Decoding community-acquired pneumonia: a systematic review and analysis of diagnostic criteria and definitions used in clinical trials

Background: Community-acquired pneumonia (CAP) is a frequent and potentially life-threatening condition. Even though the disease is common, evidence on CAP management is often of variable quality. This may be reinforced by the lack of a systematic and homogeneous way of defining the disease in randomised controlled trials (RCTs).

Objectives: To assess the diagnostic criteria and the definitions of the term "community-acquired" used in RCTs on CAP management.

Data sources: Based on the protocol (PROSPERO 2019 CRD42019147411), we conducted a systematic search on MEDLINE/PubMed and Cochrane CENTRAL for RCTs, published or registered between 2010 and 2024.

Study eligibility criteria: Completed and ongoing RCTs.

Participants: Adults hospitalised with CAP.

Methods of data synthesis: Data were collected using a tested extraction sheet, as endorsed by the Cochrane Collaboration. After cross-check, data were synthesised in a narrative and tabular form.

Results: In total, 7,173 records were identified through our searches. After removing records not fulfilling the eligibility criteria, 170 studies were included. Diagnostic criteria were provided in 69.4% of studies, and the term "community-acquired" was defined in 55.3% of studies. The most frequently included diagnostic criteria were pulmonary infiltrates (94.1%), cough (78.8%), fever (77.1%), dyspnoea (62.7%), sputum (57.6%), auscultation/percussion abnormalities (55.9%), and chest pain/discomfort (52.5%). The different criteria were used in 87 different sets across the studies. The term "community-acquired" was defined in 57 different ways.

Conclusions: The diagnostic criteria and definitions of CAP in RCTs exhibit significant heterogeneity. Standardising these criteria in clinical trials is crucial to ensure comparability across studies.