During the past several decades, speed cameras have been

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1 AAST 2013 PLENARY PAPER Impact of speed cameras on trauma centers Jeffrey Skubic, DO, Steven Vanhoy, Chengcheng Hu, PhD, Nirav Patel, MD, Steven B. Johnson, MD, and Christopher Salvino, MD, Phoenix, Arizona BACKGROUND: METHODS: RESULTS: CONCLUSION: LEVEL OF EVIDENCE: KEY WORDS: While studies, mostly from Europe and Australia, have examined the effect of speed cameras on motor vehicle collisions, limited data exist regarding their impact on charges and number of patients taken to Level 1 trauma centers (L1TCs). Because of conflicting perceptions and data on their value, speed cameras were implemented along select Arizona highways in 2008 but then removed in The hypotheses of our study were twofold. (1) Speed cameras reduce admissions to L1TCs, and (2) speed cameras reduce crash kinetic energy, resulting in lower Injury Severity Score (ISS), mortality, hospital costs, and length of stay (LOS). A retrospective review of all patients admitted to L1TCs who were injured in motor vehicle crashes along a 26-mile segment of interstate I-10 in urban Phoenix was performed. Patients were identified using both the Arizona State Trauma Registry and the Arizona Department of Transportation collision data for 2009 to This specific 26-mile segment of I-10 was selected because it contained at least one speed camera within 1 mile along its entire length from October 2008 to October Two time frames were evaluated: January 1 to December 31, 2009, when cameras were in place (2009 camera group) and January 1 to December 31, 2011, when no cameras were in place (2011 no-camera group). Variables analyzed include number of collisions, number of injuries, on-scene mortality, trauma center admissions, number of collisions with admissions, inhospital mortality, ISS, hospital charges, LOS, age, sex, race, and ethnicity. Five confounding variables were eliminated. Analysis was performed using Fisher s exact test and linear regression. Camera removal was associated with a twofold increase in L1TC admissions as well as increased resource use. There were no significant differences between the two time frames for ISS, mortality, median charges, or median LOS. In this study, removal of speed cameras resulted in increased trauma center admissions and resource use. (J Trauma Acute Care Surg. 2014;77: 193Y197. Copyright * 2014 by Lippincott Williams & Wilkins) Care management study, level IV. Speed camera; resource use; collision; motor vehicle. During the past several decades, speed cameras have been implemented globally in an effort to reduce motor vehicle speed, collisions, and injuries. A key element contributing to occupant injury is kinetic energy transfer, 1 which is a function of mass and velocity (ke = 2 mv 2 ). A reduction in velocity that speed cameras may afford and the subsequent associated decrease in kinetic energy transfer may potentially decrease injury severity. The impact of speed cameras on speed reduction and injury reduction has been extensively reported overseas; however, their impact on Level 1 trauma centers (L1TCs) in the United States is unclear. Speed cameras were implemented in Arizona statewide in 2008 with the intent of reducing motor vehicle collisions (MVCs) and associated injury severity; however, because of considerable controversy, the cameras were removed in Opposition to the program included reasons such as big brother surveillance, less revenue than expected (many drivers ignored the tickets), and an accordion-like effect (decreasing velocity and then increasing velocity as one passes a camera). 3 Submitted: September 14, 2013, Revised: March 23, 2014, Accepted: April 2, From the Department of Trauma (J.S., N.P., S.B.J.), Banner Good Samaritan Regional Medical Center; Department of Trauma (C.S.), West Valley Hospital, Goodyear, Arizona; and University of Arizona, College of Medicine (S.V., C.H.), Phoenix, Arizona. This study was presented at the 72nd annual meeting of the American Association for the Surgery of Trauma, September 18Y21, 2013, in San Francisco, California. Address for reprints: Jeffrey Skubic, DO, Department of Trauma, Banner Good Samaritan Regional Medical Center, 925 E McDowell Rd, 2nd Floor, Phoenix, AZ 85006; jskubic@gmail.com. DOI: /TA This study was undertaken to examine the effect of speed cameras on L1TC resource use. PATIENTS AND METHODS After institutional review board approval was obtained, a retrospective review was performed of all motor vehicle crashes along a 20-mile bidirectional (40 miles total) segment of interstate I-10 in urban Phoenix. Two periods were examined: January 1 to December 31, 2009, while cameras were in place (camera period) and January 1 to December 31, 2011, when no cameras were in place (postcamera period). Year 2010 was excluded because cameras were removed over several months during the calendar year. Cameras were placed continuously every 2 miles over a 26-mile segment with a posted speed limit at 65 mph (experimental). Opposing traffic was separated by double-sided concrete barriers. The remaining 14 miles never had speed cameras and served as a control segment (control). Collisions were identified using the Arizona Department of Transportation collision database. 4 Admissions to L1TCs and associated patient data were identified using the Arizona State Trauma Registry. There were three L1TCs in downtown Phoenix within 1 mile from interstate I-10 during the studied periods. Variables reviewed included number of collisions, trauma center admissions, number of collisions with admissions, inhospital mortality, on-scene injuries, on-scene mortality, Injury Severity Score (ISS), hospital charges (adjusted using consumer price index), length of stay (LOS), age, sex, race, and ethnicity. 193

2 Skubic et al. Figure 1. Admissions in experimental segment. We attempted to control for five confounding key variables: traffic volume fluctuation by using our 14-mile control segment; seasonal changes (volume and weather) by using the same months of the year for each of the two periods; geographical variability by using virtually identical and colocated sections of highway as the control segment; time halo effect by excluding data that were collected from collisions, which occurred for the first 3 months after camera removal (as time haloshavebeenshowntobe2daysto8weeks); 5Y7 and variability of distance between cameras by choosing the 26-mile experimental segment, which had speed cameras at approximately 2-mile intervals. Only collisions that occurred in 2009 or 2011 within our 40-mile segment of highway were included in the study. Collisions from 2010 were excluded because the cameras were removed midway through the year. Statistical analysis was performed using Fisher s exact test and linear regression. A p G 0.05 was considered statistically significant. racing champion, who originally developed the technology to monitor his track speeds. 8 This technology used a pneumatic tube and was adapted by the Dutch police in Gatsonides company went on to invent the first speed camera in 1964; however, it was not until the 1980s that the technology was adopted by law enforcement for the purposes of speed reduction. 10 Since that time, the technology has been adapted in many partsoftheworldtoreducemotorvehiclespeeds. A Br Med J review of 14 observational studies concluded, Speed cameras are used increasinglyi however, the level of evidence is relatively poor, and most studies lack adequate comparison groups. 11 Similarly, a recent Cochrane review of 35 studies that examined the effect of speed cameras on speed, collisions, and injuries concluded that although the quality of each of the studies was moderate at best, the overall trend of all studies to report a positive reduction in these three variables was consistent. 12 Five of these studies were performed in the United States, with the remainder being largely European and Australian (speeding tolerances vary by country and driver attitudes toward speeding). 13Y17 Two of these US studies examined the number of MVCs specifically. One of these studies was conducted from 2000 to 2004 in North Carolina and reported a crash reduction of 12%. 13 These cameras were in place for only 4 months. The other study was a pilot project in Arizona. 17 Arizona has approximately 100,000 MVCs annually. These result in 750 deaths and 50,000 injuries. A total of 4,500 of these injuries are incapacitating; statewide economic loss is estimated at $2.9 billion annually. 18 Scottsdale, Arizona, implemented six speed cameras along route 101 from January 2006 to October They reported an average speed reduction of 9 mph and an average of 51% reduction in MVC and predicted that injuries from crashes would be reduced based on this. Despite a thorough analysis, the postcamera period they measured was only 1.5 months long and did not control for a time halo effect. In addition, the length of highway segment was only 6.5 miles in length. RESULTS During the 2-year period (camera [January 1 to December 31, 2009] and postcamera [January 1 to December 31, 2011]), there were 4,750 collisions in the combined 40 miles of urban highway in the experimental and control segments. Following camera removal, there was a statistically significant increase in L1TC admissions (Figs. 1 and 2). No significant corresponding increases in number of collisions, mortality, on-scene injuries, on-scene mortality, ISS, median hospital charges, or median LOS were observed (Table 1). Total hospital charges increased by $1.1 million, while total LOS increased by 146 days. DISCUSSION The world s first speed measurement device, the Gatsometer, was developed in 1958 by Maurice Gatsonides, a Monte Carlo 194 Figure 2. Admissions in control segment. * 2014 Lippincott Williams & Wilkins

3 Skubic et al. TABLE 1. Experimental and Control Data for the Two Periods Highway Segment Experimental Control Length 26 miles 14 miles Period p for Camera Cameras Present Yes No No No Effect* Collisions 1,441 2, Admissions Collisions with admission On-scene injuries On-scene mortality In-hospital mortality ISS** 4 (1Y30) 4 (1Y29) 4 (1Y26) 4.5 (1Y27) 90.1 Charge (US $1,000)** 33.3 (0.8Y1,032) 24.5 (3.1Y307.1) 21.0 (7.3Y255.1) 31.1 (4.7Y928.4) 90.1 LOS** 1.23 (0.04Y31.3) 0.97 (0Y18.2) 0.90 (0Y14.1) 0.74 (0.06Y53.6) 90.1 *The Fisher s exact test was used for count variables; linear regression was used for numerical variables (after appropriate transformation), and the test was conducted for the interaction of segment and period; logistic regression was used for binary variables, and the test was conducted for the interaction of segment and period. **Median (minimum to maximum). The findings from this study prompted Arizona to implement a statewide speed camera program. A total of 52 fixed location cameras were deployed. Signs placed 1,000 ft before the cameras read, Photo Enforcement Zone. Vehicles exceeding the posted speed limit by 11 mph were photographed and mailed a citation for US $ Projected revenue for the first year was $90 million, yet only $37 million was collected. Many drivers ignored the violation or could not be identified photographically. 2 Ultimately, the cameras were removed for reasons that remain unclear. Speed camera effects on speed, collisions, and injury severity have been studied in other countries. 19Y21 While most of these studies are largely in the United Kingdom and Australia, studies performed in the United States are scarce. This study was undertaken to assess the impact of speed cameras on L1TC admissions and resource use in the United States. While the number of collisions did not significantly increase when cameras were removed, the number of trauma admissions from MVCs doubled. ISS, mortality, median hospital charges, and median LOS did not increase, while total hospital charges and total LOS increased in accordance with the increased trauma admissions. The reason why a reduction in the number of L1TC admissions correlating with speed cameras is seen without an overall corresponding reduction in the number of collisions is unknown, but at least one possibility that is important to discuss is based on kinetic energy. Speed cameras may result in drivers going slower because of the fear of receiving citations. If speed cameras result in drivers going 9 mph less, 17 the resultant reduction in kinetic energy is 30%. This reduction in kinetic energy may be enough to decrease the number of patients requiring trauma center evaluations by the medical field personnel and subsequent admissions but not affect the overall MVC rate. Total hospital charges and total LOS increased as a result of these increased trauma admissions. If the kinetic energy is reduced as a by-product of placing fixed speed cameras, as noted earlier, why did we not see a subsequent reduction in ISS? There may be at least two reasons for the ISS not to have changed with and without cameras. First, the reduction in kinetic energy may be real and measurable but not enough to result in an actual ISS reduction. A second reason that a reduction in ISS was not seen is that what was measured did not capture total ISS. While the ISS of those patients who arrived at the L1TC showed minimal difference, the speed cameras reduced the number of persons who required admission to a L1TC. The only way to truly see if they reduced injury severity would be to record the ISS of all occupants involved in MVCs regardless of their disposition. Only those who were sent to trauma centers had a calculated ISS. Persons who went home from the scene or died on scene did not have an ISS recorded and are therefore not counted in this calculation. It may be possible that total ISS (including those going to L1TC, field deaths, and those that went home) may be different with cameras as opposed to without. Further research would need to be conducted to capture total ISS to evaluate this hypothesis. This study has several limitations. Because it is retrospective, there is no randomization. The 40 miles was chosen because of the high concentration of cameras contained, and therefore, this resulted in a selection bias. The period before speed cameras were installed was not examined for this study because only a portion of that calendar year was recorded in the Arizona State Trauma Registry, having just undergone a major rebuild at the start of While studies have examined the effects of speed cameras on reductions in speed, collisions, and injuries, none of them have looked specifically at the relationship of speed cameras and their effect on resource use in L1TC in the United States. This study evaluated a very specific and defined segment of Arizona interstate that contained speed cameras for a given period. Five critical confounding variables were eliminated in this comprehensive study looking at two periodsvwith and without fixed speed cameras. When speed cameras were removed for a 26-mile segment of the interstate highway, there was an increase in trauma admissions with an associated increase in resource use. This study has shown that the presence of fixed speed cameras in a * 2014 Lippincott Williams & Wilkins 195

4 Skubic et al. defined urban highway system can significantly reduce the number of admissions to L1TCs. AUTHORSHIP J.S. contributed to the design as well as acquisition, analysis, and interpretation of data. SV. contributed to the acquisition, analysis, and interpretation of data. C.H. contributed to the analysis and interpretation of data. N.P. contributed to the analysis and interpretation of data. S.B.J. contributed to the analysis and interpretation of data. C.S. contributed to the design as well as acquisition, analysis, and interpretation of data. ACKNOWLEDGMENT We thank Captain Jeff King from the Arizona Department of Public Safety and the Arizona Department of Transportation for their assistance with this project. DISCLOSURE The authors declare no conflicts of interest. REFERENCES 1. Richter ED, Berman T, Friedman L, Ben-David G. Speed, road injury and public health. Annu Rev Public Health. 2006;27:125Y Davenport D. Department of Public Safety Photo Enforcement Program. Office of the Auditor General of the State of Arizona ;10-02:1Y Davenport P. Arizona speed cameras will be eliminated. The Huffington Post Arizona department of transportation (AZDOT), transportation planning division, data section. Contact: Catchpole M. Years accessed: 2008Y2011. Available at: Accessed July 10, Armour M. The effect of police presence on urban driving speeds. Australian Road Research. 1984;14:142Y Hauer E, Ahlin FJ. Speed enforcement and speed choice. Accid Anal Prev. 2002;34:129Y Vaa T. Increased police enforcement: effects on speed. Accid Anal Prev. 1997;29(3):373Y Gatso History. Available at: Accessed August 8, Science in overseas industry. New Sci. 1961;265: Delaney A, Ward H, Cameron M. The history and development of speed camera use. Mohash University Research Centre. 2005;242:3,5,9, Pilkington P, Sanjay K. Effectiveness of speed cameras in preventing road traffic collisions and related casualties: systematic review. Br Med J. 2005; 330:331Y Wilson C, Willis C, Hendrikz JK, Le Brocque R, Bellamy N. Speed cameras for the prevention of road traffic injuries and deaths. Cochrane Database Syst Rev. 2010;(11):CD Cunningham CM, Hummer JE, Moon J-P. An Evaluation of the Safety Effects of Speed Enforcement Cameras in Charlotte, NC. Final report. Presented to the North Carolina Governors Highway Safety Program. Institution for Transport Research and Education. Raleigh, North Carolina: North Caroline State University; 2005:1Y Retting RA, Farmer CM, McCartt AT. Evaluation of automated speed enforcement in Montgomery County, Maryland. Insurance Institute for Highway Safety. 2008;1Y Retting RA, Farmer CM. Evaluation of Speed Camera Enforcement in the District of Columbia. Transportation Research and Education. Raleigh, North Carolina: North Carolina State University; 2005;1Y Retting RA, Kyrychenko SY, McCartt AT. Evaluation of automated speed enforcement on Loop 1010 freeway in Scottsdale, Arizona. Accid Anal Prev. 2008;40:1506Y Shin K, Washington SP, Van Schalkwyk I. Evaluation of the Scottsdale Loop 101 automated speed enforcement demonstration program. Accid Anal Prev. 2009;41:393Y Halikowski JS motor vehicle crash facts for the state of Arizona. The Arizona department of transportation intermodal transportation division Available at: index.asp. Pages 1Y Cameron MH, Newstead SV, Diamantopoulou K, Oxley P. The interaction between speed camera enforcement and speed-related mass media publicity in Victoria, Australia. 47th Annual Proceedings of the Association for the Advancement of Automotive Medicine; September 22Y24, Perez K, Mari-Dell Olmo M, Tobias A, Borrell C. Reducing road traffic injuries: effectiveness of speed cameras in an urban setting. Am J Public Health. 2007;97:1632Y Jones AP, Sauerzaph V, Haynes R. The effects of mobile speed camera introduction on road traffic crashes and casualties in a rural county of England. J Safety Res. 2008;39:101Y110. DISCUSSION Dr. Kimberly A. Davis (New Haven, Connecticut): This manuscript from Dr. Skubic and colleagues at the Banner Good Samaritan Medical Center brings us back to the debate regarding the intersection of civil rights and injury prevention. While speed cameras might seem at first to be a simple and sensible means of enforcing traffic laws they are almost always greeted by controversy, both from those who think they don t work and those who feel they violate what remains of our privacy. Manuscripts like this help to ground the debate in fact and reason. The authors found a stretch of Arizona highway that had been and then didn t have speed cameras and were able to compare the two time periods. Their results are interesting, although somewhat contradictory. They found a significant increase in the number of patients admitted to Level I trauma centers after the cameras were removed with a commensurate increase in hospital charges and resource utilization. From this one might easily conclude that the cameras were doing their job. However, as I mentioned, these data are somewhat contradictory. For example, despite the removal of cameras, there was no increase in the total number of motor vehicle collisions. Also, while the patients went to trauma centers, the average ISS of the patients didn t change. The authors conclude that the presence of cameras affected the kinetics of injury more than the number of crashes, even though a difference in injury severity was not well captured. I have several questions, related questions for the authors. First, the question that always comes up in any beforeand-after study, what else might have changed during these two time periods that might have affected your results? Since you were unable to find objective evidence of more severe injury, is it possible that a change in EMS behavior resulted in a greater number of patients evaluated at Level I trauma centers? Second, you have included data on Level I trauma center admissions but not evaluations/discharges. Given the low ISS of these cohorts there may be a number of patients evaluated and discharged from the emergency department. Do you have data on this larger denominator which includes all patients evaluated after a crash? This might shed more light on the types of injuries and volumes of patients treated during the two periods. Third, you mention the other studies that have proven decreases in average speed when cameras are in place. Do you * 2014 Lippincott Williams & Wilkins

5 Skubic et al. have any evidence that driver speed changed in your study periods, either from crash data or other means? And, finally, although you have demonstrated a difference in admissions from the segment of road that had and didn t have cameras, another segment of the same road was not associated with an increase in admissions. How do you reconcile this? In summary, the authors have demonstrated an association between the removal of speed cameras and an increase in admissions to two Level I trauma centers. Further studies of this type, however, are likely necessary to demonstrate causality. I would like to thank the Association for the privilege of the podium. Dr. Alan Cook (Dallas, Texas): If you re going to look at the efficacy would it be useful to look at deaths in the field if you re going to consider all traumas? I believe that would be a more complete analysis. Thanks. Dr. Jeff J. Skubic (Phoenix, Arizona): Thank you, again, to the AAST for the privilege of the podium. Thank you, Dr. Davis, for your excellent review, and to those who asked questions. To answer your question, could there have been any other confounders during this time period? There was no construction on the segment of highway during the time periods we evaluated. We attempted to control for the five critical variables which we felt could confound the most. And if there was some other confounder we would have thought that we would have also seen this in our control segment and we didn t. The only thing that we could say definitively was different between our experimental and control segment was that there were speed cameras in the experimental segment. For your second question, trauma evaluations, yes, actually when we said trauma admissions we meant any patient that was brought to a Level I trauma center and was evaluated. If they were discharged from the trauma bay, we still counted that as a trauma admission. Do we have any evidence of the driver speeds changing during our evaluation periods? We don t have that data. The other study I mentioned by Washington et al. did, was done in Arizona in a pilot program and they did show a reduction in speed. We specifically did not evaluate speed in our study. And the question about deaths in the field or on-scene fatalitiesvthat s an excellent question. We ve recently acquired that data as well. But we have not analyzed it yet. Thank you, again, to the AAST for the privilege of presenting our research. * 2014 Lippincott Williams & Wilkins 197