Intravenous ceftriaxone at home versus intravenous flucloxacillin in hospital for children with cellulitis: a cost-effectiveness analysis

Background: Outpatient parenteral antibiotic therapy after hospital admission is increasingly popular, but its use to avoid admission to hospital altogether by treating patients wholly as outpatients remains uncommon in children. One reason for the low use of treatment at home is the scarcity of evidence of its cost-effectiveness. In this planned follow-up analysis of the Cellulitis at Home or Inpatient in Children from the Emergency Department (CHOICE) trial, we aimed to assess the cost-effectiveness of an admission avoidance pathway, in which children were treated at home, compared with standard hospital care for the intravenous treatment of moderate or severe cellulitis.

Methods: We did a cost-effectiveness analysis to compare home treatment with intravenous ceftriaxone versus hospital treatment with intravenous flucloxacillin in children aged 6 months to 18 years who had presented to the emergency department at The Royal Children's Hospital, Melbourne, VIC, Australia, with moderate or severe uncomplicated cellulitis. We included costs from two sources: institutional costs at a patient level and expenses incurred by families. We measured effectiveness with quality-adjusted life years (QALYs), which we derived from the Child Health Utility 9D questionnaire, and a clinical outcome of treatment failure, which was the primary outcome of the CHOICE trial. We planned to calculate the incremental cost-effectiveness ratio, defined as the difference between groups in total cost divided by the difference between groups in effectiveness. The CHOICE trial is registered at ClinicalTrials.gov, number NCT02334124.

Findings: We included 180 children who comprised the per-protocol population in the CHOICE trial: 89 children in the home group and 91 children in the hospital group. The institutional cost per patient per episode was significantly lower in the home group than in the hospital group (AUS$1965 vs $3775; p<0·0001). The mean cost incurred per family was $182 for the home group and $593 for the hospital group (p<0·0001). Both measures of effectiveness were significantly better in the home group than in the hospital group: QALYs were 0·005 for the home group versus 0·004 for the hospital group (p<0·0001), and treatment failure occurred in one (1%) patient in the home group versus seven (8%) patients in the hospital group (risk difference -6·5%, 95% CI -12·4 to -0·7; p=0·029). Calculating the incremental cost-effectiveness ratio was thus deemed redundant.

Interpretation: Treatment at home was less costly and more effective than standard hospital care for children with moderate or severe cellulitis. These findings support development of this admission avoidance pathway in hospitals.

Funding: The Royal Children's Hospital Foundation, Murdoch Children's Research Institute.