The effect of focused lung ultrasound on antibiotic prescribing in patients with acute lower respiratory tract infections in Danish general practice (PLUS-FLUS): a pragmatic, randomised controlled, post-market trial.

Background: Antimicrobial resistance is a growing global concern. Antibiotic use is the main driver and rational use is essential. General practitioners (GPs) prescribe most antibiotics for patients with acute lower respiratory tract infections (LRTI). This trial assessed whether focused lung ultrasound (FLUS) added to usual care in general practice could reduce antibiotic prescribing at the index consultation. Methods: In this pragmatic, randomised, post-market, superiority trial, adults presenting with acute cough and at least one other symptom of acute LRTI, in whom the GP suspected pneumonia, were invited to participate. 34 GPs across 28 Danish office-based general practice clinics recruited participants. Patients were randomly assigned 1:1, stratified by GP, to receive either usual care (controls), reflecting current standard examination and care, or usual care supplemented with FLUS. The primary outcome was the proportion and relative risk (RR) of patients having antibiotics prescribed at the index consultation. Outcome assessors were blinded to group allocation. All patients were included in the intention-to-treat analyses. The trial was registered at ClinicalTrials.gov (NCT06210282). Findings: Between November 1, 2023, and July 10, 2024, 390 patients were enrolled and analysed; 192 were assigned to the FLUS group. In the usual care group (n = 198), 81 patients (41%) were prescribed antibiotics at the index consultation compared with 69 (36%) in the FLUS group (n = 192; RR 0·88, 95% CI: 0·68-1·14). No evidence of harm was identified with the addition of FLUS to usual care. Interpretation: Addition of FLUS did not lead to a 15% or larger reduction in antibiotic prescribing at the index consultation. Routine implementation of FLUS in this patient population is not supported by the findings. However, no evidence of harm was observed with the addition of FLUS. Funding: The Health Foundation, The Foundation for General Practice, The Lung Association's Research Fund, and regional committees for Quality and Education.