Abstract
Introduction: :
Endophthalmitis remains a serious and potentially blinding complication of cataract surgery with an overall incidence of ∼0.14% or 1 in 700 operations. Despite this knowledge of overall frequency healthcare providers find themselves confronted with clusters of cases where the appropriate level of response to the cluster is uncertain.
Purpose: :
To illustrate, by means of Monte Carlo simulation models, the likelihood of random clustering of cases arising in units within a healthcare setting resembling the UK NHS and separately within the practices of individual surgeons.
Methods: :
Simulation models were constructed within a programming language in which individual cataract operations were simulated with a 1 in 700 likelihood of each operation resulting in a ‘case of endophthalmitis’. Random clustering of ‘cases of endophthalmitis’ was observed in the models and ‘outbreaks’ were noted and tracked for various outbreak definitions.
Results: :
The model outputs are presented graphically as the proportion of ‘simulated units’ affected by an ‘outbreak’ in a year and separately as the proportion of surgeons affected for a range of ‘outbreak definitions’, e.g. 2 cases in 300 or 5 cases in 2000 operations.
Conclusions: :
These data presentations are easy to use and should facilitate a better understanding of shifts from endemic to epidemic rates of endophthalmitis with appropriate investigation of situations where a remediable common cause may exist. (Full manuscript in press: Eye 2006)
Keywords: clinical (human) or epidemiologic studies: outcomes/complications • endophthalmitis