Suggestion of a simpler and faster influenza-like illness surveillance system using 2014\u20132018 claims data in Korea

Heekyoung Choi,Euna Han,Won Suk Choi

doi:10.1038/s41598-021-90511-0

Abstract

Influenza is an important public health concern. We propose a new real-time influenza-like illness (ILI) surveillance system that utilizes a nationwide prospective drug utilization monitoring in Korea. We defined ILI-related claims as outpatient claims that contain both antipyretic and antitussive agents and calculated the weekly rate of ILI-related claims, which was compared to weekly ILI rates from clinical sentinel surveillance data during 2014–2018. We performed a cross-correlation analysis using Pearson’s correlation, time-series analysis to explore actual correlations after removing any dubious correlations due to underlying non-stationarity in both data sets. We used the moving epidemic method (MEM) to estimate an absolute threshold to designate potential influenza epidemics for the weeks with incidence rates above the threshold. We observed a strong correlation between the two surveillance systems each season. The absolute thresholds for the 4-years were 84.64 and 86.19 cases per 1000claims for claims data and 12.27 and 16.82 per 1000 patients for sentinel data. The epidemic patterns were more similar in the 2016–2017 and 2017–2018 seasons than the 2014–2015 and 2015–2016 seasons. ILI claims data can be loaded to a drug utilization review system in Korea to make an influenza surveillance system.

Highlights

Influenza is an important public health concern
We collected a total of 208 weeks of influenza-like illness (ILI) data from Korea Centers for Disease Control and Prevention (KCDC) and outpatient claims data from the National Health Insurance (NHI) system from 2014 to 2018
The influenza surveillance system of Korea is operated by the KCDC and consists of the three systems; clinical sentinel surveillance, laboratory sentinel surveillance, and an influenza hospitalization and mortality surveillance system[3,4]

Summary

Introduction

We propose a new real-time influenza-like illness (ILI) surveillance system that utilizes a nationwide prospective drug utilization monitoring in Korea. In Korea, such a system is currently based on a clinical sentinel surveillance system, a laboratory sentinel surveillance system, and a hospitalization and mortality monitoring system, all of which use information collected from a restricted number of selected outpatient clinics[3,4] This traditional influenza surveillance system is considered the gold standard for relevant studies and public interventions[5,6,7]. The clinical sentinel surveillance system reports the proportion of influenza-like illness (ILI) visits among weekly outpatients through the voluntary participation of 200 local clinics nationwide. This system has been well used in Korea for a long time[8]. We defined ILI-related prescription claims, calculated the rate of the ILI-related claims among the total claims, and assessed its association with the existing clinical sentinel surveillance system

Methods

Results

Conclusion