Ambulance deployment without transport - A retrospective difference analysis for the description of emergency interventions without patient transport in Bavaria

Abstract Background: Not all patients who call the ambulance service are subsequently transported to hospital. 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 (RoT) and ambulance deployments with transport (TP). Patient transport quota (PTQ) 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 (α = 0.05) using Chi2 tests and the odds ratio (OR) was calculated to determine differences between groups. Results: Of 510,145 deployments, 147,621 (28.9%) could be classified as ambulance deployments without transport (RoT) and 362,524 (71.1%) as ambulance deployments with transport (TP). The lowest PTQ was found for reasons with fire brigade involvement ("fire alarm system" 0.6%, "fire with EMS" 5.4%) and "personal emergency response system active alarm" (18.6%). The highest PTQs were for "childbirth/delivery" (96.9% PTQ) and "trauma" (83.2% PTQ). A lower PTQ is observed in large cities than in smaller cities or rural communities; in the community type Large City, the odds ratio for RoT is 2.02 [95% confidence interval 1.98–2.06] referenced to Rural Community. The median on-scene time for RoT was 20.8 minutes (n = 141,052) and for TP was 16.5 minutes (n = 362,524). The shortest on-scene times for RoT were identified for the reasons "fire alarm system" (9.0 minutes) and "personal emergency response system active alarm" (10.6 minutes). Conclusion: This study shows that the transport quota depends on the reason for deployment and the type of municipality. Particularly low PTQs are found in fire brigade and personal emergency response system operations. The engagement times of the rescue vehicle are increased for RoT deployments. 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.