Acute respiratory infections (ARI) are one of the most frequent reasons for hospital admission and antibiotic use, and can be caused by a broad range of pathogens, including respiratory viruses with proven epidemic potential, e.g. influenza and coronaviruses. The POS-ARI-ER study will focus on describing the different routine diagnostic and therapeutic practices in the work-up and treatment of ARI, as well as clinical outcomes across the patient population. In addition, POS-ARI-ER aims to characterise both the adult patient population with ARI presenting to acute hospital settings in Europe, and the aetiology of ARI in these patients.

The POS-ARI-ER study is a perpetual, observational study (POS), designed to provide data for clinical characterisation of acute respiratory infections (ARIs) in adults presenting to hospital settings across Europe.

Establishing the etiological cause of ARI at the time of presentation is difficult with currently available diagnostic approaches. Improvements in diagnosis and strategies for use of targeted antibiotic and antiviral treatment strategies are needed to improve patient outcomes, and to reduce selection of antimicrobial resistance (AMR) and antiviral resistance. Recent advances in routine diagnostics in secondary care settings include molecular tests that can detect multiple pathogens simultaneously, and highly sensitive and specific point of care tests that can provide attending clinicians with rapid results. However, the implementation of these technologies into routine clinical practice within hospitals, and any impact on treatment decisions or patient outcomes, has not been widely evaluated.

The aim is to accurately characterise cases of ARIs presenting to acute hospital services, such as emergency departments and acute medical assessment units, in Europe.

Characterisation will focus on identifying the routine diagnostic methods (laboratory and point of care testing) and pharmacological interventions employed by different centres in patients presenting with ARI. Data will be collected using standardised report forms that capture clinical, laboratory and prescribing information. Participants will include those who require admission to hospital, as well as patients who are discharged the same day from the emergency department or acute medical assessment unit. In addition, a subset of participants will have single upper respiratory tract research sample (e.g. nose/throat swab) obtained at enrolment (within 24 hours), for pathogen detection by molecular methods.

Describing the variations in routine practice provides a foundation both to improve patient care through currently available approaches, as well as to inform areas of focus for development of new strategies.

Inclusion Criteria:

• Age ≥ 18 years
• Clinical suspicion of a new episode of acute respiratory tract infection, with onset in the last 10 days
• Patient presents to an emergency room or secondary care setting
• Informed consent is provided by patient or their legal representative

Exclusion Criteria:

• Patient has been transferred from another hospital
• Patient admitted to hospital for >2 days at the time of enrolment
• Patient has been previously enrolled in the POS-ARI-ER study

Adult patients with community acquired acute respiratory infections presenting to acute hospital settings in Europe.