Design and setting
Between January and April 2021, an observational study was conducted at the Tehran EMS center and a university-affiliated urban ED in Tehran, Iran. The ED has an average annual census of 60,000 patients. Our ED does not usually receive children (age under 16) because in Iran; the designated children's hospitals are responsible for evaluating the children. Also, our hospital is a level-1 trauma center, and traumatic cases are more frequent in our ED. Among EMS stations in Tehran, four EMS stations that were linked to our ED were selected.
All emergency patients who were transferred to the ED were assessed and followed to find out their 30-day outcome. Sampling was performed during the weekdays from 9 am to 6 pm. Four research nurses were recruited to collect the data and follow up with the patients. They recorded the patients' demographic data (age, gender, traumatic or non-traumatic cause of the event), ESI level, and NEWS. An emergency medicine physician trained research nurses how to gather and record data in a checklist prepared by researchers. The local ethics committee approved the conduct of the study. All data was recorded anonymously and with respect to patients' privacy. Also, informed consent was obtained from the patients, relatives, or legal guardians upon the ED admission for follow up evaluations.
All adult patients (age ≥ 16 years) brought to the ED by EMS providers were included. We excluded the patients who left the ED against medical advice, transferred to other medical centers, had missing triage data or lost follow-up, and were confirmed dead at the scene or upon ED arrival.
Since utilizing NEWS2 requires knowledge regarding the blood gases, which is beyond the scope of our paramedics, we opted to evaluate the NEWS in our prehospital patients .
EMS providers calculated the Patients' NEWS based on their initial observations in the field. They used a downloadable NEWS app installed on their smartphones to calculate the NEWS (https://play.google.com/store/apps/details?id=com.gumptionmultimedia.newsscore). Since this app was not linked to any database, they recorded patients' NEWS in a checklist prepared by the researchers and handed the checklist to the research nurses in the ED.
Upon the ED arrival, triage nurses reevaluated the patients using the ESI algorithm to prioritize patients with higher clinical risk. Finally, research nurses recorded patients' ESI levels into the checklists.
Before embarking on the study, all EMS providers underwent a 2-h group training session held at the Tehran EMS center. They all installed the downloadable NEWS application on their smartphones and used it during the workshop to calculate the NEWS in simulated cases. The workshop was supervised by two board-certified emergency medicine physicians who were familiar with the different triage scales.
ED triage nurses evaluated the ESI level upon the patient's arrival to the ED.
In many EDs, the EMS-reported assessments and vital signs is an integral role of ED triage. In Iran, however, ED nurses rely more on their primary assessments and reevaluate all the patients regardless of the EMS providers' reports. In our ED, Triage nurses undergo regular ESI education and training. Also, their work is monitored by senior ED nurses to ensure a high-quality triage.
Thirty days after the ED arrival, research nurses reviewed the patients' medical records to identify the severe outcomes. They also followed up with the patients who were discharged from the hospital by phone call to confirm 30-day severe outcomes related to the index event.
The NEWS parameters were blood pressure (mm Hg), pulse rate ( per minute), respiratory rate (per minute), body temperature (°C), Oxygen saturation (SPO2), and level of alertness measured by AVPU (Alert, Verbal, Pain, Unresponsive).
Based on the final NEWS score, patients' clinical risk was determined as NEWS 0–4: low risk, NEWS 5–6: medium risk, and NEWS ≥ 7: high risk . In addition, patients with a high score in a single parameter (Score over 3 in any NEWS elements) were considered as low-moderate risk [25,26,27,28].
ESI algorithm is a five-level triage that categorizes the patients based on the provider's assessments. ESI levels are level 1 (Patients who require immediate life-saving intervention), Level 2 (high-risk situations, confused, lethargic, disoriented, severe pain or distress), level 3 (patients who need more than one ED resource), level 4 (patients who need one ED resource), Level 5 (patients who need zero ED resource). In addition, before allocating a patient to ESI level 3, the nurse checks the patient's vital signs (SPO2, PR, RR), and If the vital signs are abnormal, the triage nurse may upgrade the triage to ESI level 2 .
EMS providers used analog sphygmomanometers, portable pulse oximeters, and non-contact infrared digital thermometers to measure the NEWS variables. After recording these variables, they entered them into their smartphone NEWS application to calculate the final NEWS.
In the ED, nurses used their gestalt and ESI algorithm to determine the ESI levels. Also, they used a digital cardiac monitor installed in the tirage room to measure vital signs for ESI level 3 patients. The final ESI levels were recorded in the patients' triage form. Research nurses recorded these scores into their checklists. Triage nurses were blinded to the patients' NEWS scores.
The main outcome was the agreement between the prehospital NEWS and the ED ESI in detecting patients who were more likely to experience severe outcomes (NEWS ≥ 7 and ESI levels 1 and 2).
There was no similar study for comparing prehospital NEWS with ED ESI. With a presumed interclass correlation coefficient of 20% between prehospital NEWS and ED ESI in 95% of confidence interval 1418 patients were required to participate in the study. Also, the sample size required for accuracy testing, based on the assuming of 85% sensitivity for each tool, 2% of severe outcomes among transported patients in our ED, an error of 15% to estimate the sensitivity, and a type 1 error of 5%, the minimum required sample size was 1088. Therefore, based-on previous data and statistics of ED patients we estimated that three months of the ED patient flow was sufficient and near to the required sample size.
Chi-square test and Fisher test were used to compare the severe outcomes between the patients with high and medium NEWS or ESI with the patients who had low risk news or ESI. Also, to assess the amount of agreement between ESI by ED nurses and NEWS by EMS technicians, we redistributed ESI scores from five to three tiers as high risk ( ESI level 1,2), moderate risk (ESI level 3), and low risk (ESI level 4,5). Pearson correlation was used to assess the strength of the relationship between the ESI and NEWS. The prognostic properties of ESI and NEWS in terms of 30-day severe outcomes were evaluated using the receiver operating characteristic (ROC) curve. The 95% confidence interval for AUC-ROC calculated based-on the DeLong method and the test equality of AUC-ROC assessed based-on Chi-square test.. P-value < 0.05 indicated statistical significance. Analyses were performed using Stata version 15 ( StataCorp. 2017. Stata Statistical Software: Release 15. College Station, TX: StataCorp LLC).