Intended for healthcare professionals


Trends in demand for emergency ambulance services in Wiltshire over nine years: observational study

BMJ 2002; 324 doi: (Published 16 March 2002) Cite this as: BMJ 2002;324:646
  1. Hannah Wrigley, research assistanta,
  2. Steve George, reader in public health (pluto{at},
  3. Helen Smith, reader in primary care medicineb,
  4. Helen Snooks, senior lecturer in health and social care researchd,
  5. Alan Glasper, professor of nursing studiesc,
  6. Eileen Thomas, executive director of nursinge
  1. a Health Care Research Unit, Community Clinical Sciences Division, School of Medicine, University of Southampton, Southampton SO16 6YD
  2. b Academic Department of Primary Medical Care, Community Clinical Sciences Division, School of Medicine, University of Southampton
  3. c School of Nursing, University of Southampton
  4. d University of Wales, Swansea, Wales SA2 8PP
  5. e Portsmouth Health Care NHS Trust, Portsmouth PO3 6DP
  1. Correspondence to: S George
  • Accepted 20 September 2001

Demand for emergency medical services in the United Kingdom is rising.1 Research into the type of patients transported by emergency ambulances and the severity of their illness has tended to focus on identifying people who use the service inappropriately rather than factors influencing demand, and our understanding of the increase in demand is poor. 2 3

In Wiltshire, a largely rural county in the south west of England, the number of emergency transports of patients increased from 11 268 in 1988 to 16 814 in 1996, a crude increase of 49%.4 This increase is often attributed to general practitioners redirecting patients with urgent problems to the ambulance service, particularly out of surgery hours. Over the same period, however, urgent transports booked by general practitioners rather than in response to a 999 call rose from 9982 to 13 951 (40%). We examined the reasons for this rise.

Use of ambulance services in Wiltshire. Values are numbers (percentages) unless otherwise specified

View this table:

Methods and results

We conducted a retrospective analysis of emergency ambulance despatches using a random sample of records held by Wiltshire Ambulance Service NHS Trust. From each year in nine years' records (1988-96) we sampled 14 days, stratified by season, providing a dataset of 126 days of calls. Data were drawn from AS1 forms (completed by call takers) and from patient report forms (completed by paramedics). We used the system of call classification used by the trust to categorise data on the nature of incidents for analysis. We used indirect age standardisation based on the year with the most complete age data (1994) to account for demographic changes over the nine years (see methodological supplement on We calculated significance of trends with EpiInfo 6.03, using χ2 for trend.

Our sample contained details of 6100 calls relating to 5821 incidents. For 1225 (21%) of these, patient report forms rather than AS1 forms had been filled in. The table shows the numbers of vehicles despatched, incidents, and patients transported in each year.

A 72% increase in incidents attended over nine years reduced to 53% after standardisation for age. The proportion of incidents in response to a call from a general practitioner, or incidents where one was present, remained fairly constant over the study period, whereas the proportion of calls made by patients and relatives rose from 11.8% to 20.1% (see tables A and B on Calls from other emergency services peaked in 1990. The category showing an increase out of line with that seen overall was “sudden illness at home.” In this category, incidents described in general terms such as “collapse” fell from 35% to 20%, whereas those attributed more specifically to cardiac problems rose from 22% to 31% and those attributed to respiratory problems from 12% to 21% (see table C on


Demand for emergency ambulances has risen, and there is evidence that people are using more specific terminology to describe emergency incidents. We found no evidence of a transfer of general practitioners' workload to the emergency ambulance service. The fall in mortality across all age groups in Western society leads us to conclude that the demand threshold is falling.5

Callers' perceptions of urgency are known to be unreliable, and a wider range of responses from service providers may be the most appropriate way to manage rising demand.3 The integration of the gateway to primary care out of hours with NHS Direct might provide one way of accomplishing this. Research identifying influences on callers' perceptions of urgency is necessary if we are to improve our understanding of the demand for emergency care and our ability to plan for the future.


We thank members of Wiltshire Ambulance Services Trust who provided data, tea, and moral support during long days of searching for records. We also thank the NHS Executive South and West Research and Development Directorate for funding this study. The opinions expressed, however, are those of the authors alone.

Contributors: SG, H Smith, AG, and ET obtained funding for this study. HW collected and categorised data. HW and SG undertook the analysis with advice from all authors. Specialist advice on ambulance services was provided by H Snooks. All authors participated in the interpretation of findings, writing up and editing of the paper. SG is the guarantor.


  • Competing interests None declared.

  • Embedded ImageExtra tables and a methodological supplement appear on


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