- Email: [email protected]
Bicycle-related Genitourinary Injuries
Reconstructive Urology Bicycle-related Genitourinary Injuries Marc A. Bjurlin, Lee C. Zhao, Sandra M. Goble, and Courtney M. P. Hollowell OBJECTIVE
METHODS
RESULTS
CONCLUSION
To use the National Trauma Data Bank (NTDB) to evaluate bicycling-related genitourinary (GU) injury. Bicycling is a popular recreational and competitive sport with recognized risks. GU injuries associated with bicycling is unknown. Patient cases were extracted from the NTDB, version 9.1, using the mechanism of injury Ecode for pedal cyclist and ICD-9 codes for GU injuries. The type of GU injuries, patient demographics, Injury Severity Score, surgical management, outcomes, and disposition were analyzed. Of 635,013 trauma cases evaluated, 16,585 were identified as trauma because of bicycle injury. GU injuries were sustained in 358 (2%) patients; 86% were male, with a mean age of 29 years. The most commonly injured GU organ was the kidney (75%), followed by bladder and urethra (15%), and penis and scrotum (10%). These injuries resulted in nephrectomy (0.4%), cystorrhaphy (11.3%), scrotorrhaphy (42.1%), testicular repair (3.1%), and penile repair (7.5%). Most common associated injuries included vertebral fracture (35%), pelvic fracture (25%), spleen (19%), and open head wound (15%). Patients who sustained a vertebral fracture commonly sustained a concomitant bladder and urethra (37.7%) or a renal injury (22.6%). GU injury is an infrequent occurrence with bicycle trauma, occurring in 2% of bicycle injuries, with kidneys being the most commonly injured GU organ. Physicians treating bicyclists who sustained a vertebral fracture should be aware of a possible concomitant renal or bladder injury. Young males appear to be principally at risk for GU injury. UROLOGY 78: 1187–1190, 2011. © 2011 Elsevier Inc.
A
ccording to the National Survey of Pedestrian and Bicyclists Attitudes and Behaviors sponsored by the US Department of Transportation, National Highway Traffic Safety Administration and Bureau of Transportation Statistics, approximately 57 million people—27% of the population age 16 or older— rode a bicycle at least once during the summer of 2002.1 Each year, more than 500,000 people in the United States are treated in emergency departments because of bicycle-related injuries,2 which resulted in 630 deaths in 2009 alone.3 Bicycling is 12 times more likely to lead to mortality than riding in a car.4 As a consequence, bicycle-related injuries and death are associated with costs exceeding $4 billion per year.5 Given the popularity of bicycling and its high risk of injury, bicycling-related injuries have become a significant public health issue. Most bicycle-related injury research has been restricted to local or state-level analyses, and none have specifically focused on genitourinary (GU) injuries.6,7 Moreover, This manuscript was presented at the 2010 American Urological Association Annual Meeting, Washington D.C., May 2011. From the Division of Urology, Department of Surgery, Cook County Hospital, Cook County Health and Hospitals System, Chicago, IL; Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL; and American College of Surgeons, Chicago, IL Reprint requests: Courtney M. P. Hollowell, M.D., F.A.C.S., Division of Urology, Department of Surgery, Cook County Hospital, Cook County Health and Hospitals System, 1900 W. Polk Street, Suite 465, Chicago, IL 60612. E-mail: [email protected]. Submitted: April 16, 2011, accepted (with revisions): July 9, 2011
© 2011 Elsevier Inc. All Rights Reserved
there exists a paucity of data on the scope of bicyclerelated GU injuries. The objective of our study was to examine bicycling-related GU injuries along with their surgical management and outcomes. We hypothesized that in patients who sustained a bicycle-related GU injury, rates of injury would be highest to the kidney followed by external genitalia.
MATERIAL AND METHODS A retrospective cohort design was used to conduct a study of bicycle-related GU trauma. The cohort was defined as all patients who sustained a bicycle injury (mechanism of injury was pedal cycle defined by external cause of injury codes 810.6, 811.6, 812.6, 813.6, 814.6, 815.6, 816.6, 817.6, 818.6, 819.6, 826.1) with GU injuries (International Classification of Disease, ninth revision, clinical modification code [ICD-9-CM] for kidney (866), ureter (867.2, 867.3), bladder and urethra (867.0, 867.1), penis (878.0, 878.1), and testes and scrotum (878.2, 878.3) identified in the National Trauma Data Bank (NTDB), version 9.1, and the overall incidence of these injuries was determined. The mechanism of injury defined by external cause of injury code includes any collision between a pedal cycle and a motor vehicle, animal, another pedal cycle, nonmotor road vehicle, any pedestrian, or any other object fixed, movable, or moving. The cohort also includes any entanglement in the wheel of a pedal cycle, fall from a pedal cycle, hit by an object falling or thrown on the pedal cycle, injury from an overturned pedal cycle, breakage of any part of pedal cycle, and pedal cycle not otherwise specified. The analysis included this entire cohort 0090-4295/11/$36.00 doi:10.1016/j.urology.2011.07.1386
1187
Figure 1. Age distribution of bicycle-related GU injuries.
Figure 2. Incidence of bicycle-related GU organ injury.
and was not separated into subgroup analysis. The NTDB is a voluntary data repository that currently contains the trauma admissions of participating levels I-V trauma centers throughout the United States, totaling more than 600,000 case records. The NTDB is managed by the American College of Surgeons. To provide standardization of the population, the NTDB defines trauma patients as any patient with an ICD-9-CM discharge diagnosis (800-959.9) excluding late effects of injuries (905-909), superficial injuries (910-924), and foreign body cases (930-939). All injury-related deaths in the emergency department and deaths on arrival are included in the cohort for this study. Institutional review board approval was obtained for this study. The patient cohort was analyzed, including surgical intervention, as determined by procedure code for genitourinary organs, Injury Severity Score (ISS), and concomitant injuries. The ISS is an anatomical scoring system that provides an overall score for patients with multiple injuries. Outcomes analyzed included length of hospital stay, length of stay in the intensive care unit (ICU), number of days on ventilator support, discharge disposition, and mortality. A subset analysis was performed comparing the ISS of patients who wore a protective helmet with those who did not. Abbreviated Injury Scaled (AIS)-coded renal injuries were categorized by the American Association for the Surgery of Trauma (AAST) organ injury scale and assigned a renal grade injury as previously described.8
Figure 3. Concomitant injuries.
Statistical Analysis Data were analyzed using SAS version 9.2 (Cary, NC). A P value of .05 was used to define statistical significance. Categorical variables were summarized with frequencies and percentages, and the proportion of incidents was compared between the groups using chi-square tests. Results were summarized with mean values.
RESULTS A total of 635,013 trauma cases were evaluated, and 16,585 cases were identified as trauma because of a bicycle injury. Because a single patient may sustain multiple GU injuries, there were 368 GU injuries sustained in 358 (2%) patients. Most patients were male (86%), with a mean age of 29 years. Age ranged from younger than 5 to older than 60 years old (Fig. 1). The most commonly injured GU organ was the kidney, followed by bladder and urethra, and penis and scrotum (Fig. 2). These 1188
injuries resulted in nephrectomy (0.4%), cystorrhaphy (11.3%), scrotorrhaphy (42.1%), testicular repair (3.1%), and penile repair (7.5%). Males more commonly sustained injury to the kidney (85.2 vs 14.8%, P ⬍.0001) and bladder and urethra (86.8 vs 13.2%, P ⬍.0001) compared with females. Renal injuries were assigned a renal grade injury according to the AAST: grade I 8.5%, grade II 10.4%, grade III 11.5%, grade IV 0.4%, and grade V 0.4%; 60% of the data were missing. Bicyclists who sustained renal trauma more commonly had low-grade injuries, whereas high-grade injuries were rare. Mean ISS was 12.5, ICU and hospital length of stay was 5.4 and 7.6 days, respectively, and mortality rate was 6.4%. Most commonly associated injuries included vertebral fracture, pelvic fracture, spleen wound, and open head wound (Fig. 3). Patients who sustained a vertebral fracture commonly sustained a concomitant bladder and urethral (37.7%) or renal injury (22.6%). Patients who sustained a bicycle-related GU injury were most commonly admitted to the ICU, whereas 16% required immediate surgical intervention (Table 1). Overall, 68% of patients were discharged home from the hospital without home assistance, and mortality was 6.4% (Table 1). A subset analysis was performed comparing ISS of patients who did not wear a protective helmet with those who did. No differences were noted in ISS for scores 0-8 (50% vs 52.5%), 9-15 (14.3% vs 16.3%), and 16-24 (46% vs 44%). Patients who wore a helmet tended to have a lower rate of ISS, ⬎24 (11.3% vs 44%). UROLOGY 78 (5), 2011
Table 1. Discharge disposition and mortality Disposition Emergency department disposition Floor Home ICU 24-h observation unit Telemetry Operating room Hospital discharge disposition Home with home health Home Skilled nursing facility Intermediate care facility Rehabilitation Mortality
Percent (%) 29.9 2.5 39.7 1.1 3.4 15.6 3.4 68.2 2.8 2.8 5.9 6.5
COMMENT According to the National Sporting Goods Association, 38.1 million Americans age 7 and older were estimated to have ridden a bicycle 6 times or more in 2009.9 Because of the popularity of bicycling, a high incidence of bicyclerelated injuries is observed. It is estimated that for every 2 million trips, 600 injuries will occur and 1 bicyclist will die in a crash.3 Although abrasions, lacerations, and orthopedic injuries are known risks of bicycle riding, the incidence and management of bicycle-related GU injuries is not well known. We evaluated the incidence, management, and outcomes of bicycle-related GU injuries using the NTDB. In an analysis of bicyclists injured by automobiles, Lustenberger et al found renal trauma in 1.2% of cases, similar to the incidence in the current study.10 Kim et al found in their 10-year evaluation of mountain bike– related injuries that the most common GU organ injured was the kidney (80%), followed by the ureters (8%), scrotum (8%), and testicles (4%).7 These trends were reflected in our study; however, bladder injury was not reported by Kim et al. There were no ureteric injuries in the present series, nor were there any in a French study evaluating traffic-associated GU injuries, including in cyclists.11 This does not imply that ureteral injuries are absent, but that these injuries are rare and may be subject to misdiagnosis at the time the patient is admitted for care. Although bicyclists are perhaps most often exposed to trauma of the external genital organs, patients in our study sustained a low incidence of external genital injury. The external genital organs may be at risk for injury by an upward crushing mechanism on the bony structures of the pelvis. Penile trauma has been reported to be as high as 41% in GU-related bicycle injuries.11 Furthermore, the penis and urethra may be at further risk from falls onto the bicycle frame from a straddle position. Severe scrotal trauma secondary to bike injuries has also been reported.12 In a series by Yelon et al, the 6 urological injuries in 84 cyclists who were victims of a motor vehicle UROLOGY 78 (5), 2011
accident were all urethral injuries, with no injury to the penis or scrotum.13 Impact with the bicycle handlebar, even at slow speeds, has produced renal, pancreatic, intestinal, liver, and splenic injuries. Rupture of the abdominal aorta, transection of the common bile duct, and traumatic arterial occlusion have all been reported in bicyclists.14,15 In a review of handlebar injuries in children, Clarnette and Beasley found renal contusions in 6% (2/32), urethral injuries in 9% (3/32), and lacerations involving the abdominal wall and inguino-scrotal region in 15% (5/32) of patients.16 Surgical intervention was rarely warranted in the management of bicycle-related GU injuries. Even though the kidney was the most commonly injured GU organ, it was frequently managed nonoperatively. Bicycle-related renal injuries were assigned a renal grade injury according the AAST to better translate the degree of injury into clinical practice. Bicyclists rarely sustained a grade IV or V renal injury, which may have led to the high rate of nonoperative management. However, these data must be interpreted with caution because 60% is missing. The data missing are the cases with ICD-9 codes of renal injuries that did not have an AIS submitted that corresponded to the AAST grades; or the AIS was from different versions. Moreover, methods of acquisition of AIS vary from facility to facility. Kim et al found the operative rate for renal injuries sustained while mountain biking was 5% and for the ureters was 50%.7 Scrotal and testicular injuries in their study were managed conservatively. The overall operative rate for GU injuries sustained in their study was 8%, whereas orthopedic injuries most commonly required surgical intervention (57%). Penile and scrotal injuries may often be lacerations, abrasions, or contusions, which are managed in the emergency department and the patient discharged without intervention. The current study demonstrated that vertebral fractures were the most common associated injury. Furthermore, bicyclists who sustained a vertebral fracture commonly had a concomitant bladder or renal injury. This association in injured bicyclists has not been reported previously. Kim et al found spine injuries in 12% of patients who sustained mountain biking injuries and genitourinary injuries in 2.2%.7 Physicians treating bicyclists who sustained a vertebral fracture should be aware of a possible concomitant renal or bladder injury. The mortality rate of patients who sustained bicyclerelated GU injuries was 6.4%. In 2009, cyclist deaths as a whole accounted for 2% of all US traffic fatalities and 14% of all nonoccupant traffic fatalities.3 Most of the cyclists killed were male (87%); the fatality rate for male victims was 7 times higher than that for female victims. Given the low incidence of GU injury coupled with the low rate of surgical intervention, death secondary to urological injury or subsequent urological management is rare, indicating that these injuries are not a major factor 1189
in mortality. The mortality rates in patients who sustained bicycle-related GU injuries are largely because of the associated injuries, consequent hemorrhage, and pulmonary compromise. Even though bicycle-related GU injuries may not be immediately life-threatening, they may lead to a complicated postinjury hospital course with potential for increased morbidity if not recognized early.
LIMITATIONS Although this is one of the largest studies examining bicycle-related GU injuries, there are several limitations. This study is limited in that the NTDB is not a population-based sample of hospitalized patients. It includes a disproportionate number of larger hospitals with younger and more severely injured patients. The diagnosis of bladder or urethral injury in the current study had been made by various techniques without standardization. The analysis included all GU-related pedal cycle injuries, regardless of mechanism. A subgroup analysis of different mechanisms of bicycle injuries may have further defined genitourinary injury patterns. Patients not admitted to the hospital are excluded from the NTDB; this may include injury victims who die before being transported to the hospital. Patients presenting with minor injuries manageable on an outpatient basis may have been discharged home directly from the emergency department and would not have been captured in the NTDB. The individual hospitals have different criteria, including deaths on arrival and deaths in the emergency department. Many of the variables used in injury severity are subject to measurement error, which may cause further bias between institutions. Given these limitations, this study using the NTDB has both a selection bias and an information bias. Not all trauma centers submitting data to the NTDB use the same version of the AIS and not all AIS scores correspond to AAST renal grades. Despite these limitations, the NTDB has been used successfully in multiple studies on GU trauma.17,18 The size of the cohort in this NTDB study is the largest of its kind reported in the literature to the best of our knowledge, which gives a representative incidence of GU injury, surgical management, health care resource usage, and mortality of patients who sustained a bicycle-related GU injury.
CONCLUSIONS GU injury is an infrequent occurrence in bicycle trauma, with the kidneys being the most commonly injured GU organ. Physicians treating bicyclists who sustained a vertebral fracture should be aware of a possible concomitant renal or bladder injury. Bicyclists should be aware of the
1190
low but significant risk of GU injury, especially young males who are primarily at risk. References 1. U.S. department of transportation; National Highway Traffic Safety Administration, Bureau of Transportation Statistics. National survey of pedestrian and bicyclists attitudes and behaviors. Available at: http://katana.hsrc.unc.edu/cms/downloads/ NationalSurvey_PedBikeAttitudes_Brochure2002.pdf. Accessed March 2, 2011. 2. Centers for Disease Control and Prevention. Bicycle related injuries. Available at: http://www.cdc.gov/homeandrecreationalsafety/ bikeinjuries.html. Accessed March 2, 2011. 3. National Highway Traffic Safety Administration. Traffic Safety Facts, 2009 data. Bicyclists and other cyclists. Available at: http:// www-nrd.nhtsa.dot.gov/Pubs/811386.pdf. Accessed March 7, 2011. 4. Pucher J, Dijkstra L. Promoting safe walking and cycling to improve public health: lessons from the Netherlands and Germany. Am J Public Health. 2003;93:1509-1516. 5. National Safety Council. Estimating the costs of unintentional injuries. Available at: http://www.nsc.org/news_resources/injury_ and_death_statistics/Pages/EstimatingtheCostsofUnintentional Injuries.aspx. Accessed April 1, 2011. 6. Hoffman MR, Lambert WE, Peck EG, et al. Bicycle commuter injury prevention: it is time to focus on the environment. J Trauma. 2010;69:1112-1117. 7. Kim PT, Jangra D, Ritchie AH, et al. Mountain biking injuries requiring trauma center admission: a 10-year regional trauma system experience. J Trauma. 2006;60:312-318. 8. Kuan JK, Wright JL, Nathens AB, et al. American Association for the Surgery of Trauma Organ Injury Scale for kidney injuries predicts nephrectomy, dialysis, and death in patients with blunt injury and nephrectomy for penetrating injuries. J Trauma. 2006; 60:351-356. 9. National Sporting Goods Association. Sport participation. 20022009 participation by mean age—male and female. Available at: http://www.nsga.org/files/public/2002_2009_Participationby MeanAge_Male&Female_100723.pdf. Accessed March 5, 2011. 10. Lustenberger T, Inaba K, Talving P, et al. Bicyclists injured by automobiles: relationship of age to injury type and severity—a national trauma databank analysis. J Trauma. 2010;69:1120-1125. 11. Paparel P, N’Diaye A, Laumon B, et al. The epidemiology of trauma of the genitourinary system after traffic accidents: analysis of a register of over 43,000 victims. BJU Int. 2006;97:338-341. 12. Sparnon T, Moretti K, Sach RP. BMX handlebar. A threat to manhood? Med J Aust. 1982;2:587-588. 13. Yelon JA, Harrigan N, Evans JT. Bicycle trauma: a five-year experience. Am Surg. 1995;61:202-205. 14. Acton CH, Thomas S, Clark R, et al. Bicycle incidents in children—abdominal trauma and handlebars. Med J Aust. 1994;160: 344-346. 15. Winston FK, Shaw KN, Kreshak AA, et al. Hidden spears: handlebars as injury hazards to children. Pediatrics. 1998;102:596-601. 16. Clarnette TD, Beasley SW. Handlebar injuries in children: patterns and prevention. Aust N Z J Surg. 1997;67:338-339. 17. Bjurlin MA, Fantus RJ, Mellett MM, et al. Genitourinary injuries in pelvic fracture morbidity and mortality using the National Trauma Data Bank. J Trauma. 2009;67:1033-1039. 18. Wright JL, Nathens AB, Rivara FP, et al. Renal and extrarenal predictors of nephrectomy from the national trauma data bank. J Urol. 2006;175:970-975.
UROLOGY 78 (5), 2011
METHODS
RESULTS
CONCLUSION
To use the National Trauma Data Bank (NTDB) to evaluate bicycling-related genitourinary (GU) injury. Bicycling is a popular recreational and competitive sport with recognized risks. GU injuries associated with bicycling is unknown. Patient cases were extracted from the NTDB, version 9.1, using the mechanism of injury Ecode for pedal cyclist and ICD-9 codes for GU injuries. The type of GU injuries, patient demographics, Injury Severity Score, surgical management, outcomes, and disposition were analyzed. Of 635,013 trauma cases evaluated, 16,585 were identified as trauma because of bicycle injury. GU injuries were sustained in 358 (2%) patients; 86% were male, with a mean age of 29 years. The most commonly injured GU organ was the kidney (75%), followed by bladder and urethra (15%), and penis and scrotum (10%). These injuries resulted in nephrectomy (0.4%), cystorrhaphy (11.3%), scrotorrhaphy (42.1%), testicular repair (3.1%), and penile repair (7.5%). Most common associated injuries included vertebral fracture (35%), pelvic fracture (25%), spleen (19%), and open head wound (15%). Patients who sustained a vertebral fracture commonly sustained a concomitant bladder and urethra (37.7%) or a renal injury (22.6%). GU injury is an infrequent occurrence with bicycle trauma, occurring in 2% of bicycle injuries, with kidneys being the most commonly injured GU organ. Physicians treating bicyclists who sustained a vertebral fracture should be aware of a possible concomitant renal or bladder injury. Young males appear to be principally at risk for GU injury. UROLOGY 78: 1187–1190, 2011. © 2011 Elsevier Inc.
A
ccording to the National Survey of Pedestrian and Bicyclists Attitudes and Behaviors sponsored by the US Department of Transportation, National Highway Traffic Safety Administration and Bureau of Transportation Statistics, approximately 57 million people—27% of the population age 16 or older— rode a bicycle at least once during the summer of 2002.1 Each year, more than 500,000 people in the United States are treated in emergency departments because of bicycle-related injuries,2 which resulted in 630 deaths in 2009 alone.3 Bicycling is 12 times more likely to lead to mortality than riding in a car.4 As a consequence, bicycle-related injuries and death are associated with costs exceeding $4 billion per year.5 Given the popularity of bicycling and its high risk of injury, bicycling-related injuries have become a significant public health issue. Most bicycle-related injury research has been restricted to local or state-level analyses, and none have specifically focused on genitourinary (GU) injuries.6,7 Moreover, This manuscript was presented at the 2010 American Urological Association Annual Meeting, Washington D.C., May 2011. From the Division of Urology, Department of Surgery, Cook County Hospital, Cook County Health and Hospitals System, Chicago, IL; Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL; and American College of Surgeons, Chicago, IL Reprint requests: Courtney M. P. Hollowell, M.D., F.A.C.S., Division of Urology, Department of Surgery, Cook County Hospital, Cook County Health and Hospitals System, 1900 W. Polk Street, Suite 465, Chicago, IL 60612. E-mail: [email protected]. Submitted: April 16, 2011, accepted (with revisions): July 9, 2011
© 2011 Elsevier Inc. All Rights Reserved
there exists a paucity of data on the scope of bicyclerelated GU injuries. The objective of our study was to examine bicycling-related GU injuries along with their surgical management and outcomes. We hypothesized that in patients who sustained a bicycle-related GU injury, rates of injury would be highest to the kidney followed by external genitalia.
MATERIAL AND METHODS A retrospective cohort design was used to conduct a study of bicycle-related GU trauma. The cohort was defined as all patients who sustained a bicycle injury (mechanism of injury was pedal cycle defined by external cause of injury codes 810.6, 811.6, 812.6, 813.6, 814.6, 815.6, 816.6, 817.6, 818.6, 819.6, 826.1) with GU injuries (International Classification of Disease, ninth revision, clinical modification code [ICD-9-CM] for kidney (866), ureter (867.2, 867.3), bladder and urethra (867.0, 867.1), penis (878.0, 878.1), and testes and scrotum (878.2, 878.3) identified in the National Trauma Data Bank (NTDB), version 9.1, and the overall incidence of these injuries was determined. The mechanism of injury defined by external cause of injury code includes any collision between a pedal cycle and a motor vehicle, animal, another pedal cycle, nonmotor road vehicle, any pedestrian, or any other object fixed, movable, or moving. The cohort also includes any entanglement in the wheel of a pedal cycle, fall from a pedal cycle, hit by an object falling or thrown on the pedal cycle, injury from an overturned pedal cycle, breakage of any part of pedal cycle, and pedal cycle not otherwise specified. The analysis included this entire cohort 0090-4295/11/$36.00 doi:10.1016/j.urology.2011.07.1386
1187
Figure 1. Age distribution of bicycle-related GU injuries.
Figure 2. Incidence of bicycle-related GU organ injury.
and was not separated into subgroup analysis. The NTDB is a voluntary data repository that currently contains the trauma admissions of participating levels I-V trauma centers throughout the United States, totaling more than 600,000 case records. The NTDB is managed by the American College of Surgeons. To provide standardization of the population, the NTDB defines trauma patients as any patient with an ICD-9-CM discharge diagnosis (800-959.9) excluding late effects of injuries (905-909), superficial injuries (910-924), and foreign body cases (930-939). All injury-related deaths in the emergency department and deaths on arrival are included in the cohort for this study. Institutional review board approval was obtained for this study. The patient cohort was analyzed, including surgical intervention, as determined by procedure code for genitourinary organs, Injury Severity Score (ISS), and concomitant injuries. The ISS is an anatomical scoring system that provides an overall score for patients with multiple injuries. Outcomes analyzed included length of hospital stay, length of stay in the intensive care unit (ICU), number of days on ventilator support, discharge disposition, and mortality. A subset analysis was performed comparing the ISS of patients who wore a protective helmet with those who did not. Abbreviated Injury Scaled (AIS)-coded renal injuries were categorized by the American Association for the Surgery of Trauma (AAST) organ injury scale and assigned a renal grade injury as previously described.8
Figure 3. Concomitant injuries.
Statistical Analysis Data were analyzed using SAS version 9.2 (Cary, NC). A P value of .05 was used to define statistical significance. Categorical variables were summarized with frequencies and percentages, and the proportion of incidents was compared between the groups using chi-square tests. Results were summarized with mean values.
RESULTS A total of 635,013 trauma cases were evaluated, and 16,585 cases were identified as trauma because of a bicycle injury. Because a single patient may sustain multiple GU injuries, there were 368 GU injuries sustained in 358 (2%) patients. Most patients were male (86%), with a mean age of 29 years. Age ranged from younger than 5 to older than 60 years old (Fig. 1). The most commonly injured GU organ was the kidney, followed by bladder and urethra, and penis and scrotum (Fig. 2). These 1188
injuries resulted in nephrectomy (0.4%), cystorrhaphy (11.3%), scrotorrhaphy (42.1%), testicular repair (3.1%), and penile repair (7.5%). Males more commonly sustained injury to the kidney (85.2 vs 14.8%, P ⬍.0001) and bladder and urethra (86.8 vs 13.2%, P ⬍.0001) compared with females. Renal injuries were assigned a renal grade injury according to the AAST: grade I 8.5%, grade II 10.4%, grade III 11.5%, grade IV 0.4%, and grade V 0.4%; 60% of the data were missing. Bicyclists who sustained renal trauma more commonly had low-grade injuries, whereas high-grade injuries were rare. Mean ISS was 12.5, ICU and hospital length of stay was 5.4 and 7.6 days, respectively, and mortality rate was 6.4%. Most commonly associated injuries included vertebral fracture, pelvic fracture, spleen wound, and open head wound (Fig. 3). Patients who sustained a vertebral fracture commonly sustained a concomitant bladder and urethral (37.7%) or renal injury (22.6%). Patients who sustained a bicycle-related GU injury were most commonly admitted to the ICU, whereas 16% required immediate surgical intervention (Table 1). Overall, 68% of patients were discharged home from the hospital without home assistance, and mortality was 6.4% (Table 1). A subset analysis was performed comparing ISS of patients who did not wear a protective helmet with those who did. No differences were noted in ISS for scores 0-8 (50% vs 52.5%), 9-15 (14.3% vs 16.3%), and 16-24 (46% vs 44%). Patients who wore a helmet tended to have a lower rate of ISS, ⬎24 (11.3% vs 44%). UROLOGY 78 (5), 2011
Table 1. Discharge disposition and mortality Disposition Emergency department disposition Floor Home ICU 24-h observation unit Telemetry Operating room Hospital discharge disposition Home with home health Home Skilled nursing facility Intermediate care facility Rehabilitation Mortality
Percent (%) 29.9 2.5 39.7 1.1 3.4 15.6 3.4 68.2 2.8 2.8 5.9 6.5
COMMENT According to the National Sporting Goods Association, 38.1 million Americans age 7 and older were estimated to have ridden a bicycle 6 times or more in 2009.9 Because of the popularity of bicycling, a high incidence of bicyclerelated injuries is observed. It is estimated that for every 2 million trips, 600 injuries will occur and 1 bicyclist will die in a crash.3 Although abrasions, lacerations, and orthopedic injuries are known risks of bicycle riding, the incidence and management of bicycle-related GU injuries is not well known. We evaluated the incidence, management, and outcomes of bicycle-related GU injuries using the NTDB. In an analysis of bicyclists injured by automobiles, Lustenberger et al found renal trauma in 1.2% of cases, similar to the incidence in the current study.10 Kim et al found in their 10-year evaluation of mountain bike– related injuries that the most common GU organ injured was the kidney (80%), followed by the ureters (8%), scrotum (8%), and testicles (4%).7 These trends were reflected in our study; however, bladder injury was not reported by Kim et al. There were no ureteric injuries in the present series, nor were there any in a French study evaluating traffic-associated GU injuries, including in cyclists.11 This does not imply that ureteral injuries are absent, but that these injuries are rare and may be subject to misdiagnosis at the time the patient is admitted for care. Although bicyclists are perhaps most often exposed to trauma of the external genital organs, patients in our study sustained a low incidence of external genital injury. The external genital organs may be at risk for injury by an upward crushing mechanism on the bony structures of the pelvis. Penile trauma has been reported to be as high as 41% in GU-related bicycle injuries.11 Furthermore, the penis and urethra may be at further risk from falls onto the bicycle frame from a straddle position. Severe scrotal trauma secondary to bike injuries has also been reported.12 In a series by Yelon et al, the 6 urological injuries in 84 cyclists who were victims of a motor vehicle UROLOGY 78 (5), 2011
accident were all urethral injuries, with no injury to the penis or scrotum.13 Impact with the bicycle handlebar, even at slow speeds, has produced renal, pancreatic, intestinal, liver, and splenic injuries. Rupture of the abdominal aorta, transection of the common bile duct, and traumatic arterial occlusion have all been reported in bicyclists.14,15 In a review of handlebar injuries in children, Clarnette and Beasley found renal contusions in 6% (2/32), urethral injuries in 9% (3/32), and lacerations involving the abdominal wall and inguino-scrotal region in 15% (5/32) of patients.16 Surgical intervention was rarely warranted in the management of bicycle-related GU injuries. Even though the kidney was the most commonly injured GU organ, it was frequently managed nonoperatively. Bicycle-related renal injuries were assigned a renal grade injury according the AAST to better translate the degree of injury into clinical practice. Bicyclists rarely sustained a grade IV or V renal injury, which may have led to the high rate of nonoperative management. However, these data must be interpreted with caution because 60% is missing. The data missing are the cases with ICD-9 codes of renal injuries that did not have an AIS submitted that corresponded to the AAST grades; or the AIS was from different versions. Moreover, methods of acquisition of AIS vary from facility to facility. Kim et al found the operative rate for renal injuries sustained while mountain biking was 5% and for the ureters was 50%.7 Scrotal and testicular injuries in their study were managed conservatively. The overall operative rate for GU injuries sustained in their study was 8%, whereas orthopedic injuries most commonly required surgical intervention (57%). Penile and scrotal injuries may often be lacerations, abrasions, or contusions, which are managed in the emergency department and the patient discharged without intervention. The current study demonstrated that vertebral fractures were the most common associated injury. Furthermore, bicyclists who sustained a vertebral fracture commonly had a concomitant bladder or renal injury. This association in injured bicyclists has not been reported previously. Kim et al found spine injuries in 12% of patients who sustained mountain biking injuries and genitourinary injuries in 2.2%.7 Physicians treating bicyclists who sustained a vertebral fracture should be aware of a possible concomitant renal or bladder injury. The mortality rate of patients who sustained bicyclerelated GU injuries was 6.4%. In 2009, cyclist deaths as a whole accounted for 2% of all US traffic fatalities and 14% of all nonoccupant traffic fatalities.3 Most of the cyclists killed were male (87%); the fatality rate for male victims was 7 times higher than that for female victims. Given the low incidence of GU injury coupled with the low rate of surgical intervention, death secondary to urological injury or subsequent urological management is rare, indicating that these injuries are not a major factor 1189
in mortality. The mortality rates in patients who sustained bicycle-related GU injuries are largely because of the associated injuries, consequent hemorrhage, and pulmonary compromise. Even though bicycle-related GU injuries may not be immediately life-threatening, they may lead to a complicated postinjury hospital course with potential for increased morbidity if not recognized early.
LIMITATIONS Although this is one of the largest studies examining bicycle-related GU injuries, there are several limitations. This study is limited in that the NTDB is not a population-based sample of hospitalized patients. It includes a disproportionate number of larger hospitals with younger and more severely injured patients. The diagnosis of bladder or urethral injury in the current study had been made by various techniques without standardization. The analysis included all GU-related pedal cycle injuries, regardless of mechanism. A subgroup analysis of different mechanisms of bicycle injuries may have further defined genitourinary injury patterns. Patients not admitted to the hospital are excluded from the NTDB; this may include injury victims who die before being transported to the hospital. Patients presenting with minor injuries manageable on an outpatient basis may have been discharged home directly from the emergency department and would not have been captured in the NTDB. The individual hospitals have different criteria, including deaths on arrival and deaths in the emergency department. Many of the variables used in injury severity are subject to measurement error, which may cause further bias between institutions. Given these limitations, this study using the NTDB has both a selection bias and an information bias. Not all trauma centers submitting data to the NTDB use the same version of the AIS and not all AIS scores correspond to AAST renal grades. Despite these limitations, the NTDB has been used successfully in multiple studies on GU trauma.17,18 The size of the cohort in this NTDB study is the largest of its kind reported in the literature to the best of our knowledge, which gives a representative incidence of GU injury, surgical management, health care resource usage, and mortality of patients who sustained a bicycle-related GU injury.
CONCLUSIONS GU injury is an infrequent occurrence in bicycle trauma, with the kidneys being the most commonly injured GU organ. Physicians treating bicyclists who sustained a vertebral fracture should be aware of a possible concomitant renal or bladder injury. Bicyclists should be aware of the
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low but significant risk of GU injury, especially young males who are primarily at risk. References 1. U.S. department of transportation; National Highway Traffic Safety Administration, Bureau of Transportation Statistics. National survey of pedestrian and bicyclists attitudes and behaviors. Available at: http://katana.hsrc.unc.edu/cms/downloads/ NationalSurvey_PedBikeAttitudes_Brochure2002.pdf. Accessed March 2, 2011. 2. Centers for Disease Control and Prevention. Bicycle related injuries. Available at: http://www.cdc.gov/homeandrecreationalsafety/ bikeinjuries.html. Accessed March 2, 2011. 3. National Highway Traffic Safety Administration. Traffic Safety Facts, 2009 data. Bicyclists and other cyclists. Available at: http:// www-nrd.nhtsa.dot.gov/Pubs/811386.pdf. Accessed March 7, 2011. 4. Pucher J, Dijkstra L. Promoting safe walking and cycling to improve public health: lessons from the Netherlands and Germany. Am J Public Health. 2003;93:1509-1516. 5. National Safety Council. Estimating the costs of unintentional injuries. Available at: http://www.nsc.org/news_resources/injury_ and_death_statistics/Pages/EstimatingtheCostsofUnintentional Injuries.aspx. Accessed April 1, 2011. 6. Hoffman MR, Lambert WE, Peck EG, et al. Bicycle commuter injury prevention: it is time to focus on the environment. J Trauma. 2010;69:1112-1117. 7. Kim PT, Jangra D, Ritchie AH, et al. Mountain biking injuries requiring trauma center admission: a 10-year regional trauma system experience. J Trauma. 2006;60:312-318. 8. Kuan JK, Wright JL, Nathens AB, et al. American Association for the Surgery of Trauma Organ Injury Scale for kidney injuries predicts nephrectomy, dialysis, and death in patients with blunt injury and nephrectomy for penetrating injuries. J Trauma. 2006; 60:351-356. 9. National Sporting Goods Association. Sport participation. 20022009 participation by mean age—male and female. Available at: http://www.nsga.org/files/public/2002_2009_Participationby MeanAge_Male&Female_100723.pdf. Accessed March 5, 2011. 10. Lustenberger T, Inaba K, Talving P, et al. Bicyclists injured by automobiles: relationship of age to injury type and severity—a national trauma databank analysis. J Trauma. 2010;69:1120-1125. 11. Paparel P, N’Diaye A, Laumon B, et al. The epidemiology of trauma of the genitourinary system after traffic accidents: analysis of a register of over 43,000 victims. BJU Int. 2006;97:338-341. 12. Sparnon T, Moretti K, Sach RP. BMX handlebar. A threat to manhood? Med J Aust. 1982;2:587-588. 13. Yelon JA, Harrigan N, Evans JT. Bicycle trauma: a five-year experience. Am Surg. 1995;61:202-205. 14. Acton CH, Thomas S, Clark R, et al. Bicycle incidents in children—abdominal trauma and handlebars. Med J Aust. 1994;160: 344-346. 15. Winston FK, Shaw KN, Kreshak AA, et al. Hidden spears: handlebars as injury hazards to children. Pediatrics. 1998;102:596-601. 16. Clarnette TD, Beasley SW. Handlebar injuries in children: patterns and prevention. Aust N Z J Surg. 1997;67:338-339. 17. Bjurlin MA, Fantus RJ, Mellett MM, et al. Genitourinary injuries in pelvic fracture morbidity and mortality using the National Trauma Data Bank. J Trauma. 2009;67:1033-1039. 18. Wright JL, Nathens AB, Rivara FP, et al. Renal and extrarenal predictors of nephrectomy from the national trauma data bank. J Urol. 2006;175:970-975.
UROLOGY 78 (5), 2011