Surveillance of severe acute respiratory infections associated with SARS-CoV-2, influenza virus and RSV using ICD-10 codes: a case definition accuracy study across five European countries, 2021 to 2023
Sanchez Ruiz, Miguel Angel Marques, Diogo FP Lomholt, Frederikke Kristensen Vestergaard, Lasse Skafte Monge, Susana Lozano Álvarez, Marcos Aspelund, Gudrun Thordardottir, Marianna Dziugyte, Ausra Cauchi, John-Paul
Sanchez Ruiz, Miguel Angel
Marques, Diogo FP
Lomholt, Frederikke Kristensen
Vestergaard, Lasse Skafte
Monge, Susana
Lozano Álvarez, Marcos
Aspelund, Gudrun
Thordardottir, Marianna
Dziugyte, Ausra
Cauchi, John-Paul
Series / Report no.
Open Access
Type
Journal Article
Article
Article
Language
en
Date of publication
2025-07-01
Year of publication
Research Projects
Organizational Units
Journal Issue
Title
Surveillance of severe acute respiratory infections associated with SARS-CoV-2, influenza virus and RSV using ICD-10 codes: a case definition accuracy study across five European countries, 2021 to 2023
Translated Title
Published in
Euro Surveill 2025; 30(27):2400748
Abstract
BACKGROUNDSurveillance of severe acute respiratory infections (SARI) using ICD-10 codes from electronic health records (EHR) lacks consensus on optimal case-defining codes.AIMWe determined codes that maximise sensitivity (Se) and positive predictive value (PPV) for SARI associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza virus and respiratory syncytial virus (RSV) in Denmark, Iceland, Malta, Norway and Spain.METHODSWe included hospitalisations from week 21/2021 to 39/2023, with ICD-10 diagnostic codes for respiratory disease (three-character codes J00-J99) or COVID-19 (U07.1, U07.2, country-specific codes for Denmark). We assessed Se and PPV of individual codes against laboratory results. Based on Se and PPV rank-sum, we selected the top 10 codes and combined them into 10 sets per pathogen. We identified sets that maximised the clinical utility index (CUI = Se × PPV), categorised as excellent (≥ 0.81), good (0.64-0.80), satisfactory (0.49-0.63) and poor (< 0.49).RESULTSWe assessed 395,163 hospitalisations for SARI-SARS-CoV-2, 313,418 for SARI-influenza and 192,936 for SARI-RSV, all tested. For SARI-SARS-CoV-2, code U07.1 (B34.2A, B97.2A for Denmark) had excellent utility in Denmark, Malta, Norway, Spain (≥ 0.82), and good utility in Iceland (0.79). For SARI-influenza, J09, J10 and J11 performed excellently in Denmark, Norway, Spain (≥ 0.83), satisfactorily in Malta (0.52), and poorly in Iceland (0.43). For SARI-RSV, J12, J20 and J21 achieved highest CUI but had poor utility (0.17-0.34).CONCLUSIONSCOVID-19- and influenza-specific three-character ICD-10 codes accurately identified SARI associated with SARS-CoV-2 and influenza virus. For SARI-RSV, four-character codes should be explored. We recommend context-specific assessments in countries adopting EHR-based surveillance.