title: Investigation into postoperative endophthalmitis and lessons learned.
abstract: OBJECTIVE
  To describe an approach to the investigation of a series of endophthalmitis cases to determine whether there was a true outbreak.
  
  
  METHODS
  Outpatient facility, Sunderland, England.
  
  
  METHODS
  Different approaches to statistical analysis of the probability of infrequent events being due to chance occurrence are described. Potential factors leading to an outbreak were reviewed.
  
  
  RESULTS
  Bayesian statistical analysis was shown to be appropriate in the determination of an endophthalmitis outbreak. The only factor found to account for the outbreak was the operating surgeon's recent abandonment of subconjunctival antibiotic prophylaxis. This decision was based on the absence of good evidence that subconjunctival antibiotic injection is effective in prophylaxis. These endophthalmitis cases demonstrate that the absence of evidence for effect is not the same as there being no effect.
  
  
  CONCLUSIONS
  Bayesian statistical analysis has a place in determining whether an outbreak has occurred. Withdrawing treatment simply on the basis of a lack of good evidence can lead to undesirable outcomes.
authors.affiliation: Sunderland Eye Infirmary, Sunderland 2R2 9HP, England, UK.
authors.forename: Kaveri
authors.initials: K
authors.lastname: Mandal
authors.forename: Anthony
authors.initials: A
authors.lastname: Hildreth
authors.forename: Malcolm
authors.initials: M
authors.lastname: Farrow
authors.forename: David
authors.initials: D
authors.lastname: Allen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D002387:Cataract Extraction; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D009877:Endophthalmitis / Q000453:epidemiology* / Q000382:microbiology; D004739:England / Q000453:epidemiology; D015818:Eye Infections, Bacterial / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology