Ambulance deployment without transport: a retrospective difference analysis for the description of emergency interventions without patient transport in Bavaria.

Background: Not all patients who call the ambulance service are subsequently transported to hospital. In 2018, a quarter of deployments of an emergency ambulance in Bavaria were not followed by patient transport. This study describes factors that influence patient transport rates.

Method: This is a retrospective cross-sectional study based on data from all Integrated Dispatch Centres of the Free State of Bavaria in 2018. Included were ambulance deployments without emergency physician involvement, which were subdivided into ambulance deployments without transport and ambulance deployments with transport. The proportion of transported patients were determined for the primary reasons for deployment and for the different community types. On-scene time was compared for calls with and without patient transport. Differences were tested for statistical significance using Chi tests and the odds ratio was calculated to determine differences between groups.

Results: Of 510,145 deployments, 147,621 (28.9%) could be classified as ambulance deployments without transport and 362,524 (71.1%) as ambulance deployments with transport.The lowest proportion of patients transported was found for activations where the fire brigade was involved ("fire alarm system" 0.6%, "fire with emergency medical services" 5.4%) and "personal emergency response system active alarm" (18.6%). The highest transport rates were observed for emergencies involving "childbirth/delivery" (96.9%) and "trauma" (83.2%). A lower proportion of patients is transported in large cities as compared to smaller cities or rural communities; in large cities, the odds ratio for emergencies without transport is 2.02 [95% confidence interval 1.98-2.06] referenced to rural communites. The median on-scene time for emergencies without transport was 20.8 min (n = 141,052) as compared to 16.5 min for emergencies with transport (n = 362,524). The shortest on-scene times for emergencies without transport were identified for activations related to "fire alarm system" (9.0 min) and "personal emergency response system active alarm" (10.6 min).

Conclusion: This study indicates that the proportion of patients transported depends on the reason for deployment and whether the emergency location is urban or rural. Particularly low transport rates are found if an ambulance was dispatched in connection with a fire department operation or a personal emergency medical alert button was activated. The on-scene-time of the rescue vehicle is increased for deployments without transport. The study could not provide a rationale for this and further research is needed. Trial registration This paper is part of the study "Rettungswageneinsatz ohne Transport" ["Ambulance deployment without transport"] (RoT), which was registered in the German Register of Clinical Studies under the number DRKS00017758.