Avoidable adverse events (including redirection of care to another urgent care provider), quality of life, patient and/or carer satisfaction, waiting time in ED, including A&E 4 hour waiting time target, and mortality were considered by the guideline committee to be critical outcomes.

ED avoidance was considered to be an important outcome.

There was evidence from 5 observational studies; 3 studies compared standalone walk-in centres with no stand-alone walk-in centres, 1 study compared EDs with co-located walk-in centres with EDs without co-located walk-in centres and 1 study compared co-located minor injury units with absence of co-located minor injury units.

Stand-alone units

Minor injury units

No evidence was found specifically for stand-alone minor injury units, although the nomenclature and the definitions appear very interchangeable.

Urgent care centres

No evidence was found specifically for stand-alone urgent care centres, although the nomenclature and the definitions appear very interchangeable.

Walk-in centres

There was evidence from 3 studies comparing stand-alone walk-in centres with absence of stand-alone walk-in centres. The evidence suggested that stand-alone walk-in centres may provide a benefit in terms of ED avoidance (mean monthly attendance rates). However, there was no effect on ED avoidance expressed as annual non-ambulance attendance rates per 1000 population. The evidence for ED avoidance was inconsistent due to different reported methodologies (mean and rate ratio were reported separately). There was no evidence for avoidable adverse events, re-consultation, quality of life, patient and/or carer satisfaction, waiting time in ED and mortality.

The committee highlighted the importance of how the units or centres were defined by the studies in their consideration of the evidence. With regard to studies comparing stand-alone walk-in centres with absence of a walk-in centre, 1 study was based on a GP-led walk-in centre, open from 8am to 9pm, 7 days a week; 1 study assessed the impact of 10 different walk-in centres, which varied in terms of setting, available services and staffing; the other study did not specify details about staffing or set-up, other than that it shared the same premises, entrance and triage process as a minor injuries unit.

Co-located units:

Urgent care centres

No evidence was found for co-located urgent care centres.

Walk-in centres

One study (number of participants not reported) suggested that co-located walk-in centres provided benefits in terms of ED avoidance mean monthly attendance rates. The evidence suggested there was an increase in ED avoidance patient throughput (mean monthly attendances). There was no effect on avoidable adverse events.

There was no evidence available for re-consultation, quality of life, patient and/or carer satisfaction and mortality.

Minor-injury units

One study comprising 584,321 participants evaluated co-located minor injury units for improving outcomes in secondary care. The organisation of the minor injury unit was not defined, other than stating that there were no major changes in staffing levels before and after its introduction. The evidence suggested there was no effect on waiting time in ED and mortality. There was no evidence available for ED avoidance, avoidable adverse events, re-consultation, quality of life and patient and/or carer satisfaction.

Given the lack of evidence for avoidable adverse events, quality of life, patient and/or carer satisfaction and mortality and the heterogeneous evidence for ED avoidance, the committee did not consider increased compliance with the A&E 4 hour waiting time target alone to be sufficient to justify a recommendation.

The committee therefore decided not to make a recommendation for minor injury units, urgent care centres or walk-in centres. However, there was no evidence to suggest that these units are harmful. Based on the heterogeneity of the models used in the studies and the lack of consistent evidence, the committee agreed that more evidence is required to inform a recommendation. It was therefore decided to recommend that further research should be carried out.

One comparative cost analysis was included which compared emergency departments before and after the introduction of co-located walk-in centres with matched control emergency departments. The study showed a modest cost saving in the mean cost per patient in the base-case analysis (£3), and therefore it might be cost-effective if outcomes are at least similar. However, the study did not give a clear description of the staffing models used in these walk-in centres. The follow-up in the study was short, with the cost analysis conducted for a period of 3 months; hence it may not have captured differences in down-stream costs. Together with the lack of a clear benefit for walk-in centres from the clinical evidence review, the committee considered the evidence to support recommending wider implementation of co-located walk-in-centres to be weak.

There was no economic evidence for either MIUs or UCCs, so the unit costs of visits to these centres from the NHS reference costs were also presented to the committee.

It was noted that in the NHS reference costs, the weighted average unit cost of a MIU/UCC visit or walk-in-centre visit (£67 or £46) is less costly than an ED visit (£114). The committee also discussed the current practice in the NHS and reflected that there is variation in how MIUs, UCCs and WiCs are run across the country, which makes it difficult to recommend a specific service configuration and staffing model.

The committee noted that co-location of these units within an ED should allow for economies of scale in terms of sharing resources with the ED (that is, flexing of staff to demand); however, co-location may not always be practical especially in rural areas. Additionally, a concern was expressed that the presence of these units might result in a supplier-induced demand that is, more presentations by people who could have managed without professional intervention, or who could have attended their GP.

Overall, the committee felt that the evidence available was insufficient to support a recommendation for wider implementation within the NHS, preferring instead to make a research recommendation to assess the clinical and cost-effectiveness of these models of care.

All included studies were observational study designs. For the comparison between stand-alone units versus absence and co-located units versus absence, the evidence was considered to be of low to very low quality due to the high risk of bias and imprecision.

The economic evidence was rated as partially applicable with potentially serious limitations. The included study is a comparative cost analysis; hence, QALYs were not used as an outcome measure. There was also uncertainty regarding the applicability of resource use and costs from 2004-2005 to current NHS context. The study had a short follow-up period (cost data analysed for 3 months before and 3 months after the introduction co-located walk-in-centre), so follow-up may not have been long enough to capture all relevant differences in costs and outcomes. Sources of unit costs are not reported and may not be reflective of national unit costs.

Over the last 30 years the NHS has have opened ‘walk-in centres’, ‘minor injury units’, ‘urgent care centres’ and a substantial range of similarly-named facilities that all offer slightly different services, at slightly different times, in different places. This has resulted in a very confusing system for patients. There appears to be no specific definition for any of these units or centres. An NHS “walk-in centre” is defined by Monitor as a site that provides routine and urgent primary care for minor ailments and injuries with no requirement for patients to pre-book an appointment or to be registered at the centre or with any GP practice. The Dudley Group NHS Foundation Trust defines an “urgent care centre” as a unit that offers non-emergency care for walk-in patients who have minor illnesses and injuries that need urgent attention. North Devon Healthcare Trust defines a “minor injuries unit” as a department largely staffed by emergency nurse practitioners (ENPs) working autonomously who look after minor injuries such as lacerations and fractures, and have access to X-ray facilities. NHS choices does not appear to differentiate between the 3 types of units or centres. Walk-in centres (WICs), were established in England in 2009 to improve access to GPs as well as to prevent unnecessary attendances at ED by having extended opening hours and being placed in a convenient location. There are many units located in the major cities particularly in London.

There is no clear definition of what staffing arrangement comprises a walk-in centre, a minor injuries unit or an urgent care centre. There is variability across different units and areas in terms of opening hours, staffing, resources and location (either co-located or stand-alone). All of these factors have a significant impact on case mix.

The committee noted the following definitions applicable to different types of A&E departments²⁷:

• Type 1 A&E department: A consultant led 24 hour service with full resuscitation facilities and designated accommodation for the reception of accident and emergency patients.
• Type 2 A&E departments: A consultant led single specialty accident and emergency service (for example, ophthalmology or dental) with designated accommodation for the reception of patients.
• Type 3 A&E department/Type 4 A&E department/Urgent Care Centre: Other type of A&E/minor injury units (MIUs)/Walk-in Centres (WiCs)/Urgent Care Centre primarily designed for the receiving of accident and emergency patients.

It was agreed that the absence of a consistent terminology for structures and processes and also the level and type of staffing relating to MIUs, UCCs and WiCs makes their evaluation challenging. Future studies should take into account several contextual factors including location (inner-city, urban and rural), opening times (24 hour versus restricted times) staffing composition and expertise, available resources, processes and overall service configuration in their analyses. Proximity to these units could be used as an instrumental variable to evaluate outcomes given the impossibility of randomising populations.

The majority of the evidence came from studies with relatively short follow up periods, which the committee considered to be a significant limitation as it may not reflect long term effects. Future studies evaluating effects over longer time frames would offer the opportunity to account for secular trends and detect population effects.

As well as ED demand, other outcomes should be patient-focussed and rooted in health economics evaluation. The potential impact on other services such as the ambulance service (particularly within rural areas) should be evaluated. Staff exposure to specific health problems within the ED may be reduced as a result of streaming particular groups of patients to specialist centres. Therefore, it would also be useful to assess the impact on staff training and potential staff de-skilling. In summary, the current level of evidence is insufficient to permit a recommendation on the internal or external configuration of such units. Opportunities should be taken to evaluate MIUs, UCCs and WICs using existing services or if local health economies choose to implement such services.