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 strengths and 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.