Antibiotic stewardship in suspected neutropenic fever (ASTERIC trial): a multicentre, type 1 hybrid effectiveness-implementation, stepped-wedge, randomised controlled trial study protocol.

introductionNeutropenic fever (NF) has a crude mortality rate of 3-18%. International guidelines recommend that all patients with NF receive ultrabroad-spectrum antibiotics (UBSAs) within 1 hour of emergency department (ED) registration. However, over 70% patients presenting to hospital with suspected NF (sNF) cannot access absolute neutrophil count (ANC) result within 1 hour, do not have NF and do not require UBSAs. In ED and hospitalised patients with sNF, we hypothesise that the ASTERIC protocol effectively and safely reduces the use of UBSAs compared with standard care alone. METHODS AND ANALYSIS: This pragmatic, parallel, multicentre, type 1, hybrid effectiveness-implementation, stepped-wedge, before-and-after, cluster randomised controlled trial aims to evaluate whether antibiotic prescribing can be safely reduced through implementing a multifaceted antibiotic stewardship intervention (ASTERIC) in adult patients with sNF presenting to EDs. The sNF was defined as a fever with a single oral temperature of ≥38.3°C (101°F) within 24 hours before ED registration or a temperature of ≥38.0°C (100.4°F) sustained over a 1-hour period, following last chemotherapy or targeted therapy within 6 weeks for any solid tumour, or in any period following therapies against leucaemia, lymphoma, myelodysplastic syndrome, aplastic anaemia, multiple myeloma or recipient of HSCT. The study will involve eight hospitals in Hong Kong with variable baseline practice. We will include 704 adult patients (352 patients in pre-implementation and post-implementation periods, respectively) with sNF (tympanic temperature ≥38.3°C) and 48 staff participants (6 staff participants in each hospital). Healthcare professionals will receive a multifaceted stewardship intervention consisting of risk assessment tools, fast-track ANCs, a decision tool for patient management and antibiotic use, supported by an educational package and staff interaction programmes (ASTERIC protocol). Patients' blood ANC, and cancer therapy and chronic illness therapy scores will be measured. The RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) and Proctor conceptual frameworks will be followed for evaluation of implementation. The main outcome measures are the mean total dose of UBSAs prescribed in 7 days and serious adverse events at 30 days. Data analysis will incorporate intention-to-treat, per-protocol and as-treated analyses for service outcomes (effectiveness, safety, quality of life assessments and cost-effectiveness) and mixed methods for implementation outcomes, informed by the Theoretical Domains Framework. We expect that the study results will inform health policy with improvement in hospital services in treating stable sNF, evidenced by improved safe antibiotic stewardship, early antibiotic de-escalation and reduced costs and length of stay. ETHICS AND DISSEMINATION: The institutional review boards of all study sites approved this study. This study will establish the ASTERIC protocol safely improves antibiotic stewardship and clinical management in adult patients with sNF. We will disseminate the findings through peer-reviewed publications, conference presentations and educational activities. All patients with sNF will be influenced by the new protocol which is agreed at hospital level. Randomisation is at hospital level, not patient level. Patient consent is sought for follow-up and data access, not for treatment. Staff consent is sought for interviewing. TRIAL REGISTRATION NUMBER: NCT06794320.