Background: Pneumonia is the leading cause of death in children globally. In low- and middle-income countries the diagnosis of pneumonia relies heavily on an accurate assessment of respiratory rate, which can be unreliable in nurses and clinicians with less advanced training. In order to inform more accurate measurements, we investigate the repeatability of the RRate app used by nurses in district hospitals in Uganda. Methods: This planned secondary analysis included 3679 children aged 0-5 years. The dataset had two sequential measurements of respiratory rate using the RRate app. We measured the agreement between respiratory rate observations and clustering around fixed thresholds defined by WHO for fast breathing, which are 60 breaths per minute (bpm) for under two months (Age-1), 50 bpm for two to 12 months (Age-2), and 40 bpm for 12.1 to 60 months (Age-3). We then assessed the repeatability of the paired measurements using the Intraclass Correlation Coefficient (ICC).  Results: The respiratory rate measurement took less than 15 seconds for 7,277 (98.9%) of the measurements. Despite respiratory rates clustering around the WHO fast-breathing thresholds, the breathing classification based on the thresholds was changed in only 12.6% of children. The mean (SD) respiratory rate by age group was 60 (13.1) bpm for Age-1, 49 (11.9) bpm for Age-2, and 38 (10.1) for Age-3, and the bias (Limits of Agreements) were 0.3 (-10.8 – 11.3), 0.4 (-8.5 – 9.3), and 0.1 (-6.8, 7.0) for Age-1, Age-2, and Age-3 respectively. Most importantly, the repeatability of the two respiratory rate measurements for the 3,679 children was high, with an ICC value (95% CI) of 0.95 (0.94 – 0.95).   Discussion: The RRate measurements were both efficient and repeatable. The simplicity, repeatability, and efficiency of the RRate app used by healthcare workers in LMICs supports more widespread adoption for clinical use.

The authors have declared no competing interest.

(ID: H19-02398 H20-00484) (ID: 743) (ID: HS528ES)

https://clinicaltrials.gov/study/NCT04304235

Funding This research was funded by the Wellcome Trust UK (Wellcome Trust Innovator Award (ID: 215695/B/19/Z)), Mitacs Accelerate, Sepsis Canada, and BioTalent Canada.

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Ethical considerations The parent study was approved by the institutional review boards at the University of British Columbia in Canada (ID: H19-02398 H20-00484), the Makerere University School of Public Health in Uganda (ID: 743) and the Uganda National Council for Science and Technology (ID: HS528ES). All participants consented to use of their data for secondary analyses. A parent or guardian provided written informed consent prior to enrollment. In addition, assent was required from children aged older than 8 years. Data for the retrospective study was accessed on January 27, 2022, and there was no access to identifying patient data.

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