Performance of the World Health Organization (WHO) severe acute respiratory infection (SARI) case definitions in hospitalized children and youth: cross-sectional study

Abstract

Background

Respiratory tract infections with viral pathogens are frequently identified using the World Health Organization (WHO) case definition of severe acute respiratory infection (SARI), defined as fever of ≥38°Celsius, cough, onset within 10 days, and hospitalization. While there is extensive research in adults, less is known about the WHO SARI case definition performance in children and youth. We aimed to determine the performance of the WHO SARI and modified case definitions in identifying viral respiratory tract infections in hospitalized children and youth.

Methods

Retrospective observational cross-sectional study of hospitalized children (0–18 years) with an acute respiratory infection and who received a respiratory viral test at two large Canadian children’s hospitals from July 2022 to June 2023. The WHO SARI and modified SARI case definitions were evaluated overall, by virus and age, with reporting of sensitivity and specificity.

Findings

There were 2333 hospital admissions, with a median age of 2.4 years (IQR 0.8–5.0). 78% (n = 1828) had one or more viruses identified, most commonly respiratory syncytial virus (30%, n = 709). The WHO SARI definition had a sensitivity of 58% and specificity of 49% for identifying infections with a microbiologically confirmed virus. For Influenza only, the sensitivity was 71% and specificity 44%. The lowest sensitivity was among young children <3 months (28%) and 3 to <6 months (45%). Modified SARI definitions had similarly poor performance, with trade-offs of sensitivity and specificity.

Interpretation

The widely implemented WHO SARI case definition has sub-optimal performance among children and youth hospitalized with acute respiratory infections. Public health surveillance based on these case definitions may inadequately detect and monitor known and emerging infections, highlighting the need to develop an accurate and reliable SARI case definition for children and youth globally.

Funding

Public Health Agency of Canada, SickKids Foundation, BC Children’s Hospital.