Objective When planning and dimensioning an emergency medical system, knowledge of the population serviced is vital. The amount of literature concerning the prehospital population is sparse. In order to add to the current body of literature regarding prehospital treatment, thus aiding future public health planning, we describe the workload of a prehospital anaesthesiologist-manned mobile emergency care unit (MECU) and the total population it services in terms of factors associated with mortality.

Participants The study is a register-based study investigating all missions carried out by a MECU operating in a mixed urban/rural area in Denmark from 1 May 2006 to 31 December 2014. Information on missions was extracted from the local MECU registry and linked at the individual level to the Danish population-based databases, the National Patient Registry and the Civil Registration System.

Primary and secondary outcome measures Primary outcome measures were number of missions and number of patient contacts. Secondary patient variables were mortality and association between mortality and age, sex, comorbidity, prior admission to hospital and response time.

Results The MECU completed 41 513 missions (mean 13.1 missions/day) having 32 873 patient contacts, corresponding to 19.2 missions and 15.2 patient encounters per 1000 patient years. Patient variables: the median age was 57 years (range 0–108 years), 42.8% (42.3% to 43.4%) were women. For patients admitted to hospital alive, 30-day mortality was 5.7% (5.4% to 6.0%); 90-day mortality was 8.1% (7.8% to 8.5%) while 2-year mortality was 16.4% (16.0% to 16.8%). Increasing age, male sex, comorbidity and prior admission to hospital but not response time were associated with mortality.

Conclusions Mortality following an incident requiring the assistance of a MECU was high in the first 2 years following the incident. MECU response time assessed as a continuous parameter was not associated with patient outcome.