A comparison of pediatric ocular injuries based on intention in patients admitted with trauma

Purpose Pediatric ocular trauma is a major source of morbidity and blindness and the number of epidemiological studies is incommensurate with its significance. We sought to determine differences in epidemiologic patterns of pediatric ocular injuries based on intention. Methods A retrospective review of the National Trauma Data Bank (2008–2014) was performed and patients < 21 years old, admitted with trauma and ocular injury, were identified using ICD-9CM codes. Demographic data, types of injury and external circumstances including intention were tabulated and analyzed with students’ t and chi-squared tests and logistic regression. Statistical significance was set at p < 0.05. Results Fifty-eight thousand seven hundred sixty-five pediatric patients were admitted for trauma and ocular injuries. The mean(SD) age was 11.9(6.9) years. Most patients were male (68.7%) and White (59.1%). Unintentional injuries (76.3%) were mostly associated with falls (OR = 13.4, p < 0.001), assault (16.3%) with firearms (OR = 9.15, p < 0.001) and self-inflicted trauma (0.7%) also with firearms (OR = 44.66, p < 0.001). There was increasing mean(SD) age from unintentional, 12.9(6.6) years and assault 12.3(8.1) years to self-inflicted trauma, 17(3.4) years. The 0-3 year age group had highest odds of open adnexa wounds (OR = 30.45, p < 0.001) from unintentional trauma, and traumatic brain injury (TBI) (OR = 5.77, p < 0.001) and mortality (OR = 8.52, p < 0.001) from assault. The oldest 19-21 year group, had highest odds visual pathway injuries (OR = 8.34, p < 0.001) and TBI (OR = 1.54, p = 0.048) from self-inflicted trauma and mortality (OR = 2.08, p < 0.001) from unintentional trauma. Conclusion Sight-threatening injuries were mostly associated with unintentional trauma in the youngest group and self-inflicted trauma in the oldest group. Patterns emerged of associations between demographic groups, mechanisms, types of injury and associated TBI with intention of trauma. Electronic supplementary material The online version of this article (10.1186/s12886-018-1024-7) contains supplementary material, which is available to authorized users.


Introduction
Pediatric trauma, from both accidental and intentional causes, is a leading cause of morbidity and mortality [1,2]. A recent study found that approximately 1 in 10 pediatric patients admitted for trauma in the US were assault victims [3]. In 2014, an estimated 702,000 children were physically abused [4]. These patients had three times greater risks of mortality when they had severe head injury [3]. Given its anatomic location, the eye is at risk of damage in head trauma thus ocular trauma is a significant cause of morbidity in the pediatric population [5][6][7]. Visual impairment in childhood can have marked longterm effects on daily functioning and psychosocial development [8]. The incidence of ocular injury serious enough to result in hospiatlizaion ranges from 8.85 to 15.2 per 100,000 children [9,10].
Some of the most concerning forms of ocular injuries are those attibutable to assault injuries in infants who are in an active stage of development. Epidemiology and investigations into diagnostic accuracy of ocular findings in Non-Accidental Trauma (NAT) remain active areas of research [11][12][13]. A study evaluating non-ophthalmologist accuracy in the diagnosis of retinal hemorrhages found that 13% were incorrectly documented as normal [14]. While retinal findings in NAT are widely reported, there are limited studies of other ophthalmic injuries resulting from assault [15]. Outside the ophthalmic literature, several studies have investivated the epidemiology of assault in children, comparing resulting injuries to unintentional trauma, to identify disparate patterns [1,3,[16][17][18][19]. In this study, we used a large national database to evaluate pediatric ophthalmic injuries in patients admitted for trauma in order to elucidate if specific patterns of injuries based on intention exist.

Data collection
This study is a retrospective review of the National Trauma Data Bank (NTDB) from 2008 through 2014. It was reviewed and approved by the Institutional Review Board at Montefiore Medical Center/Albert Einstein College of Medicine. The NTDB is a data bank established and maintained by the American College of Surgeons [20]. It was founded with the goals of improving the care of patients injured by trauma through epidemiological research. Over 900 centers contribute de-identified patient data voluntarily and patients meet inclusion criteria if they are either admitted to the hospital for traumatic injury or expire from injuries while in the Emergency Department. Each patient must and have been diagnosed with International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9CM) code between 800.00 and 959.9. The methods of our data collection and statistical analysis have been published in a previous publication and are summarized below [21,22].
All patients under 21 years of age, admitted for trauma with concomitant ocular injury were identified using ICD-9CM codes. The patients were subdivided by age into groups for comparative analysis. Age group brackets were chosen based on developmental milestones (0-3 years, 4-6 years, 7-11 years, 12-18 years and 19-21 years) [23,24]. Included ocular injuries were grouped depending on anatomic location. The Center for Disease Control (CDC) criteria for traumatic brain injury (TBI) was used to make this diagnosis [25,26]. The patients were further separated into groups based upon the classification of the intent of the injury they suffered -either unintentional, assault or self-inflicted.
For all included patients, we collected demographic information as well as characteristics of their injuries including the type, mechanism and intent of injury and whether the injury was blunt or penetrating. Additional patient information tabulated included the Glasgow Coma Score (GCS) (from the Emergency Department and Emergency Medical Services), Injury Severity Score (ISS), length of admission and mortality. ISS is a designation that is used to quantify the severity and extent of trauma and ranges from 0 to 75 [27]. It is calculated using assigned numerical values for injuries depending on their bodily location and severity. Higher trauma severity is indicated by higher scores and scores over 15 are classified as major trauma [27].

Statistical analysis
For continuous variables the mean, median, standard deviation (SD) and interquartile range (IQR) were calculated. Student's t-test, chi-squared test, univariate and multivariate logistic regression analysis were utilized to determine association between different variables. Odds ratio (OR) and confidence intervals (CI) were used to express relative risk. All statistical calculations were performed using SPSS software (Statistical Package for Social Science, IBM Corp, Armonk, NY) and all graphs and charts were generated in and Microsoft excel (Microsoft Corp, Redmond, WA). Patients classified as either "unknown" or "undetermined" were excluded from formal data analysis. Statistical significance was set to P < 0.05.

Unintentional trauma
This group represented the most common intention of injury. The demographic breakdowns are described in Table 1. This group was predominately male (66.5%) and most commonly in the 12-18 year age group (40.1%) (Fig. 1). White race and the 7-11 year age group were at the highest risk of this intention. The most common location was the street (50.6%) and mechanism MVTO (36.0). Only 36.8% of MVTO patients were wearing seat belts at the time of injury. Most injuries were blunt (82.9%) and the most common injuries overall were open wound of the ocular adnexa (33.0%) and orbital injuries (29.7%). Open globe injuries occurred in only 11.1% of patients. Mean (SD) was ISS 11.7(11.1) and GCS was 13.1(3.9), representing mild to moderate injury severity. TBI occurred in 53.2% and the mortality rate was 2% (Table 1).

Self-inflicted trauma
This group was by far the least common intention for pediatric ocular trauma. 80.5% were male, 68% white and 93.6%, between the ages of 12 and 21 years (Fig. 1).  With respect to injuries, orbital injuries were most likely to be unintentional in the 0-3-and 4-6 year age groups while cranial nerve injuries were more likely to be unintentional in all groups except the 0-3 year group ( Fig. 2 and Additional file 1: Table S1A). Assault injuries were more likely to result in ruptured globes in the 7-11 year group and injury to the optic nerve and pathways in the 0-3, 4-6 and 7-11 year age groups. (Fig. 2 and Additional file 1: Table S1B). Finally, self-inflicted injury was most strongly associated with injury to the optic nerve and pathways in the 12-18 and 19-21 year groups and ruptured globes in all age groups ( Fig. 2 and Additional file 1: Table S1C).

Discussion
In this study of the NTDB (2008-2014), our results reaffirm findings of previous trauma reports. There was an increasing trend in age from unintentional to assault and self-inflicted trauma with a corresponding increase in injury severity, association with and degree of traumatic brain injury (TBI), hospital stay and mortality rate (Tables 1, 2 and 3). There were strong associations between types of injuries and age groups based on intention with the younger ages suffering sight-threatening injuries, including open adnexa wounds, open globe, orbital and optic nerves and visual pathways injuries from both unintentional trauma and assault injuries while older groups had sight-threatening injuries mostly following assault-related injuries. Selfinflicted trauma showed greater association with open globe and optic nerve and visual pathway injuries in the youngest and oldest age groups respectively. There was further disparity between race and ethnicity with Whites more likely to suffer unintentional and self-inflicted trauma and Blacks and Hispanics, assault-related trauma.
Most studies addressing intention in pediatric trauma have focused on NAT in infants [12][13][14]. Several studies had focused on intention of trauma in broader pediatric ages [28][29][30][31]. In a recent study of children between 0 and 19 years, Ballesteros et al. demonstrated similar findings to our study with male and adolescent predominance and unintentional trauma outnumbering assault and selfinflicted trauma [28]. Also, they noted that the youngest children were at greatest risk of succumbing to their injuries. Blacks and Hispanics were disproportionately represented in the assault group and whites in the self-inflicted group [28]. Considering all races/ethnicities, they demonstrated a bimodal age distribution for all intentions that, in our study, was most obvious only in the assault group. These differences might have resulted from surveying different databases, over different time periods. Our data also included the 19-21 year group and had lower proportions of American Indians and Alaskan Natives. However, variance between the common demographic groups we both surveyed were borne out. Other studies who noted this race/ethnic disparity have attributed these differences to socioeconomic constraints, exposure to crime and/or suicide and limited resources [32,33].
Barampas et al. utilized the NTDB (2007-2011) to examine pediatric assault-related injuries [3]. Similarly, they found male predominance and disproportionate Black victims but also noted infants having the highest association with TBI. Although the rate of assault was slightly lower than in this study (16% vs 10%), their mortality rate of 8% was similar to our assault cohort [3]. Estroff et al. compared the epidemiology of accidental and non-accidental trauma (NAT) over four years and found that victims of NAT had a significantly higher mortality rate and injury severity [16]. These findings comport with the increased injury severity, TBI and mortality rate in the 0-3 year age group following assault injuries in our study.
While ocular injuries commonly occur in adult and pediatric patients admitted with major trauma few have reported the epidemiology of pediatric ocular trauma [34][35][36][37]. Guly et al., to our knowledge, conducted the only study of ocular injuries in major trauma that included intent in its analysis [37]. They studied patients of all ages and noted that assault resulted in 10.5% and "non-accidental injury" in 4.4% which together were slightly lower than the 16.3% we found [37]. They did not comment on the risk of mortality nor associate demographic groups, types of injury and mechanisms with intent.
Garcia et al. performed the only studies, to date, of pediatric ocular injury in major trauma [35,36]. One used the National Pediatric Trauma Registry to study 7497 patients and demonstrated strong male predominance with over 70% being victims of various vehicular accidents. This was greater than the proportion of all vehicular accidents (43.9%) in this study [35]. Again, these disparities likely reflect the different databases sourced. Our study, additionally, showed variances in trauma severity and association with TBI. Assault was associated with the highest risk of TBI and mortality in the 0-3 year group while self-inflicted trauma had the highest risk of TBI and mortality in older children. This was expected since the most common mechanism was firearms. Although there was a lower injury severity and rate of TBI, unintentional trauma was most associated with mortality in the 19-21 year group. This may have resulted from a combined MVTO and other vehicular injuries accounting for the largest group of mechanisms overall. An important finding in this study, is that amongst victims of MVTO, an alarmingly low 36.8% were wearing restraints. It has been shown that non-compliance with seatbelts leads to increased injury severity and mortality and longer hospitalizations [38][39][40]. Clearly, compliance with and enforcement of seatbelt laws is one avenue of intervention aimed at reducing pediatric ocular trauma and mortality.

Study limitations
This study had several limitations. Firstly, it was a retrospective survey of a database with multiple sources. NTDB submissions are based on data collected by Emergency Department and Trauma services and may underestimate ophthalmic injury. Also, circumstances surrounding each trauma were not available and could have clarified or helped to re-define the inexplicable self-inflicted injuries designation in the 0-3 year group. Secondly, the ICD-9CM used in this period lacked the diagnostic precision of the current ICD-10CM codes. Lastly, the results were likely skewed towards more severe injuries since all patients were admitted.

Conclusions
This study demonstrated the impact of intention of trauma on types of pediatric ocular injury, injury severity, associated TBI and mortality. While affirming previous findings of male predominance and gender and racial/ ethnic disparities, we noted that visually-threatening injuries occurred in both assault and unintentional trauma in the younger children while being more common in assault and self-inflicted injuries in older age groups. Most patients in all trauma intentions groups survived their injuries and greater injury severity and TBI were most common in infants and associated with assault and self-inflicted trauma.

Additional file
Additional file 1: