The goal of this clinical trial is to evaluate whether rapid blood tests performed in the ambulance can be implemented in routine prehospital assessment of adults who are initially considered for transport to hospital. Ambulance clinicians frequently assess adults who are transported to hospital but discharged shortly after arrival without requiring advanced diagnostic testing or treatment.

In this study, researchers will examine whether adding rapid point-of-care blood testing (POCT) at the scene supports ambulance clinicians and Emergency Medical Dispatch Centre (EMDC) physicians in making more informed decisions about hospital conveyance. POCT provides rapid measurements of biomarkers including infection markers, electrolytes, kidney function, blood counts, and total carbon dioxide, a proxy measure related to acid-base status.

Ten ambulance clusters will participate in a matched, cluster-randomized design. Half will provide standard care, and half will have access to POCT following consultation with an EMDC physician in patients who would otherwise be considered for hospital transport.

The main question is whether prehospital POCT can be performed, documented, and made available before the final conveyance decision in routine ambulance-based assessment. The study will also examine whether access to POCT is associated with a higher proportion of patients remaining at home rather than being transported to hospital.

Safety outcomes will include hospital admission within 24 hours among non-conveyed patients, short-stay hospitalization, intensive care unit (ICU) admission, and 30-day mortality.

This study will evaluate the implementation of POCT-supported decision-making in prehospital care and explore whether it may increase non-conveyance without compromising patient safety.

Many adults assessed by ambulance services are transported to hospital but discharged shortly after arrival without requiring advanced diagnostic testing or treatment. These potentially avoidable admissions contribute to emergency department crowding and increased healthcare utilization. Improving prehospital decision-making may reduce unnecessary hospital transports while maintaining patient safety. This study evaluates whether rapid point-of-care blood testing performed by ambulance clinicians can be implemented in routine prehospital assessment and support more informed decisions regarding hospital conveyance following an emergency call.

This is a prospective, matched, parallel, cluster-randomized trial conducted within the Prehospital Emergency Medical Services (EMS) of the Central Denmark Region, Denmark. Ten ambulance clusters are included and allocated in a 1:1 ratio to either an intervention strategy integrating point-of-care testing (POCT) into the prehospital assessment or to standard care. Prior to randomization, clusters are matched in pairs based on their historical non-conveyance rate during the preceding six months, overall case volume, and geographic characteristics to ensure balance in baseline practice patterns and workload and to reduce between-cluster heterogeneity. Each matched pair is then randomized to either the intervention or control group.

Participants are adults attended by participating ambulance clusters following an emergency call or GP-commissioned ambulance dispatch through the Emergency Medical Dispatch Centre (EMDC). In the intervention clusters, POCT may be performed in clinically stable patients who would otherwise be considered for hospital conveyance based on the initial on-scene ambulance assessment.

The intervention consists of on-scene biochemical testing using portable POCT devices. The iSTAT Alinity system with CHEM8+ cartridges measures sodium, potassium, chloride, calcium, urea, creatinine, glucose, and total carbon dioxide. QuickRead go is used to measure C-reactive protein and hemoglobin, and HemoCue WBC DIFF is used to measure leukocyte count. Control clusters follow existing assessment procedures without access to POCT. Apart from access to POCT devices and results, all other aspects of clinical management follow standard regional EMS practice.

The primary objective is to evaluate whether prehospital POCT can be implemented in routine ambulance-based assessment. The primary outcome is implementation of prehospital POCT, defined as the proportion of intervention-cluster attended patient encounters within the study population in which POCT was attempted, at least one valid POCT result was obtained and documented, and the result was available before the final conveyance decision.

Non-conveyance is retained as a key secondary clinical outcome and will be compared between randomized intervention and control clusters according to the intention-to-treat principle. Safety and clinical outcomes include hospital admission within 24 hours among non-conveyed patients, short-stay hospitalization, total hospital length of stay, intensive care unit admission, and 30-day mortality.

The trial is not powered to detect definitive differences in non-conveyance or safety outcomes. Instead, it is designed to estimate key implementation parameters, including the proportion of attended patient encounters in which POCT is attempted, the proportion of attempts yielding a valid result, documentation completeness, and availability of POCT results before the final conveyance decision. Clinical outcomes will be interpreted as secondary and exploratory and used to inform the design of a future definitive effectiveness trial.

Ethics and regulatory oversight:

The study has been assessed by the Central Denmark Region Committees on Health Research Ethics (Denmark) and determined not to constitute a health research study under Danish legislation (Consolidation Act on Research Ethics Review of Health Research Projects, Section 2(1)). Therefore, the study does not require approval from a research ethics committee, and formal ethics approval was not obtained.

In accordance with this determination, individual informed consent is not required, as the study is conducted at the cluster level within routine care without alteration of standard treatment pathways beyond the availability of point-of-care testing.

All data are handled in compliance with applicable data protection regulations. The determination is documented in a formal written statement from the Central Denmark Region Committees on Health Research Ethics. This documentation is included as an appendix to the Statistical Analysis Plan. No biological samples are stored for research purposes beyond immediate clinical analysis.

Inclusion Criteria:

• Adults aged ≥18 years
• Emergency call or general practitioner-commissioned ambulance dispatch following telephone triage only, including video streaming triage, resulting in ambulance dispatch
• Initial on-scene assessments performed by the ambulance crew
• Patients initially considered for hospital conveyance based on clinical assessment
• Following telemedical consultation with an Emergency Medical Dispatch Centre (EMDC) physician, deemed eligible for point-of-care blood testing (POCT)
• Hemodynamically and clinically stable according to predefined operational stability criteria (including Glasgow Coma Scale, blood pressure, oxygen saturation, and heart rate), with final eligibility determined by the EMDC physician based on overall clinical assessment and the patient's baseline status

Exclusion Criteria:

• Non-emergency calls (e.g., interfacility transport or scheduled patient transport)
• General practitioner-commissioned ambulance dispatches where the patient has been physically assessed by a general practitioner or another physician before ambulance arrival
• Immediate need for emergency transport to hospital as determined by clinical assessment
• Persistent unstable vital signs outside predefined operational thresholds, except for known chronic baseline deviations (e.g., reduced oxygen saturation in patients with chronic obstructive pulmonary disease or chronic tachyarrhythmia in atrial fibrillation)
• Inability to obtain venous or capillary blood samples
• Prior participation in the study within 30 days (to ensure complete outcome follow-up)

Personnel in the control (non-intervention) clusters are masked to study allocation. They are not informed that their ambulance cluster is serving as part of the control group in the trial.