Article Text

The role of a rapid assessment zone/pod on reducing overcrowding in emergency departments: a systematic review
1. Michael J Bullard1,
2. Cristina Villa-Roel1,2,
3. Xiaoyan Guo1,
4. Brian R Holroyd1,
5. Grant Innes3,
6. Michael J Schull4,
7. Benjamin Vandermeer5,
8. Maria Ospina2,6,
9. Brian H Rowe1,2,5
1. 1Department of Emergency Medicine, University of Alberta, Edmonton, Alberta, Canada
2. 2School of Public Health, University of Alberta, Edmonton, Alberta, Canada
3. 3Department of Emergency Medicine, University of Calgary, Calgary, Alberta, Canada
4. 4Department of Emergency Medicine, University of Toronto, Toronto, Ontario, Canada
5. 5Evidence-Based Practice Centre, University of Alberta, Edmonton, Alberta, Canada
6. 6Institute of Health Economics, Edmonton, Alberta, Canada
1. Correspondence to Dr Brian H Rowe, Department of Emergency Medicine, University of Alberta, 1G1.42 Walter C Mackenzie Centre, 8440-112 Street, Edmonton, Alberta T6G 2B7, Canada; brian.rowe{at}ualberta.ca

## Abstract

Objective To evaluate the effectiveness of a rapid assessment zone (RAZ) to mitigate emergency department (ED) overcrowding.

Methods Electronic databases, controlled trial registries, conference proceedings, study references, experts in the field and correspondence with authors were used to identify potentially relevant studies. Intervention studies, in which a RAZ was used to influence length of stay, physician initial assessment and patients left without being seen, were included. Mean differences were calculated and reported with corresponding 95% CIs; individual statistics are presented as RR with associated 95% CI.

Results From 14 446 potentially relevant studies, four studies were included in the review. The quality of one study was appraised as moderately high; others were rated as weak. Two studies showed that a RAZ was associated with a reduction of 20 min (95% CI: −47.2 to 7.2) in the ED length of stay; in one non-randomised clinical trial (RCT), a 192 min reduction was reported (95% CI: −211.6 to −172.4). Physician initial assessment showed a reduction of 8.0 min; 95% CI: −13.8 to −2.2 in the RCT and a reduction of 33 min (95% CI: −42.3 to −23.6) and 18 min (95% CI: −22.2 to −13.8) respectively were found in two non-RCTs. There was a reduction in the risk of patient leaving without being seen (RCT: RR=0.93, 95% CI: 0.77 to 1.12; non-RCT: RR =0.68, 95% CI: 0.63 to 0.73).

Conclusions Although the results are consistent, and low acuity patients seem to benefit the most from a RAZ, the available evidence to support its implementation is limited.

• Emergency medicine
• intervention studies
• overcrowding
• review
• nursing
• emergency departments
• management
• emergency department management
• emergency ambulance systems
• effectiveness

## Introduction

Emergency department (ED) overcrowding is defined as ‘a situation in which the demand for emergency services exceeds the ability to provide quality care within a reasonable time’.1 Many high volume, urban and specialty EDs suffer from overcrowding, leading to a myriad of negative effects on ED quality of care, staff/patient satisfaction and other patient-related outcomes.2 3 Previous studies suggested that a significant proportion of morbidity and mortality cases could be attributed to delays in ED diagnosis and treatment.4 As ED overcrowding has become a ubiquitous challenge facing emergency care providers across the globe, many studies have been designed to explore the causes and develop interventions to solve this problem. The input-throughput-output conceptual model represents a comprehensive view of the multidimensional nature of the ED overcrowding; this model outlines a variety of operational processes that may be optimised to mitigate ED congestion.5 6

Recently, rapid assessment zones/pods (RAZ/RAP) have been instituted as novel interventions to target the throughput component of the overcrowding model, the interval from ED patient arrival (triage or registration time) to disposition (hospital admission or discharge home).7 RAZ/RAP units have been variably described in the scientific literature. RAZ/RAP are generally existing ED spaces adapted for clinician assessment and procedures; in such settings, patients have their investigations started, wait for results and/or receive treatment in a chair or on a stretcher. In principle, this intervention attempts to improve access to care for some of the more complex acute ambulatory emergency patients currently being forced to wait for a stretcher space. Their assessment and therapeutic requirements exceed that of the typical fast-track patient; however, ideally they are not severely ill or injured, and can receive their investigations/therapy in a chair and require limited observation. Streaming appropriate patients to the RAZ/RAP rather than a stretcher facilitates prompt decision-making, encourages more rapid patient turnover and has the potential to mitigate ED overcrowding.

While previous efforts have been made to summarise the available evidence on the benefits of interventions designed to modify throughput factors, no systematic review has assessed the specific contribution of the RAZ/RAP to mitigate ED overcrowding.8 This information will provide healthcare decision makers and clinicians with an opportunity to understand the characteristics and value of RAZ/RAP. Moreover, such evidence has the potential to guide policy-makers and ED administrators in the most efficient use of healthcare resources.

The objective of this study was to summarise the available evidence assessing the impact of RAZ/RAP to mitigate ED overcrowding, and to evaluate the quality of the current research.

## Methods

### Study protocol

An a priori study protocol was used to define the search strategy, set the study selection criteria, outline quality assessment and data extraction procedures, and propose the analytical approaches to study data.

### Search strategy

A comprehensive literature search was conducted in seven biomedical electronic databases: Medline, Embase, EMB Reviews—Cochrane Central Register of Controlled Trials, HealthSTAR, Science Citation Index Expanded, Dissertation Abstracts and ABI/INFORM Global, using keywords and controlled vocabulary to identify relevant literature (see appendix 1 for details). Clinical trial registries (ClinicalTrials.gov, controlled-trials.com) and Google Scholar web searches were also explored. The search strategy developed for the Canadian Agency for Drugs and Technologies in Health (CADTH) report Interventions to Reduce Overcrowding in Emergency Departments was updated for this study.8 The original CADTH report involved literature searches from 1966 to December 2005, this study searched for citations between October 2004 and May 2009, both without restrictions on language or publication status. The overlapping was necessary to ensure that all the new literature indexed after the CADTH report was completed would be considered for inclusion.

Hand-searches were performed to identify abstracts presented to the following major scientific conferences between October 2004 and May 2009: the Canadian Association of Emergency Physicians, the American College of Emergency Physicians, the Society of Academic Emergency Medicine, the College of Emergency Medicine in the UK and the Australasian College for Emergency Medicine. In addition, the references of identified articles were manually searched. Primary authors and experts in the field were contacted to identify additional published, unpublished or ongoing studies. The search results from the CADTH report were merged with that of the updated searches, resulting in a comprehensive search strategy to identify potentially relevant studies published from 1966 to May 2009.

### Study selection

Eligible studies were primary research that assessed the impact of a RAZ/RAP to mitigate the effect of overcrowding in EDs serving adult (17 years or older) or mixed (ie, child and adult) populations. Studies with one of the following designs were included: paralleled or clustered group randomised controlled trials (RCTs/cRCTs), controlled clinical trials (CCT), prospective or retrospective analytical cohort studies, interrupted time series, case-control studies and before-after designs. We intentionally excluded articles in which the words ‘fast track’ were mentioned in their titles. Studies were required to report numeric data on at least one of the following outcomes: length of stay (LOS; time in min from patient arrival to departure from the ED), physician initial assessment (time in min from patient arrival to being seen by a doctor) and proportion of patients who left without being seen (LWBS). Non-primary research (eg, editorials, commentaries, letters, narrative reviews, technology reports and systematic reviews), studies conducted in paediatric EDs, multiple publications and studies comparing two levels of the same intervention were excluded.

Three reviewers (BR, MO, XG) independently screened titles and abstracts of studies identified by the literature search. The full-text versions of articles deemed potentially relevant as well as those that reported insufficient information to determine eligibility, were independently reviewed by two of four reviewers (BR, MO, CV, LW). Any disagreements were resolved by consensus. Non-English literature was translated by foreign language reviewers (SMH and DS). Studies that met all inclusion criteria were eligible for quality assessment and data extraction.

### Quality assessment

A standard quality-rating tool developed by the Effective Public Health Practice Project (EPHPP) was used to appraise the quality of the studies.9 This tool is based on guidelines set out by Mulrow et al and Jadad et al, and has accepted validity and reliability.10–12 The tool rating is based on six criteria: selection bias, study design, confounders, blinding, data collection methods, and withdrawals and dropouts. Each criterion is rated as ‘strong’, ‘moderate’ or ‘weak’ depending on information reported in the article. Once the ratings of characteristics are totalled, each study receives an overall assessment of strong, moderate or weak quality. Two of three assessors (BR, LW, XG) independently rated the quality of included studies and resolved discrepancies by consensus.

### Data extraction

Information regarding the study design and methods (eg, year, country, type of publication, study duration, number of participating centres, study design), intervention's characteristics and comparisons, and outcomes of interest were extracted using a pretested data extraction form. Finally, data on study conclusions, as reported by the authors of the primary studies was independently conducted by two of three reviewers (BR, LW, XG). Attempts were made to communicate with investigators for clarification or additional data.

### Data analysis

Characteristics of the included studies were summarised using descriptive statistics. Evidence tables were constructed to report information on each article's source, study design, study population, treatment groups and outcomes. Meta-analyses were originally planned as part of the data analysis to derive pooled estimates from individual studies; however, due to the small numbers of studies included, this was not feasible. Data of individual studies were presented as relative risk (RR) with 95% CIs for dichotomous outcomes and mean differences (MD) with 95% CI for continuous outcomes. For a study not reporting SD, values from a similar study were imputed.

Analyses were focused on ED LOS, physician initial assessment and proportion of LWBS. A p value of less than 0.05 was considered statistically significant. All data were entered into Review Manager V.5.0 software.

## Results

### Search results

The systematic search resulted in the identification of 14 446 potentially relevant citations, from which 3615 studies clearly addressed the topic of ED overcrowding. After screening the studies' titles and abstracts, 354 full manuscripts were retrieved for further examination. The application of the selection criteria to the 354 studies resulted in four studies included and 350 excluded from the review (figure 1). The complete list of references of excluded studies is available upon request.

Figure 1

Literature search and study selection flow.

### Study characteristics

Of the four included studies, one was a journal publication, one was a brief report and two were abstracts (table 1).7 13–15 Two studies (one RCT and one before-after study) were conducted in Canada, while one CCT and one before-after study were from New Zealand and Saudi Arabia, respectively. All were single-centre ED studies; however, important insight into the characteristics and delivery of these interventions were reported. For example, while some interventions were operational between 09:00 and 23:00 h; others were only implemented when the ED was gridlocked.13 15 RAZ/RAP were generally developed by co-opting existing treatment spaces as assessment and treatment areas rather than allowing patients to continuously occupy a stretcher.7 13–15 Some treatment spaces had their stretchers replaced by chairs for patients to rest after they had first been assessed on a stretcher. Suitability for the RAZ/RAP was considered independent of triage level; however, it tended to include subjects who were ambulatory, in whom disposition was readily apparent, where interventions required were quickly undertaken, and in whom lengthy investigations or close observation were not required.

Table 1

Descriptive characteristics of studies included in the review

Based on the EPHPP tool, the overall quality of one study was rated as moderate; the other three studies were appraised as weak (figure 2).7 13–15

Figure 2

Frequency of the six components of the EPHPP9 tool and Global* ratings.

### Primary outcomes

#### Emergency department length of stay

Two studies reported outcome data on ED LOS.13 14 One RCT showed a non-significant reduction in the ED LOS associated with a RAZ/RAP intervention (MD=−20.0 min; 95% CI: −47.2 to 7.2),13 while a significant reduction was observed in a before-after study (MD=−192.0 min; 95% CI: −211.6 to −172.4)14 (figure 3). Two studies provided subgroup analysis for patients with triage and acuity scores of two to five.7 13 Both studies used five-level scale ranges from resuscitation (1) to less urgent (5). One RCT failed to demonstrate a benefit from a RAZ/RAP intervention for patients with triage and acuity scores of five (MD=−34.0 min; 95% CI: −68.6 to 0.6)13 and one CCT showed a benefit for patients with triage acuity scores of five (MD=−20.0 min; 95% CI: −23.1 to −16.9).7

Figure 3

Impact of a Rapid Assessment Zone/Pod (RAZ/RAP) intervention on reducing emergency department length of stay (ED LOS), physician initial assessment and patients leaving without being seen (LWBS).

#### Physician initial assessment

Three studies reported outcome data on physician initial assessment,13–15 all reporting a significant reduction associated with a RAZ/RAP intervention (MD=−8.0 min (95% CI: −13.8 to−2.2) for the RCT;13 MD=−33.0 min (95% CI: −42.3 to −23.6) and MD =−18.0 min (95% CI: −22.21 to −13.8) for the before-after studies).14 15 Two studies assessed physician initial assessment in patients with triage acuity scores of two to five; the RCT found no benefit in patients with triage acuity scores of five (MD=−14.0 min; 95% CI: −33.5 to 5.5),13 whereas the CCT showed a benefit for patients with triage acuity scores of five (MD=−11.1 min; 95% CI: −12.4 to −9.8).7

### Secondary outcome

#### Left without being seen

Two studies reported data on LWBS.13 14 A statistically significant reduction in LWBS was associated with a RAZ/RAP intervention in a before-after study (RR=0.68; 95% CI: 0.63 to 0.73)14; however, the result was not statistically significant in the RCT (RR=0.93; 95% CI: 0.77 to 1.12).13

## Discussion

RAZ/RAP units are a promising option for improving throughput in overcrowded EDs. It is important to clarify that RAZ/RAP refers to ED areas where observation/examinations are completed in patients with ambulatory problems but no specific bed is assigned to them; this intervention differs from fast track areas (oriented to low severity cases), observation units (areas juxtaposed to or within the ED where patient observation/examinations are required prior to admission decisions; <24 h of ED LOS), medical admission units (areas juxtaposed to the ED where observation/examinations are completed on admitted patients before their transfer to the floor; 24–72 h of LOS). RAZ/RAP also differs from triage liaison physician interventions where physicians work with triage teams to expedite patient care.

To our knowledge, this is the first systematic review assessing the value of a RAZ/RAP in ED-based health practices. Using a comprehensive and exhaustive search strategy, however, only four studies that specifically evaluated the effects of the RAZ/RAP intervention on mitigating ED overcrowding were included in this systematic review. Surprisingly, only one study was an RCT and only two studies had been published. Overall, the quantity of research available upon which to make a decision on implementing RAZ/RAP units is limited. Moreover, the quality of that research suggests important weaknesses limiting the ability of this review to offer policy recommendations.

The RAZ/RAP intervention evaluated using non-RCT methodology was associated with a significant reduction in the ED LOS (∼3 h)14; a non-statistically, however, clinically significant reduction in the ED LOS (20 min) resulted from the only RCT included in this review.13 This remarkable difference of the effect size between the non-RCT and RCT may be attributable to confounding bias, intervention variability and selection bias.16 17 A previous systematic review revealed that failure to use random allocation and concealment of allocation were associated with larger or smaller estimates of effects than those that did.16 Another study further suggested that the effect of confounders in non-randomised studies may exceed the effect of the interventions (ie, creating a benefit that is not real or hiding the benefit that is real).18 Alternatively, the setting and interventions reported here are variable and perhaps RAZ/RAP works differently in different EDs due to factors such as patient acuity and complexity, attempts to optimise efficiency, admission rates, organisational culture, funding models (fee-for-service vs salary), and other confounders. When analysing patients by triage level, patients with triage acuity scores of five benefited the most from the RAZ/RAP intervention. This aligns with the principle of fast track interventions designed to expedite care of the less urgent patients. RAZ/RAP intervention was not specifically designed to address the issue of fast track patients; however, clearly, they have the ability to function as a fast track area as well. Finally, there was a slight reduction in the rate of LWBS patients after the initiation of the RAZ/RAP; however, only in non-RCT studies.

Based on the EPHPP tool, the overall quality of three included studies was weak and one was moderate. Of the four studies, three were non-RCTs. The fact that these study designs are vulnerable to confounding and more susceptible to bias could to some extent explain the low rating obtained.16 The type of literature may also account for this low rating; one was a journal publication, the other three were non-journal publications. One of the shortcomings of abstracts and brief reports is the word limit, which limits discussion of study design and characteristics. Further studies with high quality study methods and standardised outcome reporting are required to assess the effectiveness of this promising alternative to mitigate ED overcrowding.

The triggers, setup and implementation of RAZ/RAP reported in the included studies also varied. We intentionally excluded articles in which the words ‘fast track’ were mentioned in their titles; our approach was to include studies in which all triage level patients were placed in ED adjacent waiting areas while they were undergoing investigation and treated (patients not allowed to remain on a treatment stretcher). The heterogeneity among study interventions, populations, settings and study periods make the interpretation of the results difficult and limit their generalisability. Regardless of the characteristics of the intervention in the studies, the common feature was that investigators transformed existing spaces into RAZ/RAP, where patients were assessed and treated in a more rapid and ambulatory fashion.

Developing standardised protocols for RAZ/RAP will facilitate their implementation and provide a platform to compare results among centres. However, standardised protocols may be hampered by the variable demands of each specific clinical practice setting. Moreover, it is likely that RAZ/RAP units perform differently in different ED types. For example, in a tertiary care ED with complex, high acuity patients, RAZ/RAP units may not be as effective as overcrowded EDs with lower acuity patients. Therefore, additional efforts on the subgroup analysis of RAZ/RAP are warranted.

### Strengths and limitations

The following limitations should be acknowledged when interpreting the results of this review. First, a very small number of RAZ/RAP studies were found; included studies had variable research methodologies and poor reporting. Second, missing data was common in these studies; however, efforts to contact the investigators made possible the addition of some original data and appropriate imputation techniques were used to ensure valid inference.19 Due to insufficient data, anticipated subgroup comparisons and sensitivity analyses were not always possible; however, sub-group analyses by patients with triage acuity scores of two to five were completed. Third, despite our comprehensive and detailed search strategy, it is possible that some publication bias influenced our results. We did not test the detection of publication bias due to subjectivity linked to funnel plot interpretation when the number of studies included is small.20 Recent evidence suggests that publication bias is less pervasive in the ED literature; however, negative studies are less likely to be published and more likely to be excluded from a review of this nature.21 Fourth, there is no universal indicator of ED overcrowding and there are limitations associated with the use of surrogate markers. Despite this concern, we used pre-defined ED times (eg, LOS and physician initial assessment) and patient outcomes (eg, LWBS) as surrogate markers of crowding, as they are feasible and have shown face validity.22 Finally, selection bias is possible; however, all abstracts and manuscripts were screened by at least two independent reviewers using standardised eligibility criteria in an effort to decrease the likelihood of this bias.

### Conclusion

The effectiveness of RAZ/RAP interventions is derived from a small number of studies with variable research methodologies. Although the results appeared to suggest a positive effect, the available evidence to support its implementation is limited and weak. Additional efforts using higher quality methods and standardised reporting are required to assess the effectiveness of this promising alternative to mitigate ED overcrowding; cost evaluations are also required to determine the utility of this intervention.

## Acknowledgments

The authors would like to thank the corresponding authors: Drs Penciner and Ardagh for their responses to our request for additional data. The authors are grateful to Donna Ciliska and Donna Fitzpatrick-Lewis for their explanation on the EPHPP quality assessment tool and to Diana Satanovsky-Feldman and Siri Margrete Holm for their assistance in translation.

## Appendix 1 Exact search strings

 String terms 1 exp CROWDING/ 2 crowd$.ti,ab. 3 overcrowd$.ti,ab. 4 gridlock$.ti,ab. 5 “access block$”.ti,ab. 6 warehous$.ti,ab. 7 (“left without being seen” or “leave$ without being seen” or lwbs).ti,ab. 8 (ambulance$adj2 diver$).ti,ab. 9 “fast track$”.ti,ab. 10 (wait$ adj2 time$).ti,ab. 11 *Health Services Misuse/ 12 (misuse$ or overutili$).ti,ab. 13 ((nonurgent or non-urgent or inappropriate or nonacute) adj5 (patient$ or visit$or use$ or care or problem$or attend$)).ti,ab. 14 (“length of stay$” or los).mp. 15 (length adj2 stay$).ti,ab. 16 (lama or (leave$adj4 (“medical advice” or treatment$)) or (left adj4 (“medical advice” or treatment$))).ti,ab. 17 or/1-16 18 *emergency medical services/ or *emergency medical service communication systems/ or *emergency service, hospital/ or *trauma centers/ or *emergency services, psychiatric/ or *“transportation of patients”/ or *ambulances/ or *air ambulances/ or *triage/ 19 (triage$ or “emergency medical service$communication$ system$” or “trauma center$” or “trauma centre$” or “tranport$ adj2 patient$”).mp. 20 (emergenc$ adj2 (medical$or health or hospital$ or psychiatric) adj2 service$).mp. 21 ((“a and e” or “a & e” or a&e) adj1 (service$ or department$)).ti,ab. 22 ((emergenc$ or emerg or accident$or casualt$) adj2 (service$or department$ or room$or centre$ or center$or unit$)).ti,ab. 23 (“acute care” or “emergency care”).mp. 24 (emergicenter$or emergicentre$).mp. 25 (((prehospital or pre-hospital) adj2 emergenc$adj2 care$) or (“prehospital care” or “pre-hospital care”)).mp. 26 (emergenc$adj2 (outpatient$ or out-patient$) adj2 unit$).mp. 27 ((ems or ed or er) and emergenc$).mp. 28 (“observation unit$” or “observation area$” or “holding unit$” or “holding area$”).ti,ab. 29 “Canadian Triage and Acuity Scale”.mp. 30 ambulance$.ti,ab. 31 or/18-30 32 17 and 31
Table AI

MEDLINE®—Ovid version

 String terms 1 exp CROWDING/ 2 crowd$.ti,ab. 3 overcrowd$.ti,ab. 4 gridlock$.ti,ab. 5 “access block$”.ti,ab. 6 warehous$.ti,ab. 7 (“left without being seen” or “leave$ without being seen” or lwbs).ti,ab. 8 (ambulance$adj2 diver$).ti,ab. 9 “fast track$”.ti,ab. 10 (wait$ adj2 time$).ti,ab. 11 *Health Services Misuse/ 12 (misuse$ or overutili$).ti,ab. 13 ((nonurgent or non-urgent or inappropriate or nonacute) adj5 (patient$ or visit$or use$ or care or problem$or attend$)).ti,ab. 14 (“length of stay$” or los).mp. 15 (length adj2 stay$).ti,ab. 16 (lama or (leave$adj4 (“medical advice” or treatment$)) or (left adj4 (“medical advice” or treatment$))).ti,ab. 17 or/1-16 18 *emergency medical services/ or *emergency medical service communication systems/ or *emergency service, hospital/ or *trauma centers/ or *emergency services, psychiatric/ or *“transportation of patients”/ or *ambulances/ or *air ambulances/ or *triage/ 19 (triage$ or “emergency medical service$communication$ system$” or “trauma center$” or “trauma centre$” or “tranport$ adj2 patient$”).mp. 20 (emergenc$ adj2 (medical$or health or hospital$ or psychiatric) adj2 service$).mp. 21 ((“a and e” or “a & e” or a&e) adj1 (service$ or department$)).ti,ab. 22 ((emergenc$ or emerg or accident$or casualt$) adj2 (service$or department$ or room$or centre$ or center$or unit$)).ti,ab. 23 (“acute care” or “emergency care”).mp. 24 (emergicenter$or emergicentre$).mp. 25 (((prehospital or pre-hospital) adj2 emergenc$adj2 care$) or (“prehospital care” or “pre-hospital care”)).mp. 26 (emergenc$adj2 (outpatient$ or out-patient$) adj2 unit$).mp. 27 ((ems or ed or er) and emergenc$).mp. 28 (“observation unit$” or “observation area$” or “holding unit$” or “holding area$”).ti,ab. 29 “Canadian Triage and Acuity Scale”.mp. 30 ambulance$.ti,ab. 31 or/18-30 32 17 and 31
Table AII

EMBASE—Ovid version

 String terms 1 exp CROWDING/ 2 crowd$.ti,ab. 3 overcrowd$.ti,ab. 4 gridlock$.ti,ab. 5 “access block$”.ti,ab. 6 warehous$.ti,ab. 7 (“left without being seen” or “leave$ without being seen” or lwbs).ti,ab. 8 (ambulance$adj2 diver$).ti,ab. 9 “fast track$”.ti,ab. 10 (wait$ adj2 time$).ti,ab. 11 *Health Services Misuse/ 12 (misuse$ or overutili$).ti,ab. 13 ((nonurgent or non-urgent or inappropriate or nonacute) adj5 (patient$ or visit$or use$ or care or problem$or attend$)).ti,ab. 14 (“length of stay$” or los).mp. 15 (length adj2 stay$).ti,ab. 16 (lama or (leave$adj4 (“medical advice” or treatment$)) or (left adj4 (“medical advice” or treatment$))).ti,ab. 17 or/1-16 18 *emergency medical services/ or *emergency medical service communication systems/ or *emergency service, hospital/ or *trauma centers/ or *emergency services, psychiatric/ or *“transportation of patients”/ or *ambulances/ or *air ambulances/ or *triage/ 19 (triage$ or “emergency medical service$communication$ system$” or “trauma center$” or “trauma centre$” or “tranport$ adj2 patient$”).mp. 20 (emergenc$ adj2 (medical$or health or hospital$ or psychiatric) adj2 service$).mp. 21 ((“a and e” or “a & e” or a&e) adj1 (service$ or department$)).ti,ab. 22 ((emergenc$ or emerg or accident$or casualt$) adj2 (service$or department$ or room$or centre$ or center$or unit$)).ti,ab. 23 (“acute care” or “emergency care”).mp. 24 (emergicenter$or emergicentre$).mp. 25 (((prehospital or pre-hospital) adj2 emergenc$adj2 care$) or (“prehospital care” or “pre-hospital care”)).mp. 26 (emergenc$adj2 (outpatient$ or out-patient$) adj2 unit$).mp. 27 ((ems or ed or er) and emergenc$).mp. 28 (“observation unit$” or “observation area$” or “holding unit$” or “holding area$”).ti,ab. 29 “Canadian Triage and Acuity Scale”.mp. 30 ambulance$.ti,ab. 31 or/18–30 32 17 and 31
Table AIII

Central (EBM Reviews—Cochrane Central Register of Controlled Trials)—Ovid version

 String terms 1 exp CROWDING/ 2 crowd$.ti,ab. 3 overcrowd$.ti,ab. 4 gridlock$.ti,ab. 5 “access block$”.ti,ab. 6 warehous$.ti,ab. 7 (“left without being seen” or “leave$ without being seen” or lwbs).ti,ab. 8 (ambulance$adj2 diver$).ti,ab. 9 “fast track$”.ti,ab. 10 (wait$ adj2 time$).ti,ab. 11 *Health Services Misuse/ 12 (misuse$ or overutili$).ti,ab. 13 ((nonurgent or non-urgent or inappropriate or nonacute) adj5 (patient$ or visit$or use$ or care or problem$or attend$)).ti,ab. 14 (“length of stay$” or los).mp. 15 (length adj2 stay$).ti,ab. 16 (lama or (leave$adj4 (“medical advice” or treatment$)) or (left adj4 (“medical advice” or treatment$))).ti,ab. 17 or/1–16 18 *emergency medical services/ or *emergency medical service communication systems/ or *emergency service, hospital/ or *trauma centers/ or *emergency services, psychiatric/ or *“transportation of patients”/ or *ambulances/ or *air ambulances/ or *triage/ 19 (triage$ or “emergency medical service$communication$ system$” or “trauma center$” or “trauma centre$” or “tranport$ adj2 patient$”).mp. 20 (emergenc$ adj2 (medical$or health or hospital$ or psychiatric) adj2 service$).mp. 21 ((“a and e” or “a & e” or a&e) adj1 (service$ or department$)).ti,ab. 22 ((emergenc$ or emerg or accident$or casualt$) adj2 (service$or department$ or room$or centre$ or center$or unit$)).ti,ab. 23 (“acute care” or “emergency care”).mp. 24 (emergicenter$or emergicentre$).mp. 25 (((prehospital or pre-hospital) adj2 emergenc$adj2 care$) or (“prehospital care” or “pre-hospital care”)).mp. 26 (emergenc$adj2 (outpatient$ or out-patient$) adj2 unit$).mp. 27 ((ems or ed or er) and emergenc$).mp. 28 (“observation unit$” or “observation area$” or “holding unit$” or “holding area$”).ti,ab. 29 “Canadian Triage and Acuity Scale”.mp. 30 ambulance$.ti,ab. 31 or/18–30 32 17 and 31
Table AIV

HealthSTAR (Health Services Technology, Administration, and Research)—Ovid version

Box AI

### Science citation index expanded

#### String terms

##### Web of Science®

TS=crowd* OR TS=overload* OR TS=emergency department* volume*

OR TS=gridlock OR TS=access block* OR TS=leave without treatment

AND

TS=emergency medical service* OR TS=emergency service* OR TS=trauma center* OR TS=ambulance* OR TS=triage OR TS=prehospital care OR TS=acute care OR TS=emergency care OR TS=hospital emergenc* OR TS=emergency-department* OR TS=public hospital* emergenc*

Box AII

### Dissertation abstracts

#### String terms

##### ProQuest®

(((Overcrowding) OR (crowding) OR (access block) OR (left without being seen) AND (emergency))) AND PDN(>10/1/2004)

##### ABI/INFORM Global ProQuest®

(((Overcrowding) OR (crowding) OR (access block) OR (left without being seen) AND (emergency))) AND PDN(>10/1/2004)

View Abstract

## Footnotes

• Funding This study was funded by a grant from the Canadian Institutes for Health Research (CIHR; 200810KRS). MS is supported by CIHR as an Applied Chair in Health Services and Policy Research (Ottawa, ON). CV-R is supported by CIHR in partnership with the Knowledge translation branch. BHR is supported by the 21st Century Canada Research Chairs program through the government of Canada (Ottawa, ON).

• Competing interests MJB, BRH and BHR are authors of one of the included studies.

• Provenance and peer review Not commissioned; externally peer reviewed.

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