Establishing an ICD-10 code based SARI-surveillance in Germany – description of the system and first results from five recent influenza seasons

Abstract

BackgroundSyndromic surveillance of severe acute respiratory infections (SARI) is important to assess seriousness of disease as recommended by WHO for influenza. In 2015 the Robert Koch Institute (RKI) started to collaborate with a private hospital network to develop a SARI surveillance system using case-based data on ICD-10 codes. This first-time description of the system shows its application to the analysis of five influenza seasons.MethodsSince week 40/2015, weekly updated anonymized data on discharged patients overall and on patients with respiratory illness including ICD-10 codes of primary and secondary diagnoses are transferred from the network data center to RKI. Retrospective datasets were also provided. Our descriptive analysis is based on data of 47 sentinel hospitals collected between weeks 1/2012 to 20/2016. We applied three different SARI case definitions (CD) based on ICD-10 codes for discharge diagnoses of respiratory tract infections (J09 - J22): basic CD (BCD), using only primary diagnoses; sensitive CD (SCD), using primary and secondary diagnoses; timely CD (TCD), using only primary diagnoses of patients hospitalized up to one week. We compared the CD with regard to severity, age distribution and timeliness and with results from the national primary care sentinel system.ResultsThe 47 sentinel hospitals covered 3.6% of patients discharged from all German hospitals in 2013. The SCD comprised 2.2 times patients as the BCD, and 3.6 times as many as the TCD. Time course of SARI cases corresponded well to results from primary care surveillance and influenza virus circulation. The patients fulfilling the TCD had been completely reported after 3 weeks, which was fastest among the CD. The proportion of SARI cases among patients was highest in the youngest age group of below 5-year-olds. However, the age group 60 years and above contributed most SARI cases. This was irrespective of the CD used.ConclusionsIn general, available data and the implemented reporting system are appropriate to provide timely and reliable information on SARI in inpatients in Germany. Our ICD-10-based approach proved to be useful for fulfilling requirements for SARI surveillance. The exploratory approach gave valuable insights in data structure and emphasized the advantages of different CD.

Risk factors for hospitalized respiratory syncytial virus disease and its severe outcomes

“…Further detailed description of the ICOSARI methodology was published elsewhere. 13 The ICOSARI system was approved by the RKI and HELIOS Kliniken GmbH data protection authorities. As ICOSARI involved no interventions and the analysis was based on anonymized data only, no ethical clearance was required for this study.…”

“…Data of respiratory hospitalizations have been collected through the ICOSARI. 13,14 The aim of the present study was to identify risk factors, in particular underlying medical conditions as risk factors, for hospitalized RSV disease and its severe outcomes based on the ICD-10-codebased surveillance data.…”

Evaluation of using ICD‐10 code data for respiratory syncytial virus surveillance

“…14 In secondary care, an ICD-10 code-based surveillance system for severe acute respiratory infections (ICOSARI) has been implemented in cooperation with a private hospital network in Germany. 15 Studies estimating validity of ICD diagnosis codes for the identification of laboratory-confirmed influenza have shown mixed results. 14,[16][17][18] So far, few studies have looked at accuracy of RSVspecific ICD-10 diagnosis codes for the identification of true RSV infections.…”

“…The datasets of ICOSARI for the years 2009 to 2014 were collected retrospectively. The Appendix S1 provides details on the surveillance participants, data collection methods, collected data, total number of collected data, and study period ( [13][14][15] , Appendix S1). The SEED ARE system was approved by the German Federal Commissioner for Data Protection and Freedom of Information, and the ICOSARI system by the RKI and HELIOS Kliniken GmbH data protection authority.…”

“…As SEED ARE and ICOSARI involved no interventions and the analysis was based on anonymized data only, no ethical clearance was required for them. 14,15 The virological surveillance activities were approved by the German Federal Commissioner for Data Protection and Freedom of Information and the Ethical Committee of the Charité, Universitätsmedizin, Berlin.…”