Factors associated with the occurrence of prehospital medical interventions provided by physicians among non-trauma patients: a single-centre retrospective observational study in Japan

Objectives Physician-staffed prehospital units are widely used in many countries. The criteria for predicting fatal injury are well recognised for trauma victims, but there are no criteria for predicting critical condition for non-trauma patients. This study aimed to identify the factors associated with non-trauma cases receiving prehospital interventions by physicians. Design Retrospective observational study. Setting Physician-staffed prehospital unit (car) at a single-base hospital in a suburban city in Japan. Participants Participants were 1058 non-trauma patients who received prehospital medical examinations from April 2014 to December 2017. Outcome measures The outcome was the occurrence of physician-only interventions (POIs) exceeding paramedics' competencies. Univariate analysis and multiple logistic regression analysis were performed. Patient's age and gender, presumed disease category, type of location of the emergency, time of alarm, activation time, activator's occupation, time to arrival, transportation time and the destination facility were included as covariates. Results POIs were provided to 380 (36%) patients. Patient's age, presumed disease category, type of location of the emergency, activator's occupation, time to arrival, transportation time and the destination facility were identified as potential independent factors. Multiple logistic regression analysis found that patient's age, presumed disease category, type of location of the emergency, transportation time and destination facility were the significant independent factors. Transportation times of more than 15min (adjusted ORs (AORs)=4.17, 95% CI 2.59 to 6.72, p<0.01) or 10 to 14min (AOR=3.66, 95%CI 2.32 to 5.79, p<0.01) and patient age of 40-59 years (AOR=3.16, 95%CI 1.66 to 6.01, p<0.01) were the strongest independent factors. Conclusions This study identified the factors associated with non-trauma cases receiving prehospital POIs. Patient's age, presumed disease category, type of location of the emergency and transportation time are independent factors associated with requiring POIs.