The relationship between seasonal influenza and telephone triage for fever: A population-based study in Osaka, Japan

Abstract

Background: Replacing traditional surveillance with syndromic surveillance is one of the major interests in public health. However, it is unclear whether the number of influenza patients is associated with the number of telephone triages in Japan. Methods: This retrospective, observational study was conducted over the six-year period between January 2012 to December 2017. We used the dataset of a telephone triage service in Osaka, Japan and the data on influenza patients published from the Information Center of Infectious Disease in Osaka prefecture. Using a linear regression model, we calculated Spearman’s rank-order coefficient and R 2 of the regression model to assess the relationship between the number of telephone triages for fever and the number of influenza patients in Osaka. Furthermore, we calculated Spearman’s rank-order coefficient and R 2 between the predicted weekly number of influenza patients from the linear regression model and the actual weekly number of influenza patients for each season (January-March, April-June, July-September, October-December). Results: There were 465,971 patients with influenza, and the number of telephone triages for fever was 420,928 among 1,065,628 total telephone triages during the study period. Our analysis showed that the Spearman rank-order coefficient was 0.932 and R 2 and adjusted R 2 were 0.869 and 0.842, respectively. The highest Spearman rank-order coefficient was 0.896 ( P <0.001) and R 2 was 0.803 in January-March ( P <0.001). Conclusion: In this population, we revealed a positive relationship between the number of influenza patients and the number of telephone triages for fever, especially in January-March.

Effectiveness of early warning systems in the detection of infectious diseases outbreaks: a systematic review

“…Notably, the timeliness of the telephone triaging EWSs varies with resource availability. However, there was evidence that telephone triaging-EWSs has several system limitations such as overlooking small localized outbreaks and less sensitivity during pandemics, besides objective reporting [28,29].…”

“…For instance, Caudle et al declared that the lack of necessity to aggregate data from unlinked sources is an advantage for Telehealth over ED-based EWSs [24]. The Japanese telephone triaging successfully detected seasonal influenza and pediatric rotavirus outbreaks by surveillance of fever and diarrhea, respectively [28,29].…”

“…Cooper et al expanded that the NHS24's full capacity will not be reached unless there is a huge surge in call rates [25]. Eventually, in the case of pediatric infectious diseases such as Rotavirus, objective reporting of symptoms by children's parents represents a bias [28,29].…”