis; D010538:Peritonitis / Q000453:epidemiology*
keywords: Bradford Hill; Exit-site infection; catheter infection; causality; infectious complications; peritonitis