A Simulation Study to Assess Indicators of Antimicrobial Use as Predictors of Resistance: Does It Matter Which Indicator Is Used?

Elise Fortin,David L Buckeridge,Caroline Quach,Robert W Platt,Patricia S Fontela,Patrick Butaye

doi:10.1371/journal.pone.0145761

Abstract

ObjectiveIndicators of antimicrobial use have been described previously, but few studies have compared their accuracy in prediction of antimicrobial resistance in hospital settings. This study aimed to identify conditions under which significant differences would be observed in the predictive accuracy of indicators in the context of surveillance of intensive care units (ICUs).MethodsTen resistance / antimicrobial use combinations were studied. We used simulation to determine if Québec’s network of 81 ICUs or the National Healthcare Safety Network (NHSN) of 2952 ICUs are large enough to allow the detection of predetermined differences between the most accurate and 1) the second most accurate indicator, and 2) the least accurate indicator, in more than 80% of simulations. For each indicator, we simulated absolute errors in prediction for each ICU and each 4-week period, for surveillance lasting up to 5 years. Absolute errors were generated following a binomial distribution, using mean absolute errors (MAEs) observed in 9 ICUs as the average proportion; simulated MAEs were compared using t-tests. This was repeated 1000 times per scenario.ResultsWhen comparing the two most accurate indicators, 80% power was reached less often with the Québec network versus the NHSN (0/20 versus 2/20 scenarios, with 5 years of surveillance data), a finding reinforced when comparing the most and least accurate indicators (3/20 versus 20/20 scenarios). When simulating 1 year of data, scenarios reaching an 80% power dropped to 0/20, comparing the two most accurate indicators with the larger network, and to 1/20, comparing the most and least accurate indicators with the smaller network.ConclusionMost of the time (72%), identifying an indicator of antimicrobial use predicting antimicrobial resistance with a better accuracy was not possible. The choice of an indicator for an eventual surveillance system should rely on criteria other that predictive accuracy.

Highlights

Surveillance of both antimicrobial resistance and population antimicrobial use are necessary to understand the magnitude of resistance problems in hospitals and obtain data for the development of tailored interventions
Simulation Study on Antimicrobial Use and Prediction of Resistance funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
The World Health Organization recommends the use of defined daily doses per patientdays, the American National Healthcare Safety Network prefers days of treatment per patient-days, while the European Surveillance of Antimicrobial Consumption measures hospital antimicrobial use with point prevalence surveys.[10,11,12]

Summary

Introduction

Surveillance of both antimicrobial resistance and population antimicrobial use are necessary to understand the magnitude of resistance problems in hospitals and obtain data for the development of tailored interventions. In Canada, surveillance of selected resistant microorganisms is already ongoing but surveillance of hospital antimicrobial use is very limited.[1,2,3] The Québec Ministry of Health has recommended the development of local surveillance in Québec healthcare facilities.[4] The optimal way to measure antimicrobial use in hospital populations, to complete surveillance of resistance, is unclear and has been the object of long lasting debates.[5,6,7,8,9]. We conducted a systematic literature review aiming to identify such studies, as long as they included pediatric populations and we found only one study comparing indicators’ correlation with resistance. [20] This study compared two of the 26 different indicators reported in the literature.[21]

Methods

Results

Conclusion