Hamid Soori  ( Safety Promotion & Injury Prevention Research Center, School of Public Health Shahid Beheshti University of Medical Sciences- Tehran, Iran )
Kambiz Abachizadeh  ( Resident of Community Medicine Shahid Beheshti University of Medical Sciences- Tehran, Iran )

Objective: To examine the association between health-related quality of life (HRQOL) and unintentional injuries among children.
Methods: Overall, 3375 children aged 6-10 years were randomly selected from primary schools in Iran. HRQOL was measured by 56 items taken from seven domains of TNO AZL child quality of life (TACQOL) parent form. Parents were interviewed to collect information about incidence, cause and a brief description of injury within the past 12 months prior to the study.
Results: The response rate was 3375 of 3792 (89%). There was a significant trend for increasing occurrence of injury with decreasing of HRQOL (P<0.001). Adjusted OR for injury was significantly higher in very low (2.38, 95% CI: 1.45-3.86), low (2.18, 95% CI: 1.34-3.56), medium (1.73, 95%CI: 1.06-2.83) HRQOL groups compared to reference group (very high HRQOL). The median of total HRQOL (P<0.001) and all its domains (P=0.017) (except autonomous functioning) was less in injured group compared to the uninjured one.
Conclusion: This study found an association between HRQOL and unintentional injury among primary schoolchildren. This is a preliminary finding and so further investigations with a well-defined analytical design needs to be done (JPMA 58:674; 2008).

Unintentional injury is a leading threat to children's health.^1-3 It is estimated that in some European countries one in four children receive medical attention for an injury each year, in either primary or secondary care.⁴ The high proportion of children and young adults and the substantial socio-economic consequences of childhood injuries in less developed countries require prudent attention to the issue of injury control.⁵ The identification of the characteristics that contribute to injury risk is critical to the development and evaluation of paediatric injury prevention strategies.⁶
Injuries result from a predictable interaction among host, environment, and injury agents.⁶ The significant association of child behavioural characteristics with injury risk supports recommendations by previous researchers that child behavioural characteristics be considered as a potential predictor in childhood injury research.^7-9 There is increasing evidence that children differentially engage in risk behaviours based on individual-difference characteristics (e.g., behavioural intensity and inhibitory control).¹⁰
Health-related quality of life (HRQOL) has become recognized as an important health outcome, some contend the most important outcome in child health services research.^11,12 No other study, to our knowledge, has documented association between HRQOL as a personal factor and probability of occurring risk taking behaviour or unintentional injury. However, there are some studies about association between unintentional injury and risk factors related to some domains of HRQOL. For example, the association of self-reported poor health status, poorer ability to concentrate and emotion-based factors with injuries has been investigated.^13,14 Risk taking has been related to aspects of temperament, aggressive behaviour, perceptual analysis skills, beliefs about injury vulnerability and estimation of physical abilities.¹⁵ These risk factors might be used as proxies for HRQOL domains. So, domains of HRQOL and consequently total HRQOL might be associated with occurrence of unintentional injury.
The mechanism of effect of HRQOL on unintentional injury is ambiguous in spite of some associations between domains of HRQOL and occurrence of injury. The relationship between HRQOL and risk taking behaviour or human errors might be other mechanisms of attaining injury.
The aim of this study was to test whether HRQOL was associated with unintentional injuries among children aged 6-10 years.

From a total of 400 primary schools in Iran, with 128,499 pupils, 76 schools were randomly selected in five different educational districts according to the number of students. Schools were stratified by number of pupils in each one, and by private/state type. From each school 50 pupils (10 pupils in each classroom of year classes one to five) aged 6 to 10 years, were randomly selected. Parents (mothers) of selected pupils were invited to their children's schools on different occasions by an invitation letter. The mothers completed and signed an informed consent form to collect information from them and their children by interviewers. Children living without either mother or both parents were excluded. For each school two trained interviewers completed the questionnaires. There were questions for measuring HRQOL and about demographic characteristics of children, occurrence of unintentional injury, family status and parent's job and education.
For measuring HRQOL 56 items taken from seven domains of TNO AZL child quality of life (TACQOL) parent form were employed.¹⁶ The questionnaire was in English and translated into the Persian language. Seven 8-item scales were physical, motor, autonomous, cognitive and social functioning, positive and negative emotions. In each item, the frequency of occurrence of domains was assessed. All domains were computed by totaling "always," "often," "only within the past few weeks," "occasionally," and "never." Items were scored by assigning a value of 5 for "always" to 1 for "never" for positive well-being items (e.g., social functioning) ,and 5 for "never" to 1 for "always" for negative well-being items (e.g., negative emotions). Total scales of HRQOL scored from 56 to 280 (8-40 for each domain), with higher score indicating better HRQOL. The reason for this type of categorization was clarifying association between HRQOL and unintentional injury and probability of calculating odds ratio. More details about the measuring of children's HRQOL are available elsewhere.¹⁷
Information on children's unintentional injuries within the past 12 months prior to the date of study was collected from parents. There were questions on occurrence, cause and a brief description about the injury. We defined that an injury event, to be counted, must have caused the person to go to a hospital or clinic, resulting in medical attendance, so only moderate to severe injuries were included while 'mild to some moderate injuries' were excluded. Data of unintentional injury reported by parents were confirmed by 17 accident and emergency departments in the city. The definition of unintentional injury used in this study followed the International Classification of Diseases-version 10 (S00-T98 and V01-Y98).¹⁸
Statistical package for social sciences (SPSS-version 11.5) was employed for all data analyses. Mann-Whitney test was used to compare HRQOL and its seven domains in injured and uninjured children because the data of HRQOL were severely left skewed. There was not any standard base for categorization of HRQOL in literature review. Scale reliability for Persian questionnaire was assessed by Cronbach alpha.
The association between HRQOL and occurrence of unintentional injury was assessed using binary logistic regression. Child's sex and age, birth order, number of children in family and mother's education level were supposed as probable confounding variables. The association between occurrence of injury and these variables were explored by univariate analysis. Only significant variables were controlled to assess the association of each level of HRQOL and injury events. Results are presented as cross-tabulations, unadjusted and adjusted odds ratio (OR) with 95% confidence interval (CI). Chi square trend test (linear by linear association) was employed if there was a trend for children with lower HRQOL to have a higher incidence of injury. There was little missing data in this study which did not have any effect on the results.

Children were categorized into five ordered groups as quintiles for amount of HRQOL: 56-225 (very low), 226-245 (low), 246-259 (medium), 260-269 (high), 270-280 (very high). The Cronbach alpha was 0.74, 0.75, 0.73, 0.81, 0.89, 0.73, 0.90 and 0.77 for total HRQOL, body, motor, cognitive, autonomous, social functioning and positive and negative moods, respectively.
The response rate was 3375 of 3792 (89%). The mean age of mothers and their children were 34.9±6.4 years, and 7.9±1.5 years, respectively. Overall, 3264 (96.7%) children were living with both parents, and 49.3% were males.[(t1)] [(t2)] 
Of all the parents who participated in the study, 210 reported their children's injury event within the past 12 months prior to the date of study. The incidence rate (I.R) of unintentional injury was 6.2% (95%CI: 5.5-7.1%, n=3375). The top five causes of unintentional injuries were from falls (51.6%, I.R= 3.2%, n=108), transport accidents (25.1%, I.R=1.6%, n=53), struck by thrown, projected or falling object (11.2%, I.R=0.7%, n=24), poisoning (5.1%, I.R=,0.33%, n=11) and burns and scalds (4.7%, I.R=0.3% , n=10).
Total scales were scored from 56 to 280 (8-40 for each domain), with higher score indicating better HRQOL. The incidence rates of unintentional injury were 8.3%, 7.9%, 6.3%, 5.0% and 3.7% for very low, low, medium, high and very high groups of HRQOL, respectively. The linear-by-linear association indicated that there was a significant trend for increasing occurrence of injury with decreasing of HRQOL (P<0.001). [(t3)]
The incidence rate of unintentional injury in boys was more compared to girls (8.1% versus 4.4%, P<0.001). Children's mean age, mother's educational level, child's birth order and number of children in family were not significantly different between injured and uninjured groups. (Table 1). Unadjusted OR of injury event and adjusted OR by sex were calculated for each level of HRQOL. OR was significantly higher in very low, low, medium HRQOL groups compared to reference group (very high HRQOL). There was no significant difference between very high and high HRQOL groups (Table 2).
HRQOL and its seven domains were compared among injured and uninjured groups. The median of HRQOL was less in injured group compared to uninjured ones (P<0.001). All domains of HRQOL were significantly less in injured groups except for domain of autonomous functioning (Table 3).

This is the first study, to our knowledge, aimed to assess association between HRQOL and occurrence of unintentional injury in this group of children. The results suggest that level of HRQOL and its domains (except autonomous functioning) for injured children are significantly less compared to uninjured group. Also, there was a trend for children with lower HRQOL to have a higher incidence of unintentional injury. Similar to other studies,^13,14,19-21 males had higher injury rates than females and the most frequent cause of injury was a fall.
The high response rate (89%) gives credibility to the results of our study. It was a population-based study and the subjects should be a good representation of the children in the city.
There are few similar studies in literature to be employed for comparing our findings with students in primary schools in this community. Some risk factors of unintentional injury related to domains of HRQOL have been assessed in different studies. For example, self-reported poor health status reported as a risk factor in school children, is related to body functioning domain of HRQOL.¹³
Findings show that cognitive factors predict childhood injury.^1,7 Cognitive factors influence children's decisions about engaging in behaviours that threaten their safety.¹ The judgment of risk is related to self-reported risk taking behaviour.^19,22 Children who underestimate the environmental risk or overestimate their physical activity have a higher rate of unintentional injury.^19,20,22 Also, difficulty in concentration or easy diversion of attention increases the risk of injury.¹³ These risk factors might be related to cognitive functioning domain of HRQOL.
There are some probable risk factors related to positive and negative emotions and social functioning domains of HRQOL. For example, temperament is associated with child unintentional injury risk.^15,19,20 In addition, aggressiveness, oppositional, impulsive and under-controlled behaviour predict an increase risk of subsequent and concurrent injury event.^7,15,19,22 Antisocial behaviours, discipline problems and disruptive behaviours are other risk factors of injury.^7,10,23
Few published studies have carefully considered how individual differences in motor ability may lead some children to have increased risk of injury. Available literature examining children's motor ability and possible links to unintentional injury risk is mixed.²⁴ Autonomous functioning was not different between injured and uninjured children in our study. There was no other study for comparison.
The inherent weakness of cross-sectional studies is applicable to our results. The time of measuring HRQOL and occurring unintentional injury are almost the same although measuring HRQOL at the point of time may determine quality of life in previous time. For this reason, association identified between HRQOL and unintentional injury did not necessarily imply causal relationship and more studies are necessary to document causality relationship.
In this study, the translated questionnaire to Persian language was validated; but, cultural differences with other places in Iran and other countries decrease the generalizability of this study.
In this study, some probable confounders were controlled; but, it was necessary to control more exact variables about parent's surveillance, environmental agents and socioeconomic status as confounders to document effect association between HRQOL and injury event. It was impossible in this study, because it was secondary analyses of data. Some significant results might be due to large sample size; e.g., significant difference of motor functioning between injured and uninjured children.
In this study, maybe some parents could not remember the occurrence of injuries amongst their children or attendance at the hospitals/clinics because of injuries over the year prior to the data collection, which might lead to underestimations of the injury rates.
In this study, children's HRQOL was measured with TACQOL, a developed generic instrument.²⁴ However, it is noted that each research who purports to address the quality of life actually examines a very narrow and specific set of factors.^17,25
The best way to decrease incidence of unintentional injury is prevention.^13,19,20 Injury scholars have long debated the relative value of environmentally oriented injury prevention strategies versus person-oriented.²⁰ This study suggests that preventive strategies, while addressing broader community and environmental risk factors for injuries, need to address the human factors such as quality of life associated with these injuries. Also, it improves the concept of HRQOL application as a predictor. HRQOL is usually used as outcome in research, seldom used as a predictor.^11,12
In conclusion, this study found an association between HRQOL and unintentional injury. This is a preliminary finding and further investigations with a well-defined analytical design need to be done. If the role of HRQOL as a predictor of unintentional injury is demonstrated by complementary studies, it can be considered in preventive strategies and proper interventions can be designed for control of injury. Children's HRQOL should be applied as a predictor factor for their unintentional injuries and need to be considered on prevention and control of childhood injury programs.

The authors would thank Dr. Alireza Abadi, for statistical advice, parents and children who participated in this study and the staff of selected primary schools for their assistance.

1. Morrongiello BA, Matheis S. Determinants of children's risk-taking in different social-situational contexts: The role of cognitions and emotions in predicting children's decisions. J Appl Dev Psychol. 2004; 25: 303-26.                                          
2. Reading R, Langford IH, Haynes R, Lovett A. Accidents to preschool children: comparing family and neighborhood risk factors. Soc Sci Med 1999; 48:321-30.
3. Lalloo R,  Sheiham A. Risk factors for childhood major and minor head and other injuries in a nationally representative sample. Injury 2003; 34:261-6.
4. Otter H, Schellevis FG, Damen J, Vander-Wouden JC, Van Suijlekom-Smit LW, Koes BW. Epidemiology of unintentional injuries in childhood: a population-based survey in general practice. Br J Gen Pract 2005; 55:630-3.
5. Roudsari BS, Shadman M, Ghodsi M. Childhood trauma fatality and resource allocation in injury control programs in a developing country. BMC Public Health 2006; 6:117.
6. Garzon DL. Contributing factors to preschool unintentional injury. J Pediatr Nurs 2005; 20:441-7.
7. Dal Santo JA, Goodman RM, Glik D, Jackson K. Childhood unintentional injuries: factors predicting injury risk among preschoolers. J Pediatr Psychol 2004; 29:273-83.
8. Lund J, Aaro LE. Accident prévention. Presentation of a model placing emphasis on human, structural and cultural factors. Safety Science 2004; 42:271-324.
9. Turner C, McClure R, Pirozzo S. Injury and risk-taking behavior- a systematic review. Accid Anal Prev 2004; 36:93-101.
10. Morrongiello BA, Walpole B, Lasenby J. Understanding children's injury-risk behaviors: wearing safety gear can lead to increased risk taking. Accid Anal Prev 2007; 39:618-23.
11. Seid M, Varni JW, Segall D, Kurtin PS. Health-related quality of life as a predictor of pediatric healthcare costs: a two-way prospective cohort analysis. Health Qual Life Outcomes 2004; 2:48.
12. O'Conner R. Measuring quality of life in health. London: Churchill Livingstone. 2004 pp 264.
13. Sun YH, Yu IT, Wong TW, Zhang Y, Fan YP, Guo SQ. Unintentional injuries at school in China - patterns and risk factors. Accid Anal Prev 2006; 38:208-14.
14. Field CA, O'Keefe G. Behavioral and psychological risk factors for traumatic injury. J Emerg Med 2004; 26:27-35.
15. Morongiello BA, Lasenby J. Finding the daredevils: development of a Sensation Seeking Scale for children that is relevant to physical risk taking. Accid Anal Prev 2006; 38:1101-6.
16. Vogels AG, Verrips GH, Verloove-Vanhorick SP, Fekkes M, Kamphuis RP, Koopman HM, et al. Measuring health-related quality of life in children: the development of the TACQOL parent form. Qual Life Res 1998; 7:457-65.
17. Soori H.. Measuring health-related quality of life among primary school children in Ahwaz, Iran. J Prim Prev. 2004; 25:125-32.
18. World Health Organization. International Statistical Classification of Diseases and Related Health Problems. Geneva: World Health Organization; 1992.
19. Schwebel D, Barton BK. Contributions of multiple risk factors to child injury. J Pediatr Psychol 2005; 30:553-61.
20. Schwebel D, Bounds ML. The role of parents and temperament on children's estimation of physical ability: links to unintentional injury prevention. J Pediatr Psychol 2003; 28:505-16.
21. Soori H, Naghavi M. Childhood deaths from unintentional injuries in rural areas of Iran. Inj Prev 1998; 4:222-4.
22. Soori H, Bhopal RS. Parental permission for children's independent outdoor activities: Implications for injury prevention. Eur J Public Health 2002; 12:104-9.
23. Koven R, McColl MA, Ellis P, Pickett W. Multiple risk behaviour and its association with head and neck injuries: a national analysis of young Canadians. Prev Med 2005; 41:240-6.
24. Schwebel DC, Binder SC, Sales JM, Plumert JM. Is there a link between children's motor abilities and unintentional injuries? J Safety Res 2003; 34:135-41.
25. Verrips GH, Vogels GC, Koopman MK, Theunissen CM, Kamphuis P, Fekkes M. Measuring health-related quality of life in a child population. Eur J Public Health. 1999; 9:188-93.