Hospital discharge diagnoses in patients with SARS-CoV-2 infection in the first months of COVID-19 outbreak in the Italian province of Udine

On 20 March 2020, the Italian Ministry of Health, in collaboration with the Italian Collaborating Centre for the WHO Family of International Classifications (WHO-FIC), issued guidelines for coding the hospital discharge diagnoses for diseases caused by SARS-CoV-2 (COVID-19) (Ministero della Salute, 2020), which were subsequently adopted by all of the Italian Regions. However, in some Regions most heavily hit by the SARS-CoV-2 outbreak, different indications had already been given to hospitals before the national guidelines were ready: for example, in Emilia- Romagna, the regional indication (10 March) was to use ICD-9-CM code 480.3 (Pneumonia due to SARSassociated coronavirus) for COVID-19 patients with pneumonia, and code 079.82 (SARS-associated coronavirus) for those without pneumonia (Regione Emilia-Romagna, 2020). Analogous indications were given by the Piedmont Region (17 March) (Regione Piemonte, 2020). Instead, the national guidelines recommended to use code 484.8 (Pneumonia in other infectious diseases classified elsewhere) as the main discharge diagnosis in patients with pneumonia, followed by code 078.89 (Other specified diseases due to viruses) as a secondary diagnosis. In addition, according to the Ministry of Health, codes 079.82 and 079.99 (Unspecified viral infection) should never be used in SARS-CoV-2 infections.