Objectives Patient flow and crowding are two major issues in ED service improvement. A substantial amount of literature exists on the interventions to improve patient flow and crowding, making it difficult for policymakers, managers and clinicians to be familiar with all the available literature and identify which interventions are supported by the evidence. This umbrella review provides a comprehensive analysis of the evidence from existing quantitative systematic reviews on the interventions that improve patient flow in EDs.

Methods An umbrella review of systematic reviews published between 2000 and 2017 was undertaken. Included studies were systematic reviews and meta-analyses of quantitative primary studies assessing an intervention that aimed to improve ED throughput.

Results The search strategy yielded 623 articles of which 13 were included in the umbrella review. The publication dates of the systematic reviews ranged from 2006 to 2016. The 13 systematic reviews evaluated 26 interventions: full capacity protocols, computerised provider order entry, scribes, streaming, fast track and triage. Interventions with similar characteristics were grouped together to produce the following categories: diagnostic services, assessment/short stay units, nurse-directed interventions, physician-directed interventions, administrative/organisational and miscellaneous. The statistical evidence from 14 primary randomised controlled trials (RCTs) was evaluated to determine if correlation or clustering of observations was considered. Only the fast track intervention had moderate evidence to support its use but the RCTs that assessed the intervention did not use statistical tests that considered correlation.

Conclusions Overall, the evidence supporting the interventions to improve patient flow is weak. Only the fast track intervention had moderate evidence to support its use but correlation/clustering was not taken into consideration in the RCTs examining the intervention. Failure to consider the correlation of the data in the primary studies could result in erroneous conclusions of effectiveness.