Seven days or less of systemic antibiotics was noninferior to four weeks when local antibiotics were used

Design

Multicentre, open-label, randomised noninferiority trial; blinded end-point committee

Population

500 adults after surgery for orthopaedic infection with a local-antibiotic carrier (475 in the primary analysis)

Primary outcome

Definite treatment failure by 12 months

Effect

11.1% (short) vs 14.1% (long); risk difference -3.0 percentage points (95% CI -9.0 to 3.0)

SOLARIO was a multicentre, open-label, noninferiority trial in adults who had surgery for orthopaedic infection and received an implanted local-antibiotic carrier. A total of 500 were randomised 1:1 to a short (7 days or less) or long (4 weeks or more) course of postoperative systemic antibiotics. A clinical end-point committee unaware of group assignment judged the primary outcome, definite treatment failure by 12 months.

Failure occurred in 34 of 241 patients (14.1%) in the long-course group and 26 of 234 (11.1%) in the short-course group (risk difference -3.0 percentage points, 95% CI -9.0 to 3.0). The upper bound lies inside the 10-point margin, and per-protocol and wider-population analyses agreed. By week 6, symptoms that could be related to treatment had occurred in 45.2% of the long-course group and 17.2% of the short-course group.

The finding applies to patients who had surgery and a local-antibiotic carrier; it does not show that a short course suffices when no local antibiotic is placed. The margin of 10 points is wide, and the upper limit of the interval (3.0) could still matter to an individual patient. Local-antibiotic carriers are not available everywhere.

• Consider a shorter systemic course after orthopaedic infection surgery only where a local-antibiotic carrier has been placed.
• Failure by 12 months was 11.1% with a short course and 14.1% with a long one.
• Treatment-related symptoms by week 6 were 17.2% with the short course against 45.2% with the long one.
• Agree the plan with the surgical team and microbiologist; this trial does not cover cases without a carrier.

Why it matters

It challenges the assumption that bone and joint infection always needs weeks of systemic therapy.

Don't overread it

All patients had a local-antibiotic carrier, and the trial was open-label, so it does not support short courses without local antibiotics.

The statistics, in plain English

Noninferiority means the short course was not worse than the long one by more than 10 percentage points. The interval of -9.0 to 3.0 stays below that limit, but it does not exclude a worse outcome of up to 3 percentage points with the long course or a similar difference the other way.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.