Exploring reference standards for the measurement of respiratory rate in children under 5 years of age: a scoping review

Sep 30, 2026

Respiratory rate is a key clinical vital sign, yet no universally accepted reference standard exists to validate measurement methods in children under five. This scoping review identifies reference standards used to evaluate respiratory rate measurement methods, and characterizes reported strengths and limitations. MEDLINE and Web of Science (English; 2013–2024) included comparative studies using a reference standard, with deductive content analysis and forest-plot assessment of agreement. Among 56 studies, impedance pneumography, manual counting, and capnography were most common, and performance varied by age, condition, setting, training, and ease of implementation. Overall relative performance remained unclear, supporting more direct cross-standard comparisons across settings.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages12

Reading Time30 min

AccessFree to download

Abstract

Background

Aim

Methods

Results

Conclusion

Introduction

Respiratory rate as a vital sign in pneumonia

Measurement challenges and available methods

Open access Original research Exploring reference standards for the measurement of respiratory rate in children under 5 years of age: a scoping review Sofia Tzirita ,1 Carina King ,1 Eric D McCollum ,2 Kevin Baker ,1,3 Miguel Bordallo López ,4,5 Mattias Schedwin 1,6 To cite: Tzirita S, King C, McCollum ED, et al. Exploring reference standards for the measurement of respiratory rate in children under 5 years of age: a scoping review. BMJ Paediatrics Open 2026;10:e003506 . doi:10 . 1136/ bmjpo-2025-003506 ► Additional supplemental material is published online only. To view, please visit the journal online ([https://doi.org/](https://doi.org/)[ ](https://doi.org/)[10.1136/bmjpo-2025-003506](10.1136/bmjpo-2025-003506)) . Received 21 March 2025 Accepted 22 December 2025 © Author(s) (or their employer(s)) 2026. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group. For numbered affiliations see end of article. Correspondence to Dr Sofia Tzirita; sofia.tzirita@ [ki.se](ki.se) ABSTRACT Background Respiratory rate is an important part of assessing the clinical state of children, and various methods exist to measure it. However, there is a lack of a universally accepted reference standard to validate the performance of these methods. Aim To identify different reference standards that have been used to evaluate respiratory rate measurement methods in children under 5 years of age and describe their perceived strengths and limitations. Methods MEDLINE and Web of Science were searched for studies in English. Studies of children under 5 years of age, published between 2013 and 2024, in which a method for measuring respiratory rate was compared against a reference standard, were included. Deductive content analysis was used to map perceived strengthsand limitations of each standard, and a forest plot analysis was used to compare agreement between the reference standard and the index tests. Results From 992 retrieved studies, 56 were included. The most common reference standard was impedance pneumography (22/56), primarily used in high-income settings, followed by manual counting (19/56), mostly employed in low-and middle-income settings, and capnography (9/56) . Child age, clinical condition, setting, training of personnel and the ease of implementation were all important factors in which the reference standard was used and how it performed. Conclusion Three different reference standards were used for most studies; however, their relative performance to each other is unclear. There is a need for research that directly compares the performance of these reference standards across different age strata and settings in order to confidently recommend a reference standard for respiratory rate measurement methods. INTRODUCTION Respiratory rate (RR) is a key vital sign, serving as a fundamental physiological marker of lung function and an important diagnostic indicator for a range of conditions,1 most notably pneumonia. Pneumonia is one of the leading causes of mortality in children under 5 years of age, with the highest occurrence in South Asia and Sub-Saharan Africa.2 RR | WHAT IS ALREADY KNOWN ON THIS TOPIC | | --- | | ⇒ Respiratory rate (RR) is a crucial vital sign for diagnosing several health conditions, such as pneumonia, especially in children aged under 5 years in low-resource settings. While new methods are being developed to improve the accuracy and feasibility of RR measurement, a unified reference standard is still lacking, impeding a comparative evaluation of their performance.
WHAT THIS STUDY ADDS | | ⇒ The most common reference standards that have been used for paediatric RR measurement are impedance pneumography, manual counting and capnography.
⇒ No single reference standard stood out as being superior to others, and the reference standards’agreement with index tests and use in studies to date is linked to factors such as age, sett

FAQs

Why is a reference standard important for measuring respiratory rate in children under 5?

Respiratory rate is crucial for assessing children’s clinical state, but methods lack a universally accepted reference standard to validate accuracy and performance.

Which reference standards were most frequently used in the included studies?

Impedance pneumography was the most common reference standard, followed by manual counting, with capnography also used in a substantial subset of studies.

What factors influenced how reference standards performed across studies?

Age, clinical condition, study setting, training of personnel, and ease of implementation were identified as important factors linked to how the reference standards were used and how well they performed.

Sep 30, 2026

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