ACR Appropriateness Criteria® Acute Respiratory Illness in Immunocompetent Patients: 2024 Update

Acute respiratory illness is one of the leading causes of morbidity and mortality amongst infectious diseases worldwide and a major public health issue. Even though most cases are due to self-limited viral infections, a significant number of cases are due to more serious respiratory infections where delay in diagnosis can lead to morbidity and mortality. Imaging plays a key role in the initial diagnosis and management of acute respiratory illness. This document reviews the current literature concerning the appropriate role of imaging in the diagnosis and management of the immunocompetent adult patient initially presenting with acute respiratory illness. Imaging recommendations for adults presenting with asthma or chronic obstructive pulmonary disease exacerbations are discussed. Finally, guidelines for follow-up imaging in suspected pneumonia cases to ensure occult malignancy is not overlooked. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or intermediate, experts may be the primary evidentiary source available to formulate a recommendation.