Definition of healthcare-associated influenza: A review and results from an international survey.

Elodie Munier‐Marion,Thomas Bénet,Philippe Vanhems

doi:10.1111/irv.12460

Abstract

AimTo describe definitions of healthcare‐associated influenza (HAI) in recent literature and in hospitals participating in a survey of Society for Healthcare Epidemiology of America (SHEA) Research Network (SRN) members.MethodA review with PubMed search was undertaken to retrieve articles published between 2008 and 2016, focusing on the subject headings “influenza, human” and “cross infection.” Definitions of clinical influenza‐like illness (ILI) and HAI were identified. An invitation to participate in the survey was sent to 218 SRN members via email.ResultsOf 75 articles on HAI included in the review, 30 presented a standardized definition of clinical ILI based on fever (100%), cough (80%), and sore throat (70%). Forty studies (53%) contained a standardized HAI definition, grounded on threshold delay from admission in 29 of them, this delay ranging from 48 to 196 hour (median: 72 hour). Fifty‐five SRN members responded to the survey, with a standardized definition of HAI adopted by 76% of them. This definition was based on clinical features for 24%, virological features for 31%, and both for 45%. Fever (mean threshold: 38.0°C) was part of the definition for 82%. The features required most frequently in the clinical definition were cough (46%) and sore throat (26%). Median threshold delay between admission and symptoms onset adopted for HAI definition was 48 hour (range: 24‐96 hour).ConclusionThis work underlined the heterogeneity of HAI definitions in different countries. A standardized definition would be helpful to evaluate HAI spread, outcomes in patients and healthcare systems, and the impact of prevention measures, including vaccination.

Highlights

Healthcare-associated influenza (HAI) is associated with significant morbidity, mortality, and costs attributed to increased length of stay, but is likely to be under-recognized.[1]
Fever was frequent in HAI definitions, but the temperature threshold was heterogeneous
Different local definitions might be justified by variability of infection control practices or populations, but the absence of a standardized delay could generate some difficulties which might lead to under-or overestimate the HAI burden, misclassify community or healthcare- associated influenza, and, impact hospital-attributable risk and control of disease spread

Summary

Introduction

Healthcare-associated influenza (HAI) is associated with significant morbidity, mortality, and costs attributed to increased length of stay, but is likely to be under-recognized.[1] Early detection leads to rapid implementation of respiratory isolation precautions and prevents nosocomial transmission between patients and healthcare personnel (HCP). Recognition could obviate extra testing and treatment. The need for a standardized definition of HAI has been underlined previously.[2] A synthesis using the Outbreak Reports and Intervention Studies of Nosocomial Infection (ORION) statement highlighted the dearth of standardized information collected during HAI outbreak investigations,[3] which limits comparability between studies. Standardized definitions of clinical influenza-like illness (ILI) were implemented in some observational and interventional studies, they differed from one another in terms of body temperature threshold, symptoms, and time interval between hospitalization and symptoms onset.[3]

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