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Increased risk of injury in children with developmental disabilities
Research in Developmental Disabilities 29 (2008) 247–255
Increased risk of injury in children with developmental disabilities Li-Ching Lee a,*, Rebecca A. Harrington a, Jen Jen Chang b, Susan L. Connors c a
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA b Department of Community Health in Epidemiology, School of Public Health, Saint Louis University, Saint Louis, MO, USA c Kennedy Krieger Institute, Baltimore, MD, USA Received 12 March 2007; accepted 11 May 2007
Abstract The objective of this study was to examine injury risk in children with autism, ADD/ADHD, learning disability, psychopathology, or other medical conditions. Children aged 3–5 years who participated in the National Survey of Children’s Health were included. Six study groups were analyzed in this report: autism (n = 82), ADD/ADHD (n = 191), learning disability (n = 307), psychopathology (n = 210), other medical conditions (n = 1802), and unaffected controls (n = 13,398). The weighted prevalence of injury in each group was 24.2% (autism), 26.5% (ADD/ADHD), 9.3% (learning disability), 20.5% (psychopathology), 14.6% (other medical conditions), and 11.9% (unaffected controls). Compared to unaffected controls, the risk of injury was 2.15 (95% confidence interval (CI): 1.00–4.60), 2.74 (95% CI: 1.63–4.59), 2.06 (95% CI: 1.24–3.42), and 1.26 (95% CI: 1.00–1.58) in children with autism, ADD/ADHD, psychopathology, and other medical conditions, respectively, after adjusting for child sex, child age, number of children in the household, child race, and family poverty level. Children with autism, ADD/ADHD, and other psychopathology were about 2–3 times more likely to experience an injury that needs medical attention than unaffected controls. Future studies need to clarify the extent to which injuries in young children with autism, ADD/ADHD, and psychopathology are related to core symptoms, comorbid conditions, associated behaviors, or unintentional injuries due to lack of additional supervision from caregivers. # 2007 Elsevier Ltd. All rights reserved. Keywords: Injury; Developmental disabilities; Autism spectrum disorders; ADHD
* Corresponding author at: Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street, Room E6032, Baltimore, MD 21205, USA. Tel.: +1 410 502 0605; fax: +1 410 502 6652. E-mail address: [email protected] (L.-C. Lee). 0891-4222/$ – see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ridd.2007.05.002
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The excessive morbidity and mortality that result from injury in young children is well recognized; in fact, Healthy People 2010 lists it as a targeted health indicator for reduction (U.S. Department of Health and Human Services, 2000). In 2003, unintentional injury was the leading cause of death in children aged 3–5 in the United States (Centers for Disease Control and Prevention [CDC], 2005). Drowning, suffocation, and poisoning comprised more than 1/4 of these deaths (CDC, 2005). According to data from the National Hospital Ambulatory Medical Care Survey, the annual rate of injury-related emergency department visits was 17.8 per 100 persons per year in children 1–4 in 2004 (McCaig & Nawar, 2006). Of injury-related emergency department visits in 2004, an estimated 12.8 per 100 persons per year in the 1–4 age group were nonfatal based on data from the National Electronic Injury Surveillance System-All Injury Program (CDC, 2005). The literature consistently reports higher rates of unintentional injury in boys compared to girls (Rowe, Maughan, & Goodman, 2004; Scheidt et al., 1995; Soubhi, Raina, & Kohen, 2004). Other correlates of childhood injury reported in previous studies include younger child age, larger family size, lower level of family socio-economic status, and the child being of the white race (Pastor & Reuben, 2006; Rowe et al., 2004; Soubhi et al., 2004). Evidence indicates that children with developmental disabilities or chronic medical conditions are at a higher risk for injury or accident than are children without these conditions (Xiang, Stallones, Chen, Hostetler, & Kelleher, 2005). It has been suggested that this risk could be due to characteristics in the children that result from their disabilities, such as impaired motor control, cognitive impairments, or antisocial behavior (Leland, Garrard, & Smith, 1994; Limbos, Ramirez, Park, Peek-Asa, & Kraus, 2004; Ramirez, Peek-Asa, & Kraus, 2004; Rowe et al., 2004; Sherrard, Tonge, & Ozanne-Smith, 2001; Slayter et al., 2006). Family factors, such as poor parental supervision, are another proposed explanation for childhood injuries (Bennett Murphy, 2001; Schwebel, Hodgens, & Sterling, 2006; Soubhi et al., 2004). A recent study has shown that poor parental supervision may have played a critical role in the increased risk of injury in children with behavioral disorders (Schwebel et al., 2006). The authors reported that maternal neglect of children’s dangerous behaviors was the strongest predictor of injury in these children. Due to differences in characteristics that accompany childhood disabilities and the different family factors that may be associated, the risk of injury may vary across disability types. For example, some disorders tend to be associated with more comorbidities. Autism is an example of a disorder that commonly co-occurs with other disorders or disabilities, such as ADHD, epilepsy, cognitive impairments, or motor deficits (Canitano, 2007; Danielsson, Gillberg, Billstedt, Gillberg, & Olsson, 2005; Gurney, McPheeters, & Davis, 2006; Leyfer et al., 2006; Matson & NebelSchwalm, 2007; Rinehart et al., 2006). These comorbidities can potentially increase the risk of injury in young children if a supportive environment is not provided. Although numerous studies have reported rates of injury in individuals with intellectual disabilities in general, limited data have been reported in young children with specific developmental disabilities, with the exception of ADD/ADHD. Sherrard et al. (2001) conducted a longitudinal study in a group of intellectually challenged individuals aged 5–29 years in Australia and reported the rate of injury hospitalizations in these individuals to be twice that of the general population. Another study reported that the odds of having an accident for children with ADHD under 12 years of age were twice that of controls (Swensen et al., 2004). Although injuries in children with ADD/ADHD have been documented, the extent to which children with autism are at a higher risk of injury and accident has not previously been described in any age group. Furthermore, very few studies have been conducted to examine the link between injury and psychopathology and other medical conditions in young children. In a recent study, both
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anxiety and depression were reported to be independently associated with injury in children from the ages of 5 to 15 (Rowe et al., 2004). In addition, higher risk of injury has been reported in children with a physical or sensory disability, as well as in those with other disabilities such as an established medical disability or health impairment (Ramirez et al., 2004). The objective of the present study was to compare injury risk in children aged 3–5 with autism, ADD/ADHD, learning disability, other psychopathology, or other medical conditions, against unaffected controls from a U.S. national survey. 1. Methods 1.1. Design This study analyzed cross-sectional parent-reported data from the National Survey of Children’s Health (NSCH). The NSCH was conducted by the Centers for Disease Control and Prevention (CDC) from January 2003 to July 2004 to collect self-reported data from parents who had children aged 0–17 years across the United States (US). Although the NSCH included data from over 100,000 children, the present study only analyzed data from children 3–5 years of age. Detailed information on the development, plan, sampling, and implementation of the NSCH is described elsewhere (Blumberg et al., 2005). 1.2. Study groups Diagnoses of the following medical conditions were reported by parents responding to a series of questions on whether a doctor, health professional, teacher, or school official ever told them that their child had the following diagnoses or medical conditions: (1) autism; (2) Attention Deficit Disorder or Attention Deficit Hyperactivity Disorder (ADD or ADHD); (3) learning disability; (4) depression or anxiety problems; (5) behavioral or conduct problems; (6) asthma; (7) hearing problems or vision problems that cannot be corrected with glasses or contact lenses; (8) bone, joint, or muscle problems; and (9) diabetes. Definitions of the six study groups are described below. 1.2.1. Autism This group was defined as positive when parents responded positively to the question ‘‘Has a doctor or health professional ever told you that [CHILD] has autism?’’ Some of these children may also have parent-reported comorbidities such as ADD/ADHD, learning disability, asthma, hearing or vision problems, depression or anxiety problems, behavioral or conduct problems, bone/joint/muscle problems, or diabetes. As a result, a total of 82 children were included in this study group. Of note, we were unable to determine whether ‘‘autism’’ referred to autistic disorder or autism spectrum disorders due to the way this question was phrased. 1.2.2. ADD/ADHD This group was defined as positive when parents responded positively to the question ‘‘Has a doctor or health professional ever told you that [CHILD] has Attention Deficit Disorder or Attention Deficit Hyperactivity Disorder, that is, ADD or ADHD?’’ Similar to the autism case group, children in this group may have other diagnoses as listed above, with the exception of autism. Consequently, 191 children were included in this study group.
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1.2.3. Learning disability Children whose parents responded positively to the question ‘‘Has a doctor, health professional, teacher, or school official ever told you [CHILD] has a learning disability?’’ Children in this study group (n = 307) may have other diagnoses as listed above from (4) to (8) but not autism or ADD/ADHD. 1.2.4. Psychopathology This study group includes children whose parents have ever been told by a doctor or health professional that their child has either depression or anxiety problems, or behavioral or conduct problems. Children in this group may have the comorbidities listed above from (5) to (8) but not autism, ADD/ADHD, or learning disability. As a result, 210 children were categorized in this study group. 1.2.5. Other medical conditions This study group includes 1802 children who had parent-reported asthma, hearing/vision problems, bone/joint/muscle problems, or diabetes but not any of the conditions listed above from (1) to (5). 1.2.6. Unaffected controls This comparison group comprised children without parent-reported disabilities or medical conditions as listed above from (1) to (8). The number of children included in this study group is 13,398. 1.3. Outcome variable 1.3.1. Injury This variable was coded as positive if parents reported ‘yes’ to any of the following situations: during the past 12 months, (1) [CHILD] went to a hospital emergency room because of an accident, injury, or poisoning; (2) [CHILD] has been injured and required medical attention; or (3) [CHILD] has been poisoned by accident and required medical attention. Medical attention as defined here was ‘‘not limited to emergency room visits, or attention that requires a doctor. This includes situations where the parent is able to provide the medical attention themselves, or where a call is placed to a poison control center, but the care is administered by the parent, etc.’’ 1.4. Statistical analysis Bivariate (unadjusted) and multivariate (adjusted) regression analyses were performed to compare injury (yes/no) during the past 12 months in children with medical conditions (i.e. autism, ADD/ADHD, learning disability, psychopathology, and other medical conditions) to unaffected controls. Specifically, each of the five case groups was compared to the control group separately. Methods of variance estimation accounted for the complex sample design (i.e. multistage sampling) with weighting. Standard errors were obtained using the Taylor-series approximation method in both bivariate and multivariate analyses. Logistic regression modeling with survey command was performed and odds ratios (OR) with 95% confidence intervals (CI) were presented. Demographic characteristics such as child sex, child age, number of children in the household, child race, and family poverty level were included as confounding variables and were adjusted for in the multivariate logistic regression models.
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In order to obtain a population-based estimate, a sampling weight was assigned to each child for whom an interview was completed. The sampling weight was made of various adjustments, including nonresponse and total number of phone lines within the household. Furthermore, the sampling weights were post-stratified so that the sum of sampling weights of participating children was equal to the number of all eligible children in the State. The total number of children in each State was determined based on US Census 2000. Detailed information about sampling and weighting procedures in NSCH can be found in Blumberg et al. (2005). 2. Results The un-weighted and weighted 12-month prevalence of injury by study groups are presented in Table 1. Briefly, the prevalence in the autism group, the ADD/ADHD group, and the psychopathology groups were approximately twice that of the unaffected controls. Specifically, the weighted prevalence of injury was 24.2% in the autism group, 26.5% in the ADD/ADHD group, and 20.5% in the psychopathology group. It was about 12% in the unaffected control group. Bivariate analysis, where confounding variables were not adjusted, indicated that the odds of injury for children with autism and ADD/ADHD were more than two-fold greater compared to unaffected controls, with an unadjusted odds ratio (OR) of 2.36 (95% CI: 1.11–5.00) for the autism group, and 2.66 (95% CI: 1.60–4.40) for the ADD/ADHD group (Table 2). Children with psychopathology or other medical conditions also had greater likelihood of injury with an OR of 1.91 (95% CI: 1.16–3.14) and 1.26 (95% CI: 1.02–1.56), respectively, compared to unaffected controls. Males were 1.30 times more likely to have had an injury compared to females. The odds of injury for children in the ‘‘others’’ race category (non-white) was 12% less than the odds in white children. There was no statistically significant association between risk of injury and a child’s age, the number of children in the household, or household poverty. The adjusted odds ratios, shown in Table 3, indicated that factors such as child sex, child age, number of children in the household, child race, and family poverty level cannot explain the increased risk of injury in children with autism, ADD/ADHD, learning disability, psychopathology, or other medical conditions. Children with autism, ADD/ADHD, or psychopathology were twice as likely to have had an injury as the unaffected controls, after controlling for these confounding variables. The adjusted ORs for the autism, ADD/ADHD, and psychopathology groups were 2.15 (95% CI: 1.00–4.60), 2.74 (95% CI: 1.63–4.59), and 2.06 (95% CI: 1.24–3.42), respectively. Although the adjusted OR in children with other medical conditions also reached statistical significance, 95% CI: 1.00–1.58, the magnitude of the OR (1.26) was not as great as those for the autism, ADD/ADHD, or psychopathology groups.
Table 1 Un-weighted and weighted 12-month prevalence of injury by study groups
Autism ADD/ADHD Learning disability Psychopathology Other medical conditions Unaffected controls
Un-weighted (%)
Weighted (%)
20.7 23.0 16.6 23.3 17.0 12.2
24.2 26.5 9.3 20.5 14.6 11.9
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Table 2 Unadjusted associations between children with disabilities or medical conditions and risk of injury Injury—un-weighted
Injury—weighted
Yes, n (%)
No, n (%)
Yes (%)
No (%)
OR
95% CI
Study group Autism ADD/ADHD Learning disability Psychopathology Other medical conditions Typical controls
17 44 51 49 307 1633
65 147 256 161 1494 11762
(0.5) (1.1) (1.8) (1.2) (10.8) (84.7)
0.8 2.5 1.5 2.3 13.7 79.2
0.3 1.0 2.1 1.3 11.5 83.8
2.36 2.66 0.75 1.91 1.26 1.00
1.11, 1.60, 0.49, 1.16, 1.02, Ref
Child’s sex Male Female
1216 (56.2) 947 (43.8)
7126 (50.2) 7056 (49.8)
57.5 42.5
51.1 48.9
1.30 1.00
1.11, 1.51 Ref
Child’s age (years) 3 4 5
788 (36.4) 738 (34.1) 638 (29.5)
4902 (34.5) 4693 (33.1) 4595 (32.4)
34.4 34.4 31.2
33.1 34.4 32.5
1.08 1.04 1.00
0.90, 1.31 0.85, 1.28 Ref
# of children in the household 1 2 3+
731 (33.8) 902 (41.7) 531 (24.5)
4904 (34.6) 6048 (42.6) 3238 (22.8)
18.9 40.9 40.2
17.8 41.2 41.0
1.00 0.94 0.92
Ref 0.79, 1.10 0.76, 1.12
1667 (81.8) 370 (18.2)
10203 (78.4) 2818 (21.6)
78.4 21.6
74.0 26.0
1.00 0.78
Ref 0.62, 0.99
14.6 18.3 20.2 37.7 9.2
16.7 18.2 18.5 35.4 11.1
0.82 0.94 1.03 1.00 0.78
0.63, 0.75, 0.85, Ref 0.55,
Child race White Others Household’s poverty levela <100% 100–184% 185–299% 300% Missing
264 356 476 903 165
(0.8) (2.1) (2.4) (2.3) (14.6) (77.7)
(12.2) (16.5) (22.0) (41.7) (7.6)
1742 2333 3014 5769 1332
(12.3) (16.4) (21.2) (40.7) (9.4)
5.00 4.40 1.16 3.14 1.56
1.05 1.20 1.23 1.10
a
The percentage of poverty level was derived by comparing the income-to-household-size measure against DHHS Federal Poverty Guidelines. A detailed description of the development of this poverty indicator is available in Blumberg et al. (2005).
Table 3 Adjusted associations between children with disabilities or medical conditions and risk of injury
Autism ADD/ADHD Learning disability Psychopathology Other medical conditions Unaffected controls
ORadj
95% CI
2.15 2.74 0.78 2.06 1.26 1.00
1.00, 1.63, 0.50, 1.24, 1.00, Ref
4.60 4.59 1.22 3.42 1.58
Note: Multivariate regression model adjusted for child sex, child age, number of children in the household, child race, and family poverty level.
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3. Discussion Findings from this study indicated that children with autism, ADD/ADHD, and other psychopathology were about two to three times more likely to experience an injury or accident that needs medical attention compared to unaffected controls. Consistent with results from Sherrard, Tonge, and Ozanne-Smith (2002), where the study sample had a wider age range (5–29 years), we found that social and family factors had minimal effect on the risk of injury. Based on previous literature, it is not surprising that the ADD/ADHD group appeared to have the highest risk of injury among the case groups (i.e., autism, ADD/ADHD, learning disability, psychopathology, and other medical conditions) and the control group (Pastor & Reuben, 2006; Swensen et al., 2004; Xiang et al., 2005). The finding that children with autism are at higher risk for injury supports the previously described hypothesis and is an association that has not been examined in a comparative study prior to this report. Whether the increased risk in children with autism is due to sensorimotor deficits or behavioral abnormalities, including hyperactivity, social avoidance, and poor judgment remains a question. These findings need to be considered within the context of the parent-reported data, and the cross-sectional study design. The fact that diagnoses of the children (e.g. autism, ADD/ADHD, learning disability, etc.) were obtained from parent report and were not validated by clinicians is the main limitation of our study. Because of this, there could be some misreporting of diagnoses. In addition, the injury questions included in NSCH did not specify whether they were intentional, unintentional, or disease/medical condition related, and we were unable to determine whether the increased risk was due to environmental factors (e.g. inadequate safety in the home or childcare setting, lack of parental supervision), symptoms of comorbid conditions (e.g. seizures), or associated behaviors (e.g. self-injury). Information bias is also possible if parents of children with developmental disabilities or medical conditions systematically reported injuries differently than parents of typically developing children. Furthermore, parents of children with developmental disabilities or medical conditions may be more likely to request medical attention when an injury happens to their child. For example, parents of children who are hyperactive, such as those with the diagnoses of ADD/ADHD or autism, may be more vigilant than parents of typically developing children. Through experiences with previous injuries these parents may tend to request medical attention more quickly or more often than other parents. Another example is that many children with autism do not respond to pain in a typical manner. Parents of those children may also be more apt to seek medical attention, knowing this characteristic of their child. Nevertheless, this study utilized data from a nationally representative sample with large numbers in the study groups, especially the case groups, which provides sufficient statistical power to examine injury in children with developmental disabilities and medical conditions during early childhood. The implications from this study are that parents, caretakers, and educational personnel involved with young children with autism, ADD/ADHD, or other psychopathology should receive additional education on injury and accident prevention. Injury prevention needs to be emphasized in order to reduce the excess incidence of injury in children with developmental disabilities and medical conditions. In addition, both general pediatricians and specialists (e.g., pediatric neurologists, psychiatrists, and psychologists) should be aware of the increased potential for injury in children with autism, ADD/ADHD or other psychopathology, in order to contribute to the education and awareness of parents, caretakers, and school personnel. Although parents or caregivers of children with developmental disabilities might be aware of the greater risk documented in this study, it may be difficult for them to quickly detect the severity of an
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injury in children whose disability is accompanied by a decreased ability to communicate and socially interact. Heightened awareness, detailed histories, and a lower threshold at which to conduct a thorough exam and/or imaging and laboratory testing may be necessary in this situation. In order to determine the prevention efforts that would be most effective, future studies need to clarify the extent to which injuries in young children with autism, ADD/ADHD, and psychopathology are related to (1) core symptoms and/or comorbid conditions (e.g., seizures or sensorimotor deficits), (2) associated behaviors (e.g., self injury), or (3) unintentional injuries due to factors such as lack of sufficient attention from caregivers. Acknowledgment Li-Ching Lee’s and Rebecca A. Harrington’s effort was supported by CDC cooperative agreement U10/CCU320408-05. A preliminary version of this paper was presented in part at the Second North American Congress of Epidemiology, Seattle, Washington, US, June 21–24, 2006. The analyses, interpretations, and conclusion addressed in this publication are the authors’ responsibility and are not a representation of the National Center for Health Statistics’ opinion. References Bennett Murphy, L. M. (2001). Adolescent mothers’ beliefs about parenting and injury prevention: Results of a focus group. Journal of Pediatric Health Care, 15, 194–199. Blumberg, S., Olson, L., Frankel, M., Osborn, L., Srinath, K., & Giambo, P. (2005). Design and operation of the national survey of children’s health, 2003. National Center for Health Statistics: Vital and Health Statistics 1. Canitano, R. (2007). Epilepsy in autism spectrum disorders. European Child & Adolescent Psychiatry, 16, 161–166. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. (2005). Web-based injury statistics query and reporting system (WISQARS). Retrieved November 15, 2006, from www.cdc.gov/ncipc/wisqars Danielsson, S., Gillberg, I. C., Billstedt, E., Gillberg, C., & Olsson, I. (2005). Epilepsy in young adults with autism: A prospective population-based follow-up study of 120 individuals diagnosed in childhood. Epilepsia, 46, 918–923. Gurney, J. G., McPheeters, M. L., & Davis, M. M. (2006). Parental report of health conditions and health care use among children with and without autism: National survey of children’s health. Archives of Pediatrics & Adolescent Medicine, 160, 825–830. Leland, N. L., Garrard, J., & Smith, D. K. (1994). Comparison of injuries to children with and without disabilities in a daycare center. Journal of Developmental and Behavioral Pediatrics, 15, 402–408. Leyfer, O. T., Folstein, S. E., Bacalman, S., Davis, N. O., Dinh, E., Morgan, J., et al. (2006). Comorbid psychiatric disorders in children with autism: Interview development and rates of disorders. Journal of Autism and Developmental Disorders, 36, 849–861. Limbos, M. A., Ramirez, M., Park, L. S., Peek-Asa, C., & Kraus, J. F. (2004). Injuries to the head among children enrolled in special education. Archives of Pediatrics & Adolescent Medicine, 158, 1057–1061. Matson, J. L., & Nebel-Schwalm, M. S. (2007). Comorbid psychopathology with autism spectrum disorder in children: An overview. Research in Developmental Disabilities, 28, 341–352. McCaig, L. F., & Nawar, E. N. (2006). National hospital ambulatory medical care survey: 2004 emergency department summary. Advance data from vital and health statistics; no 372, Hyattsville, MD: National Center for Health Statistics. Pastor, P. N., & Reuben, C. A. (2006). Identified attention-deficit/hyperactivity disorder and medically attended, nonfatal injuries: US school-age children, 1997–2002. Ambulatory Pediatrics, 6, 38–44. Ramirez, M., Peek-Asa, C., & Kraus, J. F. (2004). Disability and risk of school related injury. Injury Prevention, 10, 21–26. Rinehart, N. J., Tonge, B. J., Bradshaw, J. L., Iansek, R., Enticott, P. G., & McGinley, J. (2006). Gait function in highfunctioning autism and asperger’s disorder: Evidence for basal-ganglia and cerebellar involvement? European Child & Adolescent Psychiatry, 15, 256–264. Rowe, R., Maughan, B., & Goodman, R. (2004). Childhood psychiatric disorder and unintentional injury: Findings from a national cohort study. Journal of Pediatric Psychology, 29, 119–130. Scheidt, P. C., Harel, Y., Trumble, A. C., Jones, D. H., Overpeck, M. D., & Bijur, P. E. (1995). The epidemiology of nonfatal injuries among US children and youth. American Journal of Public Health, 85, 932–938.
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Schwebel, D. C., Hodgens, J. B., & Sterling, S. (2006). How mothers parent their children with behavior disorders: Implications for unintentional injury risk. Journal of Safety Research, 37, 167–173. Sherrard, J., Tonge, B. J., & Ozanne-Smith, J. (2001). Injury in young people with intellectual disability: Descriptive epidemiology. Injury Prevention, 7, 56–61. Sherrard, J., Tonge, B. J., & Ozanne-Smith, J. (2002). Injury risk in young people with intellectual disability. Journal of Intellectual Disability Research, 46, 6–16. Slayter, E. M., Garnick, D. W., Kubisiak, J. M., Bishop, C. E., Gilden, D. M., & Hakim, R. B. (2006). Injury prevalence among children and adolescents with mental retardation. Mental Retardation, 44, 212–223. Soubhi, H., Raina, P., & Kohen, D. (2004). Neighborhood, family, and child predictors of childhood injury in Canada. American Journal of Health Behavior, 28, 397–409. Swensen, A., Birnbaum, H. G., Ben Hamadi, R., Greenberg, P., Cremieux, P. Y., & Secnik, K. (2004). Incidence and costs of accidents among attention-deficit/hyperactivity disorder patients. The Journal of Adolescent Health, 35, 346.e1– 346.e9. U.S. Department of Health and Human Services. (2000). Healthy people 2010: Understanding and improving health. Washington, DC: US Government Printing Office. Xiang, H., Stallones, L., Chen, G., Hostetler, S. G., & Kelleher, K. (2005). Nonfatal injuries among US children with disabling conditions. American Journal of Public Health, 95, 1970–1975.
Increased risk of injury in children with developmental disabilities Li-Ching Lee a,*, Rebecca A. Harrington a, Jen Jen Chang b, Susan L. Connors c a
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA b Department of Community Health in Epidemiology, School of Public Health, Saint Louis University, Saint Louis, MO, USA c Kennedy Krieger Institute, Baltimore, MD, USA Received 12 March 2007; accepted 11 May 2007
Abstract The objective of this study was to examine injury risk in children with autism, ADD/ADHD, learning disability, psychopathology, or other medical conditions. Children aged 3–5 years who participated in the National Survey of Children’s Health were included. Six study groups were analyzed in this report: autism (n = 82), ADD/ADHD (n = 191), learning disability (n = 307), psychopathology (n = 210), other medical conditions (n = 1802), and unaffected controls (n = 13,398). The weighted prevalence of injury in each group was 24.2% (autism), 26.5% (ADD/ADHD), 9.3% (learning disability), 20.5% (psychopathology), 14.6% (other medical conditions), and 11.9% (unaffected controls). Compared to unaffected controls, the risk of injury was 2.15 (95% confidence interval (CI): 1.00–4.60), 2.74 (95% CI: 1.63–4.59), 2.06 (95% CI: 1.24–3.42), and 1.26 (95% CI: 1.00–1.58) in children with autism, ADD/ADHD, psychopathology, and other medical conditions, respectively, after adjusting for child sex, child age, number of children in the household, child race, and family poverty level. Children with autism, ADD/ADHD, and other psychopathology were about 2–3 times more likely to experience an injury that needs medical attention than unaffected controls. Future studies need to clarify the extent to which injuries in young children with autism, ADD/ADHD, and psychopathology are related to core symptoms, comorbid conditions, associated behaviors, or unintentional injuries due to lack of additional supervision from caregivers. # 2007 Elsevier Ltd. All rights reserved. Keywords: Injury; Developmental disabilities; Autism spectrum disorders; ADHD
* Corresponding author at: Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street, Room E6032, Baltimore, MD 21205, USA. Tel.: +1 410 502 0605; fax: +1 410 502 6652. E-mail address: [email protected] (L.-C. Lee). 0891-4222/$ – see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ridd.2007.05.002
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The excessive morbidity and mortality that result from injury in young children is well recognized; in fact, Healthy People 2010 lists it as a targeted health indicator for reduction (U.S. Department of Health and Human Services, 2000). In 2003, unintentional injury was the leading cause of death in children aged 3–5 in the United States (Centers for Disease Control and Prevention [CDC], 2005). Drowning, suffocation, and poisoning comprised more than 1/4 of these deaths (CDC, 2005). According to data from the National Hospital Ambulatory Medical Care Survey, the annual rate of injury-related emergency department visits was 17.8 per 100 persons per year in children 1–4 in 2004 (McCaig & Nawar, 2006). Of injury-related emergency department visits in 2004, an estimated 12.8 per 100 persons per year in the 1–4 age group were nonfatal based on data from the National Electronic Injury Surveillance System-All Injury Program (CDC, 2005). The literature consistently reports higher rates of unintentional injury in boys compared to girls (Rowe, Maughan, & Goodman, 2004; Scheidt et al., 1995; Soubhi, Raina, & Kohen, 2004). Other correlates of childhood injury reported in previous studies include younger child age, larger family size, lower level of family socio-economic status, and the child being of the white race (Pastor & Reuben, 2006; Rowe et al., 2004; Soubhi et al., 2004). Evidence indicates that children with developmental disabilities or chronic medical conditions are at a higher risk for injury or accident than are children without these conditions (Xiang, Stallones, Chen, Hostetler, & Kelleher, 2005). It has been suggested that this risk could be due to characteristics in the children that result from their disabilities, such as impaired motor control, cognitive impairments, or antisocial behavior (Leland, Garrard, & Smith, 1994; Limbos, Ramirez, Park, Peek-Asa, & Kraus, 2004; Ramirez, Peek-Asa, & Kraus, 2004; Rowe et al., 2004; Sherrard, Tonge, & Ozanne-Smith, 2001; Slayter et al., 2006). Family factors, such as poor parental supervision, are another proposed explanation for childhood injuries (Bennett Murphy, 2001; Schwebel, Hodgens, & Sterling, 2006; Soubhi et al., 2004). A recent study has shown that poor parental supervision may have played a critical role in the increased risk of injury in children with behavioral disorders (Schwebel et al., 2006). The authors reported that maternal neglect of children’s dangerous behaviors was the strongest predictor of injury in these children. Due to differences in characteristics that accompany childhood disabilities and the different family factors that may be associated, the risk of injury may vary across disability types. For example, some disorders tend to be associated with more comorbidities. Autism is an example of a disorder that commonly co-occurs with other disorders or disabilities, such as ADHD, epilepsy, cognitive impairments, or motor deficits (Canitano, 2007; Danielsson, Gillberg, Billstedt, Gillberg, & Olsson, 2005; Gurney, McPheeters, & Davis, 2006; Leyfer et al., 2006; Matson & NebelSchwalm, 2007; Rinehart et al., 2006). These comorbidities can potentially increase the risk of injury in young children if a supportive environment is not provided. Although numerous studies have reported rates of injury in individuals with intellectual disabilities in general, limited data have been reported in young children with specific developmental disabilities, with the exception of ADD/ADHD. Sherrard et al. (2001) conducted a longitudinal study in a group of intellectually challenged individuals aged 5–29 years in Australia and reported the rate of injury hospitalizations in these individuals to be twice that of the general population. Another study reported that the odds of having an accident for children with ADHD under 12 years of age were twice that of controls (Swensen et al., 2004). Although injuries in children with ADD/ADHD have been documented, the extent to which children with autism are at a higher risk of injury and accident has not previously been described in any age group. Furthermore, very few studies have been conducted to examine the link between injury and psychopathology and other medical conditions in young children. In a recent study, both
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anxiety and depression were reported to be independently associated with injury in children from the ages of 5 to 15 (Rowe et al., 2004). In addition, higher risk of injury has been reported in children with a physical or sensory disability, as well as in those with other disabilities such as an established medical disability or health impairment (Ramirez et al., 2004). The objective of the present study was to compare injury risk in children aged 3–5 with autism, ADD/ADHD, learning disability, other psychopathology, or other medical conditions, against unaffected controls from a U.S. national survey. 1. Methods 1.1. Design This study analyzed cross-sectional parent-reported data from the National Survey of Children’s Health (NSCH). The NSCH was conducted by the Centers for Disease Control and Prevention (CDC) from January 2003 to July 2004 to collect self-reported data from parents who had children aged 0–17 years across the United States (US). Although the NSCH included data from over 100,000 children, the present study only analyzed data from children 3–5 years of age. Detailed information on the development, plan, sampling, and implementation of the NSCH is described elsewhere (Blumberg et al., 2005). 1.2. Study groups Diagnoses of the following medical conditions were reported by parents responding to a series of questions on whether a doctor, health professional, teacher, or school official ever told them that their child had the following diagnoses or medical conditions: (1) autism; (2) Attention Deficit Disorder or Attention Deficit Hyperactivity Disorder (ADD or ADHD); (3) learning disability; (4) depression or anxiety problems; (5) behavioral or conduct problems; (6) asthma; (7) hearing problems or vision problems that cannot be corrected with glasses or contact lenses; (8) bone, joint, or muscle problems; and (9) diabetes. Definitions of the six study groups are described below. 1.2.1. Autism This group was defined as positive when parents responded positively to the question ‘‘Has a doctor or health professional ever told you that [CHILD] has autism?’’ Some of these children may also have parent-reported comorbidities such as ADD/ADHD, learning disability, asthma, hearing or vision problems, depression or anxiety problems, behavioral or conduct problems, bone/joint/muscle problems, or diabetes. As a result, a total of 82 children were included in this study group. Of note, we were unable to determine whether ‘‘autism’’ referred to autistic disorder or autism spectrum disorders due to the way this question was phrased. 1.2.2. ADD/ADHD This group was defined as positive when parents responded positively to the question ‘‘Has a doctor or health professional ever told you that [CHILD] has Attention Deficit Disorder or Attention Deficit Hyperactivity Disorder, that is, ADD or ADHD?’’ Similar to the autism case group, children in this group may have other diagnoses as listed above, with the exception of autism. Consequently, 191 children were included in this study group.
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1.2.3. Learning disability Children whose parents responded positively to the question ‘‘Has a doctor, health professional, teacher, or school official ever told you [CHILD] has a learning disability?’’ Children in this study group (n = 307) may have other diagnoses as listed above from (4) to (8) but not autism or ADD/ADHD. 1.2.4. Psychopathology This study group includes children whose parents have ever been told by a doctor or health professional that their child has either depression or anxiety problems, or behavioral or conduct problems. Children in this group may have the comorbidities listed above from (5) to (8) but not autism, ADD/ADHD, or learning disability. As a result, 210 children were categorized in this study group. 1.2.5. Other medical conditions This study group includes 1802 children who had parent-reported asthma, hearing/vision problems, bone/joint/muscle problems, or diabetes but not any of the conditions listed above from (1) to (5). 1.2.6. Unaffected controls This comparison group comprised children without parent-reported disabilities or medical conditions as listed above from (1) to (8). The number of children included in this study group is 13,398. 1.3. Outcome variable 1.3.1. Injury This variable was coded as positive if parents reported ‘yes’ to any of the following situations: during the past 12 months, (1) [CHILD] went to a hospital emergency room because of an accident, injury, or poisoning; (2) [CHILD] has been injured and required medical attention; or (3) [CHILD] has been poisoned by accident and required medical attention. Medical attention as defined here was ‘‘not limited to emergency room visits, or attention that requires a doctor. This includes situations where the parent is able to provide the medical attention themselves, or where a call is placed to a poison control center, but the care is administered by the parent, etc.’’ 1.4. Statistical analysis Bivariate (unadjusted) and multivariate (adjusted) regression analyses were performed to compare injury (yes/no) during the past 12 months in children with medical conditions (i.e. autism, ADD/ADHD, learning disability, psychopathology, and other medical conditions) to unaffected controls. Specifically, each of the five case groups was compared to the control group separately. Methods of variance estimation accounted for the complex sample design (i.e. multistage sampling) with weighting. Standard errors were obtained using the Taylor-series approximation method in both bivariate and multivariate analyses. Logistic regression modeling with survey command was performed and odds ratios (OR) with 95% confidence intervals (CI) were presented. Demographic characteristics such as child sex, child age, number of children in the household, child race, and family poverty level were included as confounding variables and were adjusted for in the multivariate logistic regression models.
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In order to obtain a population-based estimate, a sampling weight was assigned to each child for whom an interview was completed. The sampling weight was made of various adjustments, including nonresponse and total number of phone lines within the household. Furthermore, the sampling weights were post-stratified so that the sum of sampling weights of participating children was equal to the number of all eligible children in the State. The total number of children in each State was determined based on US Census 2000. Detailed information about sampling and weighting procedures in NSCH can be found in Blumberg et al. (2005). 2. Results The un-weighted and weighted 12-month prevalence of injury by study groups are presented in Table 1. Briefly, the prevalence in the autism group, the ADD/ADHD group, and the psychopathology groups were approximately twice that of the unaffected controls. Specifically, the weighted prevalence of injury was 24.2% in the autism group, 26.5% in the ADD/ADHD group, and 20.5% in the psychopathology group. It was about 12% in the unaffected control group. Bivariate analysis, where confounding variables were not adjusted, indicated that the odds of injury for children with autism and ADD/ADHD were more than two-fold greater compared to unaffected controls, with an unadjusted odds ratio (OR) of 2.36 (95% CI: 1.11–5.00) for the autism group, and 2.66 (95% CI: 1.60–4.40) for the ADD/ADHD group (Table 2). Children with psychopathology or other medical conditions also had greater likelihood of injury with an OR of 1.91 (95% CI: 1.16–3.14) and 1.26 (95% CI: 1.02–1.56), respectively, compared to unaffected controls. Males were 1.30 times more likely to have had an injury compared to females. The odds of injury for children in the ‘‘others’’ race category (non-white) was 12% less than the odds in white children. There was no statistically significant association between risk of injury and a child’s age, the number of children in the household, or household poverty. The adjusted odds ratios, shown in Table 3, indicated that factors such as child sex, child age, number of children in the household, child race, and family poverty level cannot explain the increased risk of injury in children with autism, ADD/ADHD, learning disability, psychopathology, or other medical conditions. Children with autism, ADD/ADHD, or psychopathology were twice as likely to have had an injury as the unaffected controls, after controlling for these confounding variables. The adjusted ORs for the autism, ADD/ADHD, and psychopathology groups were 2.15 (95% CI: 1.00–4.60), 2.74 (95% CI: 1.63–4.59), and 2.06 (95% CI: 1.24–3.42), respectively. Although the adjusted OR in children with other medical conditions also reached statistical significance, 95% CI: 1.00–1.58, the magnitude of the OR (1.26) was not as great as those for the autism, ADD/ADHD, or psychopathology groups.
Table 1 Un-weighted and weighted 12-month prevalence of injury by study groups
Autism ADD/ADHD Learning disability Psychopathology Other medical conditions Unaffected controls
Un-weighted (%)
Weighted (%)
20.7 23.0 16.6 23.3 17.0 12.2
24.2 26.5 9.3 20.5 14.6 11.9
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Table 2 Unadjusted associations between children with disabilities or medical conditions and risk of injury Injury—un-weighted
Injury—weighted
Yes, n (%)
No, n (%)
Yes (%)
No (%)
OR
95% CI
Study group Autism ADD/ADHD Learning disability Psychopathology Other medical conditions Typical controls
17 44 51 49 307 1633
65 147 256 161 1494 11762
(0.5) (1.1) (1.8) (1.2) (10.8) (84.7)
0.8 2.5 1.5 2.3 13.7 79.2
0.3 1.0 2.1 1.3 11.5 83.8
2.36 2.66 0.75 1.91 1.26 1.00
1.11, 1.60, 0.49, 1.16, 1.02, Ref
Child’s sex Male Female
1216 (56.2) 947 (43.8)
7126 (50.2) 7056 (49.8)
57.5 42.5
51.1 48.9
1.30 1.00
1.11, 1.51 Ref
Child’s age (years) 3 4 5
788 (36.4) 738 (34.1) 638 (29.5)
4902 (34.5) 4693 (33.1) 4595 (32.4)
34.4 34.4 31.2
33.1 34.4 32.5
1.08 1.04 1.00
0.90, 1.31 0.85, 1.28 Ref
# of children in the household 1 2 3+
731 (33.8) 902 (41.7) 531 (24.5)
4904 (34.6) 6048 (42.6) 3238 (22.8)
18.9 40.9 40.2
17.8 41.2 41.0
1.00 0.94 0.92
Ref 0.79, 1.10 0.76, 1.12
1667 (81.8) 370 (18.2)
10203 (78.4) 2818 (21.6)
78.4 21.6
74.0 26.0
1.00 0.78
Ref 0.62, 0.99
14.6 18.3 20.2 37.7 9.2
16.7 18.2 18.5 35.4 11.1
0.82 0.94 1.03 1.00 0.78
0.63, 0.75, 0.85, Ref 0.55,
Child race White Others Household’s poverty levela <100% 100–184% 185–299% 300% Missing
264 356 476 903 165
(0.8) (2.1) (2.4) (2.3) (14.6) (77.7)
(12.2) (16.5) (22.0) (41.7) (7.6)
1742 2333 3014 5769 1332
(12.3) (16.4) (21.2) (40.7) (9.4)
5.00 4.40 1.16 3.14 1.56
1.05 1.20 1.23 1.10
a
The percentage of poverty level was derived by comparing the income-to-household-size measure against DHHS Federal Poverty Guidelines. A detailed description of the development of this poverty indicator is available in Blumberg et al. (2005).
Table 3 Adjusted associations between children with disabilities or medical conditions and risk of injury
Autism ADD/ADHD Learning disability Psychopathology Other medical conditions Unaffected controls
ORadj
95% CI
2.15 2.74 0.78 2.06 1.26 1.00
1.00, 1.63, 0.50, 1.24, 1.00, Ref
4.60 4.59 1.22 3.42 1.58
Note: Multivariate regression model adjusted for child sex, child age, number of children in the household, child race, and family poverty level.
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3. Discussion Findings from this study indicated that children with autism, ADD/ADHD, and other psychopathology were about two to three times more likely to experience an injury or accident that needs medical attention compared to unaffected controls. Consistent with results from Sherrard, Tonge, and Ozanne-Smith (2002), where the study sample had a wider age range (5–29 years), we found that social and family factors had minimal effect on the risk of injury. Based on previous literature, it is not surprising that the ADD/ADHD group appeared to have the highest risk of injury among the case groups (i.e., autism, ADD/ADHD, learning disability, psychopathology, and other medical conditions) and the control group (Pastor & Reuben, 2006; Swensen et al., 2004; Xiang et al., 2005). The finding that children with autism are at higher risk for injury supports the previously described hypothesis and is an association that has not been examined in a comparative study prior to this report. Whether the increased risk in children with autism is due to sensorimotor deficits or behavioral abnormalities, including hyperactivity, social avoidance, and poor judgment remains a question. These findings need to be considered within the context of the parent-reported data, and the cross-sectional study design. The fact that diagnoses of the children (e.g. autism, ADD/ADHD, learning disability, etc.) were obtained from parent report and were not validated by clinicians is the main limitation of our study. Because of this, there could be some misreporting of diagnoses. In addition, the injury questions included in NSCH did not specify whether they were intentional, unintentional, or disease/medical condition related, and we were unable to determine whether the increased risk was due to environmental factors (e.g. inadequate safety in the home or childcare setting, lack of parental supervision), symptoms of comorbid conditions (e.g. seizures), or associated behaviors (e.g. self-injury). Information bias is also possible if parents of children with developmental disabilities or medical conditions systematically reported injuries differently than parents of typically developing children. Furthermore, parents of children with developmental disabilities or medical conditions may be more likely to request medical attention when an injury happens to their child. For example, parents of children who are hyperactive, such as those with the diagnoses of ADD/ADHD or autism, may be more vigilant than parents of typically developing children. Through experiences with previous injuries these parents may tend to request medical attention more quickly or more often than other parents. Another example is that many children with autism do not respond to pain in a typical manner. Parents of those children may also be more apt to seek medical attention, knowing this characteristic of their child. Nevertheless, this study utilized data from a nationally representative sample with large numbers in the study groups, especially the case groups, which provides sufficient statistical power to examine injury in children with developmental disabilities and medical conditions during early childhood. The implications from this study are that parents, caretakers, and educational personnel involved with young children with autism, ADD/ADHD, or other psychopathology should receive additional education on injury and accident prevention. Injury prevention needs to be emphasized in order to reduce the excess incidence of injury in children with developmental disabilities and medical conditions. In addition, both general pediatricians and specialists (e.g., pediatric neurologists, psychiatrists, and psychologists) should be aware of the increased potential for injury in children with autism, ADD/ADHD or other psychopathology, in order to contribute to the education and awareness of parents, caretakers, and school personnel. Although parents or caregivers of children with developmental disabilities might be aware of the greater risk documented in this study, it may be difficult for them to quickly detect the severity of an
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injury in children whose disability is accompanied by a decreased ability to communicate and socially interact. Heightened awareness, detailed histories, and a lower threshold at which to conduct a thorough exam and/or imaging and laboratory testing may be necessary in this situation. In order to determine the prevention efforts that would be most effective, future studies need to clarify the extent to which injuries in young children with autism, ADD/ADHD, and psychopathology are related to (1) core symptoms and/or comorbid conditions (e.g., seizures or sensorimotor deficits), (2) associated behaviors (e.g., self injury), or (3) unintentional injuries due to factors such as lack of sufficient attention from caregivers. Acknowledgment Li-Ching Lee’s and Rebecca A. Harrington’s effort was supported by CDC cooperative agreement U10/CCU320408-05. A preliminary version of this paper was presented in part at the Second North American Congress of Epidemiology, Seattle, Washington, US, June 21–24, 2006. The analyses, interpretations, and conclusion addressed in this publication are the authors’ responsibility and are not a representation of the National Center for Health Statistics’ opinion. References Bennett Murphy, L. M. (2001). Adolescent mothers’ beliefs about parenting and injury prevention: Results of a focus group. Journal of Pediatric Health Care, 15, 194–199. Blumberg, S., Olson, L., Frankel, M., Osborn, L., Srinath, K., & Giambo, P. (2005). Design and operation of the national survey of children’s health, 2003. National Center for Health Statistics: Vital and Health Statistics 1. Canitano, R. (2007). Epilepsy in autism spectrum disorders. European Child & Adolescent Psychiatry, 16, 161–166. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. (2005). Web-based injury statistics query and reporting system (WISQARS). Retrieved November 15, 2006, from www.cdc.gov/ncipc/wisqars Danielsson, S., Gillberg, I. C., Billstedt, E., Gillberg, C., & Olsson, I. (2005). Epilepsy in young adults with autism: A prospective population-based follow-up study of 120 individuals diagnosed in childhood. Epilepsia, 46, 918–923. Gurney, J. G., McPheeters, M. L., & Davis, M. M. (2006). Parental report of health conditions and health care use among children with and without autism: National survey of children’s health. Archives of Pediatrics & Adolescent Medicine, 160, 825–830. Leland, N. L., Garrard, J., & Smith, D. K. (1994). Comparison of injuries to children with and without disabilities in a daycare center. Journal of Developmental and Behavioral Pediatrics, 15, 402–408. Leyfer, O. T., Folstein, S. E., Bacalman, S., Davis, N. O., Dinh, E., Morgan, J., et al. (2006). Comorbid psychiatric disorders in children with autism: Interview development and rates of disorders. Journal of Autism and Developmental Disorders, 36, 849–861. Limbos, M. A., Ramirez, M., Park, L. S., Peek-Asa, C., & Kraus, J. F. (2004). Injuries to the head among children enrolled in special education. Archives of Pediatrics & Adolescent Medicine, 158, 1057–1061. Matson, J. L., & Nebel-Schwalm, M. S. (2007). Comorbid psychopathology with autism spectrum disorder in children: An overview. Research in Developmental Disabilities, 28, 341–352. McCaig, L. F., & Nawar, E. N. (2006). National hospital ambulatory medical care survey: 2004 emergency department summary. Advance data from vital and health statistics; no 372, Hyattsville, MD: National Center for Health Statistics. Pastor, P. N., & Reuben, C. A. (2006). Identified attention-deficit/hyperactivity disorder and medically attended, nonfatal injuries: US school-age children, 1997–2002. Ambulatory Pediatrics, 6, 38–44. Ramirez, M., Peek-Asa, C., & Kraus, J. F. (2004). Disability and risk of school related injury. Injury Prevention, 10, 21–26. Rinehart, N. J., Tonge, B. J., Bradshaw, J. L., Iansek, R., Enticott, P. G., & McGinley, J. (2006). Gait function in highfunctioning autism and asperger’s disorder: Evidence for basal-ganglia and cerebellar involvement? European Child & Adolescent Psychiatry, 15, 256–264. Rowe, R., Maughan, B., & Goodman, R. (2004). Childhood psychiatric disorder and unintentional injury: Findings from a national cohort study. Journal of Pediatric Psychology, 29, 119–130. Scheidt, P. C., Harel, Y., Trumble, A. C., Jones, D. H., Overpeck, M. D., & Bijur, P. E. (1995). The epidemiology of nonfatal injuries among US children and youth. American Journal of Public Health, 85, 932–938.
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