Effect of paediatric lung ultrasound on antibiotic prescriptions in hospitalised children and adolescents with lower respiratory tract infections: protocol for a randomised, sham-controlled trial (PLUS-AP trial).

introductionLower respiratory tract infections (LRTIs) remain a major global health problem and a leading cause of childhood morbidity and mortality worldwide. Inappropriate antibiotic use for predominantly viral LRTIs is common and contributes substantially to the public health threat of antimicrobial resistance. Lung ultrasound (LUS) is a radiation-free, bedside imaging tool with high diagnostic accuracy for paediatric pneumonia. We hypothesise that integrating LUS into the care of children hospitalised with LRTIs can improve antibiotic decision-making and safely reduce unnecessary antibiotic prescriptions. METHODS AND ANALYSIS: The PLUS-AP trial is an ongoing phase III, single-centre, blinded, parallel-group randomised controlled superiority trial conducted at a tertiary hospital in Beirut, Lebanon. Children aged 3 months to 18 years hospitalised with LRTI are randomly assigned (1:1) to LUS-guided management or to standard care with a sham lung ultrasound. In the intervention group, LUS is performed within 24 hours of admission and repeated around 48 hours later or before discharge, and the findings are shared with the treating team to inform management. The control group receives standard clinical evaluation, including chest X-ray as indicated, plus a non-diagnostic sham lung ultrasound. The primary outcome is antibiotic prescription at hospital discharge. Secondary outcomes are hospital length of stay; intensive care unit admission, chest tube insertion, mortality, hospital readmission, frequency of chest radiography performance and antibiotic use for LRTIs, all assessed within 4 weeks after enrolment. A total of 176 participants (88 per arm) will provide adequate power to detect a clinically important reduction in antibiotic prescribing, and analyses will follow the intention-to-treat principle with one planned interim analysis at 50% recruitment. ETHICS AND DISSEMINATION: The study protocol has been approved by the Institutional Review Board at the American University of Beirut (BIO-2024-0304). Written informed consent (and assent, when applicable) will be obtained for all participants. A Data and Safety Monitoring Committee will oversee patient safety and review interim results. Results will be disseminated through peer-reviewed publications, scientific conferences and targeted outreach to clinical and public health stakeholders to facilitate translation of the findings into routine practice. TRIAL REGISTRATION NUMBER: NCT06876766.