Short versus long-course antibiotic therapy for pyogenic liver abscess: an emulated target trial

The optimal treatment duration for pyogenic liver abscess (PLA) is still a matter of debate, with no comparative study to date. This study aimed to compare short and long treatment duration in hospitalized adult patients with PLA.

We retrospectively included patients with PLA from 2010 to 2022. Exposure was defined as a short (≤30 days) or long (>30 days) antibiotic regimen. We applied the target trial framework with cloning, censoring, and weighting. The primary outcome was the difference in relapse-free survival 90 days after antibiotic initiation. We defined a noninferiority margin of 10%.

Of 429 patients with PLA, 259 had a short and 170 a long-observed treatment duration. A total of 118 events were observed. The weighted risk difference (RD) in relapse-free survival between long and short treatment arm was -0.4% (95% CI: -5.9 to 4.9%), meeting the noninferiority margin. In undrained patients, the RD was -5.0% (95% CI: -15 to 5.7%), while among drained patients, the RD was 4.6% (95% CI: -4.4 to 13.5 %) in favour of short duration, achieving statistical significance for noninferiority for drained patients only. For overall survival, the weighted RD was -1.1% (95% CI: -5.9 to 3.4%), and for relapse, -0.2% (95% CI: -7.0 to 6.3%).

In our study, an antibiotic course of ≤30 days did meet the noninferiority threshold of 10% at 90 days compared with longer durations for relapse-free survival. Noninferiority was also met in the subgroup of drained patients but not in undrained patients.