Patient and economic impact of implementing a paediatric sepsis pathway in emergency departments in Queensland, Australia
This study was a population-based multi-site, data-driven simulation model and cost–benefit analysis of acute service utilisation before and after the implementation of an ED PSP. The study was approved by research ethics and governance, including a waiver of individual consent (Children’s Health Queensland HREC/18/QRCH/167) as well as state Public Health Act approval. No identifying information was used, and all research was conducted in accordance with relevant guidelines and regulations. Details of the Queensland Sepsis Collaborative18 and the PSP17 have been previously described. The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist19 was used to report outcomes (Supplement 2).
The PSP was introduced as a paper-based clinical decision support tool, based on the Surviving Sepsis Campaign and comprised of: systematic screening of paediatric patients to facilitate recognition of possible sepsis; appropriate escalation using decision trees; a protocolized treatment bundle with guides for antibiotic prescription and administration; and a parental information leaflet17,18. The purpose of the PSP was to assist ED physicians to recognize sepsis earlier in the disease process, enabling earlier treatment and better compliance with the sepsis treatment bundle, leading to improved clinical outcomes. Emergency physicians were trained to use the PSP by a dedicated paediatric sepsis clinical nurse consultant. A detailed description of the PSP version 1, used during the study period, can be obtained by contacting the corresponding author, although this has since been superseded by updated versions which can be obtained at: https://clinicalexcellence.qld.gov.au/priority-areas/safety-and-quality/sepsis/sepsis-resources/paediatric-sepsis-pathways.
Study participation was voluntary and restricted to EDs capable of advanced resuscitation, stabilisation and rapid transfer20. Further description of the Queensland hospital capability framework is provided in Supplement 3. Twenty-one Queensland hospitals were initially eligible for involvement, and 16 chose to participate. Participating sites had nominated sepsis teams responsible for leading implementation, supported by central quality improvement advisors from the sepsis collaborative.
Setting and population
Queensland is the second largest state in Australia geographically and has an estimated population of 5.2 million (June 2020). It has the greatest population dispersion of any Australian state, over a geographical area larger than Alaska. The proportion of children (0–14 years) in the state has been relatively steady over the last 5 years at 19.3%, reflecting a paediatric population of approximately one million21. Paediatric care in Queensland is centralized, with quaternary care occurring in a single children’s hospital in Brisbane. Children requiring escalation of care are transported to more specialized centres, with the mode of travel (road, rotary or fixed wing transport) dictated by transport distance.
Inpatient episodes for all patients aged under 18, admitted via ED with an ICD-10 coded diagnosis of sepsis across Queensland, were compared before and after the intervention. Patients with ward-acquired sepsis codes were excluded. Sepsis coding is provided in Supplement 3. Three hospitals piloted the PSP before it was introduced at a further 13 sites, including the state children’s hospital. These 16 sites were compared to 32 hospitals that did not implement the PSP. Sites were categorized into:
PSP-CH: The only dedicated children’s hospital (CH) in the state; implemented the PSP in the ED. This is the paediatric tertiary/quaternary hospital in Queensland and is the primary transfer destination for paediatric patients requiring a significant escalation in care.
PSP-mixed: Two dedicated paediatric EDs and 13 EDs treating a mixed population of adults and children that implemented the PSP. Does not include PSP-CH.
Non-PSP: EDs of 32 acute care hospitals that did not implement the PSP. These include 24 smaller regional facilities without ICU capability and eight tertiary facilities with ICU capability.
Figure 1 displays the likely patient pathways for PSP-mixed and non-PSP sites (panel A) and the PSP-CH (panel B). Patients were assumed to be non-palliative, meaning that mortality was only likely in ICU. In Queensland, the transfer process typically occurs by local referral from lower capability centres to an intensive care specialist through Retrieval Services Queensland. The intensivist provides advice, initiates triage with logistic support by Retrieval Services Queensland, and facilitates transfer to a higher capability tertiary care centre if required. This transfer is then conducted by paediatric intensive care, a designated adult, or paramedic team depending on clinical need.
The pre-implementation period was from September 2015 to August 2017 for one PSP-mixed pilot site and from July 2016 to June 2018 for all remaining sites, including two additional PSP-mixed pilot sites and all non-PSP sites. A wash-out period was applied while staff were trained in the PSP and supporting infrastructure put into place. This was between September 2017 and July 2018 for the first pilot site, from June 2018 to July 2018 for the remaining two pilot sites, and from June 2018 to January 2019 for the remaining PSP and non-PSP sites.
The PSP implementation period was from July 2018 to July 2020 for the three PSP-mixed pilot sites. For the remaining sites, including PSP-CH and non-PSP sites, the PSP implementation period was from January 2019 to December 2020. A schedule is provided in Supplement 4. The wash-out period was also applied to non-PSP sites as a counterfactual condition to determine state-wide trends in healthcare utilisation independent of the program.
This study used available data that are routinely collected in the Queensland Hospital Admitted Patient Data Collection (QHAPDC). Data from QHAPDC were available in aggregate form as summary statistics by pre-intervention, wash-out, and intervention periods for each group, with 24 months of pre- and post-implementation data for each site. Utilisation data included: non-ICU LOS; ICU LOS; ICU admission rate; and the transfer out rate. Non-ICU LOS refers to any amount of time during admission not spent in the ICU.
The primary study outcome was hospital length of stay in bed days, separated into ICU and non-ICU bed days. The value of ICU bed days selected was $5381 (SD $1423), derived from previous research22 and updated to 2021 values using a 3% discount rate, standard for economic evaluations in developed countries such as the USA and Australia23,24. The value of ward bed days could not be derived from the literature. We solicited the cost of a paediatric bed day from Queensland Health and received a mean value plus overheads of $1512 per day based on representative general wards from the hospital-based corporate information system. Due to the uncertainty around this figure, we applied the same level of uncertainty as in the ICU day valuation, which was 26.4% ($400). Interhospital transfer costs were not available, but the transfer rate was analysed for context.
Statistical and economic analysis
Probabilistic sensitivity analysis (PSA) is a method of quantifying uncertainty in model input parameters using Monte Carlo simulation methods25,26. As patient-level data were not accessible to determine whether changes were due to sampling bias, simulation was applied to estimate uncertainty intervals. Summary statistics were used to create appropriate prior distributions, from which 10,000 samples were drawn to compare patient outcomes before and after implementation across PSP and non-PSP sites25.
To estimate statewide changes following implementation, our null hypothesis was that rates would remain unchanged. Expected results were calculated by multiplying post-implementation sample sizes by pre-implementation utilisation. Expected results were then subtracted from observed results to estimate changes associated with the PSP. To determine the counterfactual, or expected change at PSP sites in the program’s absence, difference-in-difference calculations were applied. The percentage change for non-PSP sites was subtracted from the change for PSP sites to account for general care trends across Queensland.
The costs of the PSP were calculated by summarizing total labour costs for clinical, administrative, and support staff to develop and deliver the program from 2017 to 2021. Staff time allocated to project implementation was tabulated for both in-kind and budgeted activities. Staff time was then multiplied by salary rates calculated pro-rata based on Queensland Health pay scales27 and converted to 2021 values. A detailed summary of all PSP costs is contained in Supplement 5.