Pneumonia can be acquired in the community (CAP) or during hospitalization (HAP). It is a leading cause of communicable diseases and the second cause of disability-adjusted life-years in the world (Roquilly et al., Shankar-Hari et al.). HAP is a common infectious disease, affecting up to 40% of patients on mechanical ventilation. It is a major global concern, with 500,000 cases treated annually in Europe. Despite European guidelines, the incidence remains high (Roquilly et al.), leading to significant medical consequences. Thanks to improved early detection and appropriate medical management, pneumonia-related mortality has steadily declined over the past decades. As a result, the number of patients surviving with potential long-term sequelae has increased, with risks of pulmonary function abnormalities, psychological disorders, and impaired quality of life (Shankar-Hari et al., Sipilä et al., Corrales-Medina et al., Ahmed et al.).

Cardiovascular and respiratory diseases (CVRD) are the most common pre-existing conditions in patients with pneumonia, with up to 40% of patients presenting these comorbidities at the time of pneumonia diagnosis (Roquilly et al., Nojiri et al.). The risk of severe cardiovascular and respiratory events increases after pneumonia recovery, with 14% of patients developing a CVRD event within the first year post-infection (Corrales-Medina et al., Herridge et al.), representing a 40% relative increase in CVRD risk compared to patients with CVRD without infection (Lai et al., Angriman et al.).

The objective of the ARCADIA study is to describe the incidence of cardiovascular diseases (CVD) in individuals surviving pneumonia and to compare it to that of patients with similar predisposing comorbidities for CVD but without a history of pneumonia. The investigators hypothesize that pneumonia is a cause of CVD so that patients with a history of pneumonia have a higher risk of developing CVD.

Pneumonia is a leading cause of communicable diseases and the second cause of disability-adjusted life-years in the world (Roquilly et al., Shankar-Hari et al.). Pneumonia can be acquired in the community (community-acquired pneumonia, CAP) or during hospitalization (nosocomial, or Hospital-acquired pneumonia, HAP). CAP is classically induced by virulent bacteria (such as Streptococcus pneumoniae) or viruses (Flu), and new pathogenic viruses such as SARS-CoV2 (COVID-19) can rapidly diffuse in the population.

HAP is a common infectious disease, affecting up to 40% of patients on mechanical ventilation. It is a major global concern, with 500,000 cases treated annually in Europe. Despite European guidelines, the incidence remains high (Roquilly et al.), leading to significant medical consequences. Thanks to improved early detection and appropriate medical management, pneumonia-related mortality has steadily declined over the past decades. As a result, the number of patients surviving with potential long-term sequelae has increased, with risks of pulmonary function abnormalities, psychological disorders, and impaired quality of life (Shankar-Hari et al., Sipilä et al., Corrales-Medina et al., Ahmed et al.).

Cardiovascular and respiratory diseases (CVRD) are the most common pre-existing conditions in patients with pneumonia, with up to 40% of patients presenting these comorbidities at the time of pneumonia diagnosis (Roquilly et al., Nojiri et al.). The risk of severe cardiovascular and respiratory events increases after pneumonia recovery, with 14% of patients developing a CVRD event within the first year post-infection (Corrales-Medina et al., Herridge et al.), representing a 40% relative increase in CVRD risk compared to patients with CVRD without infection (Lai et al., Angriman et al.).

The ARCADIA study is part of the HOMI-LUNG project, funded by the Horizon Europe program. HOMI-LUNG is an international and interdisciplinary initiative aiming to better understand the causal links between respiratory infections (such as pneumonia) and the progression of CVRD. Specifically, the project seeks to quantify the burden of CVRD following pneumonia, assess patient acceptability of long-term health alterations, and define pneumonia endotypes with distinct pathobiological mechanisms associated with CVRD exacerbation.

The objective of the ARCADIA study is to describe the incidence of cardiovascular diseases (CVD) in individuals surviving pneumonia and to compare it to that of patients with similar predisposing comorbidities for CVD but without a history of pneumonia. The investigators hypothesize that pneumonia is a cause of CVD so that patients with a history of pneumonia have a higher risk of developing CVD.

Inclusion Criteria:

• Be at least 18 years of age in the month of the index date.
• Exposed group: participants who declared pneumonia between January 1, 2015 and November 30, 2024.
• Unexposed group: participants who did not declare pneumonia between January 1, 2015 and index date and being selected after matching on age, sex, CVD history, chronic kidney disease, diabetes, antihypertensive deliveries, obesity, lipid-lowering treatments, alcohol and tobacco consumption.

Exclusion Criteria:

• Declared pneumonia between January 1, 2012 and December 31, 2014.
• Pneumonia before the age of 18 between January 1, 2015, and the index date.
• Organ transplant receiver for any of the following organs before or within one year after the index date: heart, kidney, lung, liver, and pancreas.
• Identifier that cannot be reliably tracked in the SNDS (such as a fictitious or provisional identifier, or an identifier that, under specific regimen, fails to distinguish same-sex twins in hospital records).
• Death during index hospitalization.

The French National Health Data System (SNDS) is a database that centralizes health-related data covering over 99% of residents (Tuppin et al.). Its primary objective is to support epidemiological research and health care system evaluation. It enables longitudinal analyses of health care pathways by linking data sources through anonymized identifiers.

SNDS include information on reimbursed outpatient care and deliveries, hospital discharge summaries and medical procedures, death and related causes and list of pathologies requiring chronic care.

These datasets collectively enable large-scale population-based studies on health care utilization, costs, morbidity and mortality. SNDS enable epidemiological studies to be conducted with more than 10 years of hindsight on nearly 68 million people.

There is not a plan to make IPD available.