Table 1 Description and evidence base for different interventions A-C implemented at UCLH ED over the study period with timeline given in Fig 1

Targeting the influx of patients

Interventions A:

New triage setting with co-located GP and presence of senior doctor at UCLH ED

(February 2018)

Input stream

There is some evidence that changes to triage such as co-locating GPs within triage, having a senior doctor at triage or having rapid assessment pods within triage, can be effective in redirecting the flux of incoming patients and lead to reduced ED waiting time [16, 17, 25, 27,28,29,30,31].

Reducing pressure upon available patients’ bed

Interventions B

(October 2017)

Stream B1: Expansion of emergency floor

Stream B2:: Same day emergency clinic

Stream B3: Medical EAU

Throughput stream

Output stream

Output stream

There is some evidence that increasing bed numbers within ED can reduce ED waiting time [32,33,34].

There is some evidence that having the option to redirect patients arriving at triage to primary care, via same day emergency clinic may reduce overall ED waiting time [11, 25].

There is some evidence that presence of acute medical units within EDs can reduce ED waiting times [35,36,37].

Improving internal processes to increase outflow

Interventions C:

(April 2019)

Facilitation the workup of patients to include three streams: optimisation of workforce, clinical pathway and full digitisation of ED

Throughput streams

There is some evidence that interventions including improving specialty in-reach to ED or GPs working within the ED [11, 16, 31] or boarding patients [38] or digitization of the records within the Electronic Health Records (EHRs) database [39] can reduce ED overcrowding.