New Zealand paramedics increasingly discharge patients at scene instead of transporting them to hospital. This change in practice has developed in response to greatly increased low-acuity workload – an increase exceeding population growth. These changes are typical of trends in Emergency Medical System (EMS) workload and practice in high-income countries worldwide. However, the outcomes of patients discharged-at-scene are poorly understood and the safety of this change in EMS practice is unknown. New Zealand paramedics use an electronic non-transport checklist (eNTC) to support discharge-at-scene decisions, but the effectiveness of this checklist in reducing the rate of adverse outcomes from discharge-at-scene is also unknown.

The aim of this thesis is to explore the association between using the eNTC and mortality of patients discharged-at-scene by paramedics in New Zealand by a) establishing the 1-, 3- and 7-day mortality of patients discharged-at-scene by paramedics in New Zealand, b) establishing the frequency of eNTC use, c) identifying any association between eNTC use and 7-day mortality, d) identifying variables associated with 7-day mortality (other than eNTC use) and e) identifying variables associated with eNTC use.

This retrospective cohort study linked data from St John New Zealand EMS electronic patient report forms (ePRFs) and computer aided dispatch (CAD) with mortality data from the New Zealand Ministry of Health. The observational study employed a quantitative approach and reviewed 60,640 cases of patients discharged-at-scene by paramedics from July 2016 to October 2017.

This study found that 59 patients died within one day: a mortality rate of 0.1%, 116 patients died within three days: a mortality rate of 0.2%, and 279 patients died within seven days of being discharged-at-scene: a mortality rate of 0.5%. These mortality rates are equivalent to reported rates of mortality in studies of discharge-at-scene in Australia and the United Kingdom. This study found that the eNTC was used in 36.8% of cases and using the eNTC was associated with reduced 7-day mortality (UOR 0.58; 95% CI, 0.45, 0.77; p < 0.001).

After controlling for confounding, three factors remained associated with reduced 7-day mortality after discharge-at-scene. These factors were: single-crew compared to non-single-crew (AOR 0.46; 95% CI, 0.30, 0.72; p = 0.001), eNTC use compared to non-use (AOR 0.60; 95% CI, 0.45, 0.81; p = 0.001), and summer season compared to winter (AOR 0.60; 95% CI, 0.38, 0.91; p = 0.026).

Conversely, four variables remained associated with increased mortality. These were: older age ≥ 65 years compared to younger age (AOR 6.10; 95% CI, 4.27, 8.71; p < 0.001), more severe clinical status compared to less severe clinical status (AOR 3.50; 95% CI, 2.65, 4.61; p < 0.001), longer time on scene compared to shorter time on scene (AOR 2.08; 95% CI, 1.52, 2.85; p < 0.001) and male patient sex compared to female patient sex (AOR 1.57; 95% CI, 1.21, 2.04; p = 0.001). Patient ethnicity was determined not to have an association with mortality.

This research gives an understanding of the outcomes for patients discharged-at-scene by paramedics and can be used as a benchmark to enable improvements in clinical practice. To the best of our knowledge, this study is the first to explore the use of a checklist to improve outcomes of patients discharged-at-scene. An association between paramedic use of a checklist and improved patient safety is established. Low voluntary compliance with checklist use was observed: this supports making its use compulsory.