Is Use of Warning Lights and Sirens Associated With Increased Risk of Ambulance Crashes? A Contemporary Analysis Using National EMS Information System (NEMSIS) Data.

STUDY OBJECTIVE: We compare reported crash rates for US ambulances responding to or transporting patients from a 911 emergency scene with or without lights and sirens. Our null hypothesis is that there will be no difference in the rate of ambulance crashes whether lights and sirens are used. METHODS: For this retrospective cohort study, we used the 2016 National EMS Information System data set to identify 911 scene responses and subsequent patient transports by transport-capable emergency medical services (EMS) units. We used the system's "response mode to scene" and "transport mode from scene" fields to determine lights and sirens use. We used the "type of response delay" and "type of transport delay" fields to identify responses and transports that were delayed because of a crash involving the ambulance. We calculated the rate of crash-related delays per 100,000 responses or transports and used multivariable logistic regression with clustered (by agency) standard errors to calculate adjusted odds ratios (AORs) (with 95% confidence intervals [CIs]) for the association between crash-related delays and lights and sirens use for responses and transports separately. RESULTS: Among 19 million included 911 scene responses, the response phase crash rate was 4.6 of 100,000 without lights and sirens and 5.4 of 100,000 with lights and sirens (AOR 1.5; 95% CI 1.2 to 1.9). For the transport phase, the crash rate was 7.0 of 100,000 without lights and sirens and 17.1 of 100,000 with lights and sirens (AOR 2.9; 95% CI 2.2 to 3.9). Excluding responses and transports with only partial lights and sirens use did not meaningfully alter the results (response AOR 1.5, 95% CI 1.2 to 1.9; transport AOR 2.8, 95% CI 2.1 to 3.8). CONCLUSION: Ambulance use of lights and sirens is associated with increased risk of ambulance crashes. The association is greatest during the transport phase. EMS providers should weigh these risks against any potential time savings associated with lights and sirens use.

Effect of mobile phone proliferation on crash notification times and fatality rates.

INTRODUCTION: The purpose of this study was to evaluate whether increased proliferation of mobile telephones has been associated with decreased MVC notification times and/or decreased MVC fatality rates in the United States (US). METHODS: We used World Bank annual mobile phone market penetration data and US Fatality Analysis Reporting System (FARS) fatal MVC data for 1994-2014. For each year, phone proliferation was measured as mobile phones per 100 population. FARS data were used to calculate MVC notification time (time EMS notified - time MVC occurred) in minutes, and to determine the MVC fatality rate per billion vehicle miles traveled (BVMT). We used basic vector auto-regression modeling to explore relationships between changes in phone proliferation and subsequent changes in median and 90th percentile MVC notification times, as well as MVC fatality rates. RESULTS: From 1994 to 2014, larger year-over-year increases in phone proliferation were associated with larger decreases in 90th percentile notification times for MVCs occurring during daylight hours (p=0.004) and on the national highway system (p=0.046) two years subsequent, and crashes off the national highway system three years subsequent (p=0.023). There were no significant associations between changes in phone proliferation and subsequent changes in median crash notification times, nor with subsequent changes in MVC fatality rates. CONCLUSION: Between 1994 and 2014 increased mobile phone proliferation in the U.S. was associated with shorter 90th percentile EMS notification times for some subgroups of fatal MVCs, but not with decreases in median notification times or overall MVC fatality rates.