Analysis of Characteristics and Risk Factors of Unintentional Injuries in Children With Cerebral Palsy

In recent years, the incidence of accidental injuries among disabled children increased, including children with cerebral palsy(CP). However, there are few reports on the characteristics and risk factors of unintentional injuries in children with cerebral palsy. Therefore, we collected 117 children with CP as the research objects, and analyzed the characteristics and inuencing factors of unintentional injuries of them to provide effective preventive measures and reduce the incidence of accidental injuries in children with CP. Results reveal that the incidence of once unintentional injuries in children with CP in the past 3 months was 32.47%, and the incidence of re-injury was 3.4%, which was lower than that of normal or disabled children. In addition, our research also found that the causes of unintentional injuries of children with CP were mainly fall. The injured parts were mainly lower limbs and head and neck. The injuries mainly occured indoors, and most unintentional injuries occurred during when resting, sleeping or relaxing. Multivariate logistic regression analysis of this study found that girls, low family income and less time with their parents were risk factors for unintentional injuries in children with CP.


Introduction
Unintentional injuries refer to human injuries caused by various accidents, which are purposeless and unconscious injuries, such as drowning, car accidents, animal bites, burns, scalds, falls, poisoning, and medical accidents. Unintentional injuries which not only seriously affect children physical and mental health, but also bring a series of economic and social problems to the family and society, have become one of the most important public health issues in the 21st century [1][2][3] . Injuries were the leading cause of death for children aged 1-17, which resulted in the deaths of approximately 65,000 children each year. In addition, monitoring data in China in 2014 showed that the death rate of children and adolescents aged 0-17 was 22.90 per 100,000. The main causes of death among Chinese children and adolescents are drowning and road tra c injuries [4] . In China, 8.77 out of 100,000 children died from drowning, of which 56.58% were from 1 to 14 years old [5] . Besides, more than 18,500 children under the age of 14 died in road tra c accidents, which was twice that of Europe and 2.6 times that of the United States [6] .
Disability is de ned as a decline in long-term social skills (such as going to school or entertainment) due to physical or mental reasons. It seriously affected children's growth and development, reduced their school, social and recreational abilities, and brought a huge economic burden to their families and society at the same time [7,8] . Cerebral Palsy (CP) is a group of persistent central movement and postural development disorders, and activity limitation syndromes. This syndrome is caused by non-progressive brain damage to the developing fetus or infants [9,10] . Children with CP have been treated for a long time, but the children and their families had low awareness of unintentional injuries. Presently, there have been studies on the characteristics and risk factors of accidental injuries of disabled and non-disabled children at home and abroad [6,11] . More and more studies have shown that children with disabilities were more likely to be dangerous than children without [12,13] . One foreign study has shown that children with CP had a higher risk of accidental injury compared with children without CP. In addition, girls with CP had the highest risk of hospital-treated injury [14] . However, the study only described the characteristics of accidental injuries in children with CP, never elaborate on the risk factors of accidental injuries in children with CP. Therefore, this study collected 117 children with CP who were admitted to the Hunan Children's Hospital from January 1, 2018 to March 1, 2019 as the research objects to provide a theoretical basis for the health decisions of disabled children.  A single factor analysis of family factors found that the incidence of unintentional injuries in girls with CP was signi cantly higher than that in boys, and the difference was statistically signi cant (2 = 6.105, P = 0.013);The father's education and family income were the risk factors for unintentional accidental injury in children with CP (P < 0.05). Children with CP who spend less than 2 hours with their parents had a signi cantly higher risk of unintentional injury than children with CP who spend more than 4 hours together (2 = 8.076, P = 0.018) ( Table 2). This study included whether there was a construction site near the residence; whether the residence was close to the road; whether the surrounding environment was steep; whether there was a lake, river or water ditch around; whether the elevator was used to go upstairs; whether there were reworks at home; whether used a stove for heating in winter; whether the heat source was in a place that is was easy for children to touch; whether the oor in the home was non-slip; whether the indoor light was bright; whether the medicines in the home can be easily obtained; whether the fruit knives, kitchen knives, scissors and other sharp objects in the home could be accessed by children; whether children like toys such as marbles; and whether window guards were installed in the home. The analysis of the impact of 15 environmental factors on the unintentional injury of children with CP found that the rate of unintentional injuries in children with CP in the steep surroundings of the house (13/27, 58.1%) was signi cantly higher than that in children with at surroundings (25/90, 27.8%), and other environmental factors had no effect on unintentional injuries of children with CP (P > 0.05) ( Table 3). A single factor analysis of family factors found that the incidence of unintentional injuries in children with CP in the past year was the highest at the age of 11-18 years (9/9), and the older the child, the higher the incidence of unintentional injuries in the past year (χ2 = 16.225, P < 0.001). In addition, children with CP whose family population was greater than or equal to 6 had the highest incidence of unintentional injuries(9/12 75.0% )(χ2 = 6.336,P = 0.042) .Furthermore, the incidence of unintentional injuries in children with CP who lived with their grandparents in the past year was higher than that of children who lived with their parents and one of their parents(χ2 = 6.159, P = 0.046) ( Table 4).

The impact of different environmental factors on unintentional injuries in children with CP in the past year
The proportion of children with CP (11/17,64.7%) who can easily access sharp tools such as fruit knives, kitchen knives, and scissors at home had a signi cantly higher proportion of unintentional injuries than children who could not access( 39/100, 39.0%)(χ2 = 3.9236,P = 0.048). Other environmental factors had no effect on unintentional injury of CP children (P > 0.05). (Table 5). The results of multivariate logistic regression analysis showed that: after controlling for sociodemographic factors and family environment, the risk of accidental injury among girls and children among children with CP was four times that of boys. The risk of accidental injury for children with CP with a family income of 1,000-3,000 was 32.726 times that of children with CP with a family income of more than 10,000 yuan. The risk of intentional injury in children with CP who spend 2-4 hours with their parents per day was 5.815 times that of children with parents who spend more than 4 hours per day (Table 6).  [15,16] . In this study, the incidence of once unintentional injuries in children with CP in the past 3 months was 32.47%, and the incidence of re-injury was 3.4%, which was lower than that of normal or disabled children. In addition, our research also found that the causes of unintentional injuries of children with CP were mainly fall. The injured parts were mainly lower limbs and head and neck. The injuries mainly occurred indoors, and most unintentional injuries occurred when resting, sleeping or relaxing.
Multivariate logistic regression analysis of this study found that girls, low family income and less time with their parents were risk factors for unintentional injuries in children with CP.
According to existing studies, the incidence of unintentional injuries among primary and middle school students in China reached up to 49.22%, the number of unintentional injuries per capita reached 1.8 times per year, and the incidence of re-injury was 20.90% [17] .The above data suggest that the incidence of unintentional injury in children with CP was signi cantly lower than that of normal children in our study.
The reason might be that children with CP who need special care for daily life spend most of their time in wheelchairs or beds. In addition, many previous studies have found that children with disabilities had a higher risk of accidental injury than disabled children. Zhu et al. [9] found that the incidence of unintentional injuries in children with disabilities was signi cantly higher than that of normal children (15.6% vs. 10.9%, P < 0.05). Furthermore, a Meta-analysis involving 15 research subjects found that the risk of unintentional injury in children with disabilities was 2.39 times that of healthy children [3] . Sherrard et al. [10] took the Australian mentally disabled group as the research object and found that the rate of hospitalization for unintentional injuries among people with intellectual disabilities was twice that of the general population. Peiris-John, R et al. [18] found that the risk of unintentional injury in children with disabilities was 1.53 times that of normal teenagers. The reason might be that children with different types and severity of disabilities had different risks of accidental injury [6,11] . Besides, studies had shown that disabled children with epilepsy, communication disorders and mental problems were at greater risk of injury [12,19] . However, Maattanen, L et al. [14] conducted a study on 445 children with CP in Finland and found that the risk of unintentional injury in children with CP was 1.2 times that of children without CP, which was contrary to the results of this study. Meanwhile, he study also found that if the children with CP had any comorbidities (such as epilepsy, mental retardation, language impairment, hearing and vision impairment, etc.) in addition to lifelong movement disorders, the probability to suffer unintentional injuries of them would increase by 0.54 times. However, this study did not distinguish children with CP with simple dyskinesia and children with CP with comorbidities, which led to a different result from Maattanen, L et al.
This study found that the injuring mechanism of children with CP were mainly fall injuries, and the injured parts were mainly the lower limbs and head and neck. Similarly, previous study have shown that children with CP have a higher risk of traumatic brain injury than children without CP [14] . In addition, Zhu HP et al. [11] found that both disabled and normal children were mainly injured in the head and neck, and the main cause of injuries in was falls. Besides, this study found that the injury sites of children with CP mainly occurred indoors, and most of the unintentional injuries occurred during rest, sleep or leisure, which was similar to Zhu HP's nding. To normal children, Ellsässer G [20] conducted an injury epidemiological analysis on children under 15 years of age in Delmenhorst, Germany, and found that children under 5 years of age were mainly injured at home and around the home, while accidents of children between 5 and 14 most often occurred in schools, homes, roads or streets. Therefore, this reminds us that when formulating strategies to prevent unintentional injuries, we should formulate the most effective measures to prevent accidental falls [21] . At the same time, we need improve the home and school environment to reduce the risk of unintentional injury to children with CP [22] .
This study found that girls with CP were more likely to suffer accidental injuries than boys. Similarly, Maattanen, L et al. [14] found that the risk of unintentional injury in girls with CP was 1.4 times that of girls without CP. However, some studies have shown that boys with CP suffer more dental injuries than girls [23,24] . Family status was one of the important factors affecting the incidence of children's accidental injuries. This study found that children with low-income had a signi cantly higher risk of accidental injuries than children with high-income. Similarly, a Canadian study showed that the risk of unintentional injury for children with poor family nancial status was 1.67 times that of children with good family nancial status [25] . Furthermore, Saunders et al. [26] conducted a survey of 999,951 people aged 0-24 who immigrated to Canada and found that the incidence of unintentional injuries among refugees was 1.20 times (95% CI: 1.40, 1.62) that among non-refugees. This may be related to the poor living environment which leads fewer protective factors and poor supervision and management from family members for the children with CP. In addition, this study found that children with CP who spend less time with their parents had a signi cantly higher risk of unintentional injuries than children with CP who spend a long time with their parents. Similar to this result, previous studies had shown that children living with grandparents were more prone to accidental injuries [27] . However, some studies had shown that the time spent with their parents and whether they live with their parents had no effect on the incidence of accidental injuries in children with CP [28,29] . Children with CP could not take care of themselves, and most of the time they need guardians or parents to help them complete their daily life. Therefore, when parents were busy with work or spend less time with children due to other reasons, children had to be looked after by nanny or elderly people, which leads to ineffective parental supervision of children, lack of care and safety education for children, and nally lead to a high incidence of accidental injuries [30,31] .
Family environment factors were important risk factors for unintentional injuries to children, especially young children. For example, steep roads around homes, slippery oors, use of open braziers or stoves, and storage of reworks and recrackers are common in Chinese families, especially rural families.
These factors had a great impact on the occurrence of child injuries. However, this study found that in addition to whether the road around the home was steep, the location of the fruit knife, scissors and other sharp tools at home has an impact on the unintentional injury of children with CP, other family environment factors has no effect. This might be related to the peculiarities of CP, because these children were lagging behind normal children in completing turning over, sitting alone, crawling, standing on hold, and vocalization, and even some children with high muscle tone had lost the ability to move. However, The multivariate logistic regression analysis of this study did not nd any risk factors for the family environment.
This study still had certain limitations. First of all, the children with CP included in this study were hospitalized in the rehabilitation department of our hospital. Relatively speaking, their condition might be more serious, so there was a certain selection deviation. Secondly, this study did not include normal children for case-control studies, and the conclusions obtained were compared with normal children reported in the literature. Its universality and generalization require further case-control studies. Finally, this study did not include the CP subtypes, and did not study the impact of CP complications on the incidence of accidental injuries in children with CP.
Objects And Methods

Ethics Statement
The study was approved by the Ethics Committee of Hunan Children's Hospital (IRB No: HCHLL-2018-64). Informed written consent was obtained from the parents or caretakers of each child included in this study. All data collection from participants was fully anonymous. All methods were carried out in accordance with relevant guidelines and regulations.

Research content
(1) sociodemographic characteristics: including the child's gender, diagnosis, date of birth, age of parents, education level, family population, number of children, living conditions, learning stage, family economic situation, child's personality, the hours the child spend with their parents etc.
(2) Living environment: outdoor environment:(Q1): whether there was a construction site near the residence, (Q2) whether it was close to a road, (Q3) whether the surrounding environment was steep, (Q4) whether there were lakes, rivers or ditches, (Q5) whether there were elevators, etc. Indoor environment: (Q1) Whether there were reworks and recrackers, (Q2) whether a brazier was used for heating,(Q3) whether the heat source in the home was in a place that children can easily touch, (Q4) whether the oor in the home was non-slip, (Q5) whether the indoor barrier was bright, (Q6) whether the windows were installed with guardrails, (Q7) whether the medicines were easily available, (Q8) whether the fruit knives, kitchen knives, scissors and other sharp tools in the home could be obtained by children.
(3) Characteristics of unintentional injuries : the time, location, cause, severity, treatment after the injury, the result of the injury, the type of injury, and the location of the injury.

Related de nitions
An injury case was de ned as an incident in a child with CP who had caused medical attention in the past 3 or 12 months. We investigated the number of injured children with CP and the injury characteristics of each child. We used the main cause of the injury incident to describe the external cause.

Quality control
To ensure the smooth development and the quality of the investigation, we conducted strict quality control on every link involved in the investigation process, including quality control in the design phase, the investigators, the implementation phase, and the data collation and analysis process .

Statistical methods
Statistical analysis: we used SPSS26.0, EXCEL2010 and other software to logically sorted, analyzed and plotted the data, used frequency (n) and percentage (%) to describe the data. After the data was entered into the software, the data was processed through counting and comparison, and the chi-square test of the R×C list or Fisher's exact probability method and Logistic regression were used for data analysis.
Firstly, we described the injury characteristics of children with CP, including injury time, cause, type, injured body part, injury location and activities at the time, etc. Secondly, we used the chi-square test to evaluate the in uence of the existence of social demographic variables and environmental variables on the risk of accidental injury in children with CP in the past three months and one year. Finally, logistic regression model was used to assess the injury risk for sampled children by sociodemographic characteristics and home environment factors in multivariate model. In all analyses, a difference of P < 0.05 from the signi cance test was considered statistically signi cant. Declarations