Oscar H. M. Lundberg, Oscar Lapidus, Denise Bäckström
BACKGROUND: Minimising time from injury to hospital admission is considered a key factor in trauma. Trauma care is often centralised to hospitals, which, because of their urban location, make treatment more accessible to patients in densely populated areas. If prehospital time increases with declining population density, an effect on mortality could hence be present. The primary aim of this study was to describe prehospital time intervals across population density groups. A secondary objective was to compare the 30-day mortality rates in these population groups. METHODS: This retrospective cohort study was based on the Swedish Trauma registry (SweTrau) between 2018 and 2019. Based on their home municipality, patients were divided into groups of high, medium or low population density. The time interval distributions were described and compared. Secondary outcomes were reported. A multivariate mortality analysis included time intervals, demographics, injury severity score, physiological parameters and other covariables such as care provided by a prehospital physician. RESULTS: A total of 14,538 patients were included. The distribution across high, medium and low population concentrations was 34%, 47% and 19%, respectively. The response and transport times were significantly longer in the low population group compared with patients from groups high and medium, with a median difference of 4 and 11-15 min, respectively (p < 0.001). The median on-scene time of 20 min was shortest in the medium group with a one minute difference to both other groups (p < 0.001). The crude mortality of 5% in the low density group was significantly lower than in the other two (both 6%) (p = 0.005). However, after adjustment no association between mortality and prolonged prehospital time intervals was seen. The involvement of a prehospital physician in the care was associated with lower mortality (OR 0.60, 95% CI 0.39-0.91; p = 0.02). CONCLUSIONS: Although prehospital time intervals increased with remoteness, these differences were not associated with increased mortality. Further, residing in either high, medium or low density population areas was not consistently associated with mortality.