Data

We used a dataset extracted from the “Connected Health Cities: Data linkage of urgent care data” study (known as the “CUREd research database”) [14]. The CUREd database has approval from a National Health Service (NHS) Research and Ethics Committee, overseen by the NHS Health Research Authority’s Research Ethics Service (18/YH/0234), and from the NHS Health Research Authority (HRA), directly (18/CAG/0126, previously 17/CAG/0024), to receive health and social care data without patient consent for patients of emergency and urgent care services in Yorkshire and Humber.

The CUREd dataset includes routinely collected healthcare data for all NHS 111 calls in the Yorkshire & Humber region of the UK from the beginning of April 2013 to the end of March 2017. It also includes data concerning ED attendances and all emergency hospital admissions from 13 NHS Acute Trusts across Yorkshire & Humber. The data used in the study comprised de-identified data extracted from routinely collected information on every NHS 111 call made in the region between the specified dates. Additionally, it included any attendance at a type 1 ED (a consultant-led 24 hour service with full resuscitation facilities and designated accommodation for the reception of ED patients) linked to the corresponding patient within 48 hours of the NHS 111 call, and any subsequent hospital admission made up to one night after an ED attendance, indicated by an admitted patient care (APC) record for that patient. Multiple NHS 111 calls from a single patient are included, however, for the present analysis only the final call within 48 hours before an ED attendance was linked to that attendance, to avoid multiple representations of attendances. The data included only those patients aged 16 or over at the time of the NHS 111 call.

Data linkage

ED attendances and hospital admissions were traced following an NHS 111 call by the linkage of the routine datasets listed above. The aim was to identify all records amongst the datasets that correspond to the same individual. This was achieved using the following method:

1. Assign each distinct (valid NHS Number, valid date of birth [DOB]) pair a new CUREd ID.
2. Attempt to link records with a valid NHS Numbers but no valid DOB to a CUREd ID based on approximate birth year (calculated from activity date and age at activity).
3. Attempt to link remaining records to an assigned CUREd ID by Provider code, Provider Patient ID and DOB matches (provided this only matches one CUREd ID).
4. Attempt to link remaining records to an assigned CUREd ID by First name, Last name, Sex, DOB and postcode matches (provided this only matches one CUREd ID).
5. Attempt to link remaining records to an assigned CUREd ID by Sex, DOB and postcode matches (provided this only matches one CUREd ID).
6. Cluster records by agreement on any of the following patterns:
   1. Provider code, Provider Patient ID and DOB matches
   2. First name, Last name, Sex, DOB and postcode
   3. Sex, DOB and postcode matches and assign each distinct cluster to a new CUREd ID.
7. Assign each remaining record to its own CUREd ID.

Analysis

For this exploratory investigation, all analyses were descriptive in nature. For each NHS 111 call record in the dataset pertaining to an adult patient (age 16+), we determined whether an ED attendance was made by that patient within 48 hours of the call, and if so, whether this was followed by an emergency hospital admission. This examination was broken down by the category of advice given to each caller. These categories are known as ‘dispositions’ and include:

1. Ambulance dispatch. The NHS 111 call handler transfers the call to 999 for an ambulance response. Note that not all ambulance dispatches will result in further transportation to ED, with this being deemed unnecessary by paramedics, or patients being conveyed directly to ward bypassing ED.
2. Attend ED. The caller is advised to attend ED within a given time frame by their own means.
3. Primary or community care. The caller is advised to seek primary or community care, for example a GP, dental practitioner or community pharmacy, within a given time frame.
4. Self care. The caller is not advised to seek additional care services. This also includes incidences where the caller abandoned the call without receiving a recommendation.
5. Other service. The caller is advised to seek care from a service not covered by the above categories. Services included will depend on their local service configurations but may include, for example, mental health services, a district nurse, or midwife.

We examined the proportion of callers in each disposition, the proportion of callers attending ED within 48 hours of the NHS 111 call, and the proportion of ED attendees either classed as non-urgent or experiencing a subsequent hospital admission. Non-urgent cases were defined as attendances at a type 1 ED, as a first attendance, but who were subsequently identified as not receiving investigations, treatments or referral that required the facilities of a type 1 ED [15]. Calls were split by various categories and combinations thereof to explore possible differences in patient flow. These categories included:

• Disposition
  1. ○. Ambulance dispatch, ED, Primary or community care, Self-care, Other service
  2. ○. Detailed disposition code including recommended time to access care
• Age category
  1. ○. 16–44, 45–74, 75+
• Clinical adviser handled call
  1. ○. Yes, no
• Year of call
  1. ○. 2013–2017

Outcomes considered for each category included:

• Percentage of callers attending ED within 4, 24, or 48 hours of the NHS 111 call;
• Time taken to attend ED;
• Percentage of ED attendances classed as non-urgent;
• Percentage of ED attendances admitted.

Call outcomes by NHS 111 disposition category

In this section we further examine trends for those patients given a disposal code for self or primary care, ambulance dispatch and recommendation to attend ED. We do not explore those provided an ‘Other service’ disposal code, since this represents a heterogeneous group for whom generalisations are unlikely to be informative.

Low acuity dispositions: Self-care & primary care.

Using our linked dataset we identified that of those advised to self-care or contact primary / community care, 10.5% (n = 289,748) attended the Emergency Department (ED) within 48 hours of the NHS 111 call. A greater percentage of those patients advised to self-care than to access primary care decided to attend the ED (18.2% vs 8.5%). When we analysed the time of attendance at ED, we found that the majority of patients attending ED do so within 4h of their NHS 111 call. This is especially the case for those adults advised to self-care, compared to those advised to access primary care (87.4% vs 62.1% of callers). For adults advised to seek primary care, Fig 2 shows a longer and heavier tail to the distribution of attendance time.

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Fig 2. Distribution of hours taken to attend ED for those advised to different dispositions.

Solid vertical lines denote 24 hours from the call; dashed lines denote 4 hours.

https://doi.org/10.1371/journal.pone.0251362.g002

Of those callers initially advised to seek primary or community care, or to self-care, but who subsequently attended ED, 36.7% (n = 106,207) were then admitted to hospital (equating to 3.8% of all callers in this disposition). We found within this disposition group that 11.7% of attendances at the ED were non-urgent (n = 33,817).

We further examined final disposition codes provided by NHS 111 for each call. We found that those given a primary care disposition (either as face to face, or telephone contact) recommended within 1–2 hours had a higher likelihood of resorting to an ED attendance than those requiring primary care over a longer time period (Table 2). They also attended faster: the average time of attendance at ED for shorter-timescale patients was around 2.5–3 hours following the NHS 111 call, whereas those receiving a longer-timescale disposition (12 hours or more) was around 3.5–6 hours.

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Table 2. Time to attend ED for those advised to contact primary care within different time intervals.

https://doi.org/10.1371/journal.pone.0251362.t002

Examination of subgroups

Age group.

We examined details for patients of different ages to identify any systematic differences in these groups. There was little apparent difference in the average time to attend, and the percentage of callers attending ED from different age groups when ignoring disposition (S2 Fig, Table 1). In all age brackets, the majority of those attending ED did so within 4 hours, and almost all within 24 hours.

When age groups are further broken down by disposition, some patterns of interest are revealed (Fig 3). There were fewer primary care and self-care disposals among older patients. In contrast, more patients in the oldest group were sent an ambulance or directed to other healthcare services. Few older patients were advised to attend ED–likely due to increased barriers to transport or greater concern regarding older patient welfare. While there were differences in the profile of dispositions, similar percentages of patients attend ED from each disposition, regardless of their age bracket. In total, around 21% of patients in the youngest age bracket attend ED, compared to around 28% of patients in the oldest age bracket.

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Fig 3. Proportion of NHS 111 callers given each disposition and attending ED, split by age.

Top: percent of NHS 111 callers in each age group receiving each disposition; e.g., 66.2% of 16–44 year-olds were advised to contact primary care. Bottom: percent of NHS 111 callers in each age-disposition group who attended ED; e.g. 7.7% of 16–44 year-olds who were advised to contact primary care attended ED.

https://doi.org/10.1371/journal.pone.0251362.g003

We found a notable difference in the relative percentages of ED attendees that were subsequently admitted to hospital in the difference age groups (Fig 4). Far higher proportions of older patients were admitted following an ED attendance than younger patients. This held even for low acuity dispositions; for example, nearly 60% of older patients who attended ED, who were originally advised to self-care, were admitted to hospital. This is in contrast to the same group in the youngest age bracket, of whom just over 20% were admitted. In all age groups, and across all dispositions, there were relatively few ED attendees who were classed as non-urgent. Indeed, in all but one subgroup (16–44, advised to attend ED), larger numbers of patients were subsequently admitted than were classed as non-urgent.

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Fig 4. Proportion of ED attendees from each disposition considered non-urgent, and those admitted, by age.

Top: percent of NHS 111 callers in each age-disposition group who attended ED, who were classed as non-urgent; e.g., 14.1% of callers aged 16–44, who received a primary care disposition but attended ED, were classed as non-urgent. Bottom: percent of NHS 111 callers in each age-disposition group who attended ED, who were subsequently admitted; e.g., 25.5% of callers aged 16–44, who received a primary care disposition but attended ED, were admitted. Note that relative numbers of patients in these disposition groups are markedly different (see Fig 3).

https://doi.org/10.1371/journal.pone.0251362.g004

Clinical advisers.

Finally, we explored the data for any differences in attendance behaviour depending on whether a clinical adviser handled the NHS 111 call or not. As with age groups, we found little difference overall on the average time to attend, or percentage of callers attending ED, based on the recommendation of a clinical adviser (S3 Fig, Table 1). Again, however, once broken down by disposition, some differences were revealed between calls taken by clinical advisers and non-clinical call handlers (Fig 5; although it is important to note that clinical advisers may be more likely to deal with borderline or complex cases–see discussion). Clinical advisers tended to direct fewer patients to primary/community care or other care services, and more to care for themselves. This may reflect a greater confidence in determining minor health issues among this group.

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Fig 5. Proportion of callers given each disposition and attending ED, split by call handler.

Top: percent of NHS 111 callers advised by each adviser type receiving each disposition; e.g., 50.1% of those advised by a clinical adviser received a primary care disposition. Bottom: percent of NHS 111 callers in each adviser-disposition group who attended ED; e.g. 9.6% of those advised by a clinical adviser who received a primary care disposition attended ED.

https://doi.org/10.1371/journal.pone.0251362.g005

Generally there were few differences in the proportions of patients attending ED, or classed as non-urgent, from each disposition regardless of the type of adviser. However, callers seem slightly more likely to follow advice to self-care given by a clinical adviser, which may reflect more faith in the adviser’s decision (Fig 5). In all but one group, more patients were admitted to hospital than were classed as non-urgent, and this difference was often marked. The one exception to this is, as before, were patients who were originally advised to attend ED; specifically those who were advised by a non-clinical call handler. The main difference between clinical advisers and non-clinical call handlers is the proportion of patients originally directed to other services. In this group, far more ED attendees who were advised by a non-clinical call handler were subsequently admitted to hospital (Fig 6). This may reflect a better understanding held by clinical advisers of other services available and the appropriate circumstances under which to direct patients to those services. Note, however, there are relatively few absolute numbers of patients in this category.

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Fig 6. Proportion of ED attendees from each disposition considered non-urgent, and those admitted, by call handler.

Top: percent of NHS 111 callers in each adviser-disposition group who attended ED, who were classed as non-urgent; e.g., 10.5% of callers who were advised by a clinical adviser and received a primary care disposition but attended ED, were classed as non-urgent. Bottom: percent of NHS 111 callers in each adviser-disposition group who attended ED, who were subsequently admitted; e.g., 38.8% of callers who were advised by a clinical adviser and received a primary care disposition but attended ED, were admitted. Note that absolute numbers of patients in these disposition groups are markedly different (see Fig 5).

https://doi.org/10.1371/journal.pone.0251362.g006

Clinical implications

Following the recent pandemic, a ‘call-first’ model has been proposed by organisations such as the UK Royal College of Emergency Medicine [22], and currently being piloted in several regions across England [12, 23, 24]. This aims for NHS 111 to act as a non-compulsory ‘gatekeeper’ to emergency health services, and will encourage the public to call NHS 111 before attending other services, a model already practiced in some Scandinavian countries including Denmark [25]. The aim is for appropriate triaging of calls to manage suspected COVID-19 disease, but also to manage demand on systems more widely. Understanding the pathways of patients following calls to telephone helplines to ensure triaging is appropriate and effective is vital if future strategies include adopting the call-first model to manage demand and also risk in future pandemics. More broadly, understanding these pathways identifies areas in which the reasons for non-compliance and their interplay with the nature of NHS 111 advice must be further examined; this is crucial for future policy aimed at reducing non-urgent attendances and improving compliance.

During the COVID-19 crisis we have also seen primary care and hospital outpatients swiftly move from a face-to-face based service to telephone based in many instances, for patients both with and without suspected COVID-19 [26]. However there is a lack of evidence regarding safety, efficacy and impact of this approach. Understanding the role of NHS 111 within these new approaches is especially important for emergency care where access by the most marginalised in society will be vital–such as the elderly, those with chronic ill health and mental health problems.

Further research

These findings raise additional questions for future investigation. It is particularly important to understand discrepancies in ED attendances and admissions: both why such a large proportion of patients given a low-acuity disposition are admitted to hospital when they do attend ED, and why relatively few patients directed to ED are subsequently admitted to hospital whereas a large proportion of these attendances are considered avoidable. In future work we will explore differences between those who are and are not subsequently admitted, and those who are classed as non-urgent to reveal insights about trends in these dispositions, at the level of detailed disposition codes with recommended time to access care where applicable. This will help to reveal insights regarding more detailed circumstances under which NHS 111 advice is ultimately not followed.

It is also of interest to explore the differences we found between age groups; specifically whether older patients are less likely to seek telephone help for less urgent healthcare issues, or whether call handlers and emergency care doctors are more cautious in their referrals and admissions of older patients, or that older patients’ lack of access to or provision of care at home leads to less urgent cases resulting in admission. The lack of differences between clinical and non-clinical advisers will also be investigated further in future work which will aim to understand differences in patient case-mix, treatment and diagnosis between those handled by clinical and non-clinical advisors.

Strengths and limitations

This study represents an analysis of a large dataset covering 4 full years’ data, and thus provides a particularly comprehensive overview of patient pathways following a call to NHS 111. This is also the first study examining linked data to look at the post-call pathway in detail, including distributions of times to attend and details of the relative urgency of those who were and were not advised to attend ED. Our present data is also able to yield more detail regarding case-mix, symptoms and diagnoses, and multiple calls, which will be used to address further questions in future research.

However, unfortunately we currently do not have details regarding other services patients may access following a call, including GP services, so we are unable to draw conclusions about the possible role of onward referrals to ED at intervening points in the pathway; it is likely that in some cases, those advised to seek primary care were then further instructed by a GP to attend ED. In some cases patients may alternatively have been advised to either seek primary care or to self-care, but to attend ED if their condition worsened; unfortunately the data do not capture this level of detail at present. Similarly, we do not have patient level information regarding choices made, restricting the conclusions we are able to draw regarding the reasons for following or not following advice given by NHS 111 advisers.