injuries could impose adverse mental and physical effects ; albeit , these taints are affected with economic and cultural status of the family .
the prevalence of injuries is affected by different factors as the place of injury occurrence .
for instance , most of the injuries occur at homes and schools , they mainly comprise of falling , bone fractures , head trauma , burns , cuts , as well as vehicle accidents out of home and schools .
different epidemiological studies have reported the prevalence of injuries in iranian children ; however , most of these studies comprised small sample size and have been conducted in restricted areas or reported hospital - based information .
this study aims to assess the frequency , causes , and places of injury occurrence in a nationally representative sample of iranian children and adolescents , as well as on places allocated for referring the injured individuals .
this nationwide study was conducted in 2011 - 2012 as the fourth national survey of a school - based surveillance program entitled the childhood and adolescence surveillance and prevention of adult noncommunicable disease study .
we have previously reported the methodology of this study , and here we explain the methods related to the current paper .
the study population consisted of elementary , middle- , and high - school students from rural and urban areas of iran .
they were selected by multistage , cluster sampling method from 30 provinces of the country ( 48 cluster of 10 students in each province ) .
stratification was performed in each province according to location of residence ( urban , rural ) , and school grade ( elementary , middle- and high - school ) proportional to the size and with equal sex ratio ; that is , in each province , the number of boys and girls were the same and the ratios in urban and rural areas were proportionate to the population of students in each area . in this way , the number of samples in rural , urban areas and in each school grade was divided proportionally to the population of students in each grade .
cluster sampling with equal clusters was used in each province to reach the sample size of interest .
the clusters were determined at the level of schools , containing 10 samples in each cluster .
the sample size was determined according to the cluster sampling method ; the maximum sample size that could give a good estimate of all risk factors of interest was selected .
therefore , the sample size was calculated as 480 subjects in each province , therefore , 48 clusters of 10 subjects were selected in each province .
the questionnaire of the world health organization - global school - based student health survey was used .
continuous variables are presented as mean ( standard deviation ) and categorical data as number ( % ) .
categorical data were analyzed by chi - square test . the sampling method ( cluster sampling )
the study population consisted of elementary , middle- , and high - school students from rural and urban areas of iran .
they were selected by multistage , cluster sampling method from 30 provinces of the country ( 48 cluster of 10 students in each province ) .
stratification was performed in each province according to location of residence ( urban , rural ) , and school grade ( elementary , middle- and high - school ) proportional to the size and with equal sex ratio ; that is , in each province , the number of boys and girls were the same and the ratios in urban and rural areas were proportionate to the population of students in each area . in this way
, the number of samples in rural , urban areas and in each school grade was divided proportionally to the population of students in each grade .
cluster sampling with equal clusters was used in each province to reach the sample size of interest .
the clusters were determined at the level of schools , containing 10 samples in each cluster .
the sample size was determined according to the cluster sampling method ; the maximum sample size that could give a good estimate of all risk factors of interest was selected .
therefore , the sample size was calculated as 480 subjects in each province , therefore , 48 clusters of 10 subjects were selected in each province .
the questionnaire of the world health organization - global school - based student health survey was used .
continuous variables are presented as mean ( standard deviation ) and categorical data as number ( % ) .
categorical data were analyzed by chi - square test . the sampling method ( cluster sampling )
this survey comprised 13486 students ( 90.6% participation rate ) consisting of 49.2% girls and 50.8% boys .
the average age of participants was 12.47  3.36 years , without significant difference in boys ( 12.36  3.40 years ) and girls ( 12.58  3.32 years ) respectively .
overall , 75.6% of students were from urban and 24.4% were from rural areas ; 46% of students were from elementary schools , 25.9% from middle - school , and 28.1% from high - school . according to age categories 32.26% , 34.70% , and 33.04% were in the age groups of 6 - 10 years , 11 - 14 years , and 15 - 18 years , respectively .
characteristics * of study participants according to gender , living area , and educational level : the caspian - iv study the frequency of one injury in the last 12 months was 13.93% , the prevalence of two , three , and at least four injuries were 3.35% , 1.56% , and 1% .
42% respectively ; thus , 20.25% ( n = 2645 ) of children and adolescents reported having been injured minimally once in the previous 12 months [ table 2 ] .
this frequency was significantly higher in boys than in girls ( 25.74% vs. 14.58% , respectively , p < 0.001 ) .
this frequency was not significantly different in urban ( 20.11% ) and rural areas ( 20.69% ) .
the corresponding figures were 19.43% , 23.14% and 18.94% in elementary , middle , and high - school students respectively ( p > 0.05 ) .
frequency of injuries during 12 months prior to the study according to gender , living area and educational level : the caspian - iv study most of the children and adolescents ( 39.92% ) were injured at their home or house yard ; mean while this frequency was 22.50% in schools , and 17.09% in street [ table 3 ] .
the frequency of injuries either in homes or schools was significantly higher in boys ( 35.17% and 22.12% ) than in girls ( 48.61% and 23.18% ) , respectively , p < 0.001 [ table 3 ] .
the frequency of injuries occurred in either homes or schools was higher in rural ( 40.87% and 27.30% ) than in urban areas ( 39.61% and 20.89% ) respectively , p < 0.001 .
place of injury occurrence during 12 months prior to the study according to gender , living area , and educational level : the caspian - iv study the frequency of injuries occurred at homes of students of elementary , secondary and high - schools was 42.77% , 38.56% , 36.77% respectively which was statistically significant ( p < 0.001 ) .
furthermore , the prevalence of injuries occurred at schools in elementary was significantly higher than secondary and high - schools ( 24.94% , 24.02% and , 16.74% respectively ) ( p < 0.001 ) .
moreover , 18.88% of injured students in high - schools were injured in streets or routes in the previous 12 months .
table 4 shows the place for injuries treatment . as it shows 32.31% of the children and adolescents
were referred to the emergency department , this frequency was not statistically different between boys and girls ( 33.47% vs. 30.18% , respectively , p > 0.05 ) .
in addition , the frequency of referrals to physician 's office , clinics or public health centers , and school health services was 22.38% , 18.08% , and 7.81% , respectively .
the frequency of referrals to the emergency department of hospitals was higher in urban than in rural areas ( 35.02% vs. 24.80% , respectively , p < 0.01 ) , similarly , the frequency of referrals to clinics or public health centers was higher in urban than in rural areas ( 15.60% vs. 25.60% , respectively , p < 0.01 ) .
place of injury treatment during the 12 months prior to the study according to gender , living area and educational level : the caspian - iv study as shownin table 5 , 17.24% of participants reported that they have been injured while walking or running , 11.40% during biking , and 10.37% during motorcycle driving or road racing .
frequency of activity pattern in time of injury during 12 months prior to the study according to gender , living area and educational level : the caspian - iv study
the results of this nationwide study demonstrated that about 20% of iranian children and adolescents were minimally injured during 12 months before the current study . in addition , the frequency of injuries was higher in boys than in girls , but it had no significant difference in rural and urban areas .
some previous studies have documented that the frequency of injuries is relatively high in iranian children and adolescents , and usually boys are more injured than girls , similar to other studies .
this study showed that the most frequent places of injuries were homes , followed by schools .
the home injuries comprised falling , burning ( directly or indirectly ) and cut , whereas most of the school injuries occurred due to falling in playing fields .
therefore , more attention should be paid to the security issues of homes and schools to reduce injuries . in the current study , most school injuries occurred during the physical exercises , this is consistent with some previous studies ; therefore , physical activity consideration should be emphasized for injury prevention , as recommended before . in the current study ,
the most prevalent places for treatment of injuries both in urban and rural areas were emergency departments and health centers respectively ; this finding is consistent with some previous studies .
injuries are the leading cause of mortality in children and adolescents , and pose huge costs for the medical care and lost productivity .
most injuries had occurred at home ; therefore , it is necessary to increase the knowledge of families about safety issues for preventing home and recreation - related injuries .
it should be also ensured that all schools would have safe and healthy places for play and physical exercises of students .
training children and adolescents about safety and necessary precautions for preventing injuries can be effective in reducing injuries .
it seems that implementing a comprehensive and appropriate strategy comprising appropriately sport activities for every age group , determination and controlling the possible risks of sport activities , increasing medical facilities in play and sport grounds are crucial for injury prevention .
the cross - sectional nature of the study and using self - reported data are the main limitations of the current study . however , its nationwide coverage , and using a valid international questionnaire are its main strengths .
the cross - sectional nature of the study and using self - reported data are the main limitations of the current study
. however , its nationwide coverage , and using a valid international questionnaire are its main strengths .
preventing unintentional injuries should be considered as a health priority for iranian children and adolescents . the importance of safety at home and schools should be underscored .
 background : this study aims to assess the frequency , causes , and places of injuries in a nationally representative sample of iranian children and adolescents , as well as the referral , places allocated for injured individuals.methods:this nationwide study was conducted in 2011 - 2012 among 13486 elementary , secondary and high - school students who were selected by random cluster stratified multistage sampling from 30 provinces in iran . the global school - based health survey questionnaire of the world health organization was used.results:the study participants consisted of 50.8% boys , 75.6% urban resident with a mean age of 12.5 years . 
 overall , 20.25% of participants reported that they were minimally injured once in the last 12 months ; this prevalence was higher in boys than in girls ( 25.74% vs. 14.58% , respectively , p < 0.001 ) , without significant difference in urban ( 20.11% ) and rural ( 20.69% ) areas . 
 most of them ( 39.92% ) were injured at homes or house yards with higher prevalence in girls than in boys ( 48.61% vs. 35.17% , respectively , p < 0.001 ) and in rural than in urban areas ( 27.30% vs. 20.89% , respectively , p < 0.001 ) . 
 schools were reported as the second prevalent site of injury occurrence ( 22.50% ) . 
 emergency departments and physician offices were the most prevalent referral places for injured individuals ( 32.31% and 22.38% , respectively ) . 
 most of the school injuries occurred during play or sport activities ( 45.92%).conclusions : prevention of unintentional injuries should be considered as a health priority . 
 appropriate preventive strategies should be enhanced at homes and schools . 
INTRODUCTION
METHODS
Study population and sampling framework
Statistical analysis
RESULTS
DISCUSSION
Study limitations and strengths
CONCLUSIONS