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The Standardized Incidence Ratio as a Reliable Tool for Surgical Site Infection Surveillance

Published online by Cambridge University Press:  21 June 2016

Christophe Rioux ,
Bruno Grandbastien  and
Pascal Astagneau
Christophe Rioux*
Affiliation:
Interregional Center for the Coordination of Nosocomial Infection Control (C-CLIN Paris Nord), Paris, France
Bruno Grandbastien
Affiliation:
Interregional Center for the Coordination of Nosocomial Infection Control (C-CLIN Paris Nord), Paris, France
Pascal Astagneau*
Affiliation:
Interregional Center for the Coordination of Nosocomial Infection Control (C-CLIN Paris Nord), Paris, France
*
CHU Chenevier-Mondor, 51 avenue du marechal de Lattre de Tassigny, 94010 Créteil, France, (christophe.rioux@hmn.ap-hop-paris.fror, christophe_rioux@hotmail.com)
Paris Nord, Institut des Cordeliers, 15 Rue de l'Ecole de Medecine, 75006 Paris, France, (p.astagne@ext.jussieu.fr)
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Abstract

Objective.

To evaluate whether the standardized incidence ratio (SIR) is a more reliable tool for comparing rates and temporal trends of surgical site infection (SSI) in surgery wards than the incidence rate among patients with an National Nosocomial Infections Surveillance system (NNIS) risk index category of 0.

Design.

Observational, prospective cohort study in a sequential SSI surveillance system.

Setting.

Volunteer surgery wards in a surveillance network in northern France that annually conducted SSI surveillance for 3 months from 1998 to 2000.

Methods.

The incidence rate was the number of SSIs divided by the number of patients included, stratified by the NNIS risk index category. SIR was the observed number of SSIs divided by the expected number computed using a multiple regression model.

Results.

Overall, 26,904 patients in 67 surgery wards were enrolled. Between 1998 and 2000, the SSI incidence rate among patients with NNIS risk index category 0 decreased from 2.1% to 1.4%, which was a 33% reduction (P = .002). The SIR decreased from 1.2 (95% confidence interval [CI], 1.1-1.3) to 0.8 (95% CI, 0.7-0.9), which was a 20% decrease per year and an overall 33% reduction. The number of SSIs was significantly higher than expected in 17 of 201 surveillance periods over the 3 years. The classification of the wards according to the 2 indicators over the 3 years showed that wards with a high SIR did not consistently have the highest SSI incidence rate among patients with NNIS risk index category 0, partly because the type of surgical procedure and the duration of follow-up are not taken into account in the NNIS risk index.

Conclusion.

SIR should be considered a reliable indicator to estimate the reduction in SSI incidence that results from implementation of infection control policies and for comparison of SSI rates between wards.

Type
Original Articles
Information
Infection Control & Hospital Epidemiology , Volume 27 , Issue 8 , August 2006 , pp. 817 - 824
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2006

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