A procalcitonin-based rule cut antibiotics by a third without cost

Design

open cluster randomised clinical trial across 25 European paediatric emergency departments, stepped adoption over 3 years, intention-to-treat

Population

4,882 children aged 6 days to 36 months with acute fever without source; median age 3 months; serious bacterial infection in 15.7%

Primary outcome

antibiotic exposure within 15 days

Effect

26.2% vs 38.0% (OR 0.57, 95% CI 0.43-0.75, p<0.001); morbidity and mortality OR 0.83 (0.57-1.22)

Twenty-five European paediatric emergency departments ran an open cluster randomised trial in children aged 6 days to 36 months with fever without source. In the first year all centres used usual care; in the second, half adopted a decision rule combining age, clinical symptoms, urinalysis and point-of-care procalcitonin; in the third, all adopted it. The analysis compares 2,440 children under usual care with 2,442 under the rule.

This was not a low-risk population: serious bacterial infection occurred in 15.7% and invasive bacterial infection in 1.4%, with a median age of three months. Antibiotic exposure within 15 days fell from 38.0% to 26.2% (OR 0.57, 95% CI 0.43 to 0.75, p<0.001). Combined morbidity and mortality at day 15 did not differ (OR 0.83, 0.57 to 1.22).

The operative component is the point-of-care procalcitonin — a result available during the consultation rather than after the child has gone home or been admitted. That is what allows a rule to change the prescribing decision rather than to audit it afterwards. Before adopting this, the question for a unit is whether it can deliver procalcitonin at the bedside within the consultation; a send-away assay reproduces the cost of the test without the benefit.

• Check whether your department can deliver procalcitonin within the consultation before adopting a rule that depends on it
• The rule combines age, symptoms, urinalysis and procalcitonin — procalcitonin alone is not the intervention
• Baseline serious bacterial infection here was 15.7%; a lower-prevalence population will behave differently
• Safety was assessed at 15 days in 4,882 children — reassuring for common harms, not for rare ones
• Build in the safety-netting advice the trial's centres used; a rule that reduces prescribing depends on the return pathway working

Why it matters

It shows a decision rule can remove a third of antibiotic prescriptions in the population clinicians are least willing to under-treat.

Don't overread it

The trial was open and cluster-randomised across three sequential years; secular change in prescribing over 2018-2021 is not fully separable from the intervention.

The statistics, in plain English

An odds ratio of 0.57 corresponds to 11.8 fewer children in every hundred receiving antibiotics, which is the number to plan around. The safety comparison (OR 0.83, 0.57 to 1.22) includes 1.0, so the trial found no signal of harm — but with an invasive bacterial infection rate of 1.4%, it could not have detected a small increase in the rarest and most serious outcomes.

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