The Short Long Antibiotic Course for Pleural Infection Management (SLIM) randomised controlled open-label trial.

Introduction: Based on expert opinion, the length of antibiotic treatment for pleural infection in adults is typically recommended to be a minimum of 4 weeks. This clinical trial aimed to assess whether shorter antibiotic courses lead to more treatment failures than standard longer courses.

Methods: In an open-label randomised controlled trial, adult patients with pleural infection who were medically treated and stabilised within 14 days of admission were randomised to either a short antibiotic course (total course 14-21 days) or a long antibiotic course (total course 28-42 days). Patients were excluded if their baseline RAPID score was >4 (high-risk category). The primary outcome was the incidence of treatment failure by 6 weeks post-admission. Secondary outcomes were total length of antibiotic treatment, proportion of patients who resumed normal activity levels within 6 weeks post-admission, time from discharge to resuming normal activity levels and incidence of antibiotic-related adverse reactions.

Results: Between September 2020 and October 2021, 50 patients (mean±sd age 46±13.7 years; 35 (70%) males) were recruited to the trial and randomly assigned to the short course group (n=25) or the long course group (n=25), with outcome data available for 24 patients in each study group. Treatment failure occurred in four (16.7%) patients in the short course group and three (12.5%) patients in the long course group. In the intention-to-treat analysis the OR for treatment failure in the long course group was 0.714 (95% CI 0.142-3.600; p=0.683). The median (interquartile range) duration of antibiotic treatment in the short course group was 20.5 (18-22.5) days compared with 34.5 (32-38) days in the long course group (p<0.001). There were no statistically significant differences in the other outcomes.

Conclusions: In medically treated adult patients with pleural infection a long course of antimicrobial therapy did not lead to fewer treatment failures compared with a shorter course. These findings need to be confirmed in a larger multicentre trial.