Representative and valid information at the population level is essential for health planning and priority setting for interventions to control diseases, and for population-based evaluation of health programs. ¹ National representative studies may help us to have a view on these health concerns at national and regional levels. There have been conducted many national health surveys worldwide to prepare reliable information for policy making. ¹,²,³,⁴,⁵,⁶,⁷,⁸,⁹

Although, there are some Iranian health surveys available, which most of these previous studies have been limited to one city and thus their results could not be generalizable to the whole country; ¹⁰,¹¹,¹² however, there are also some national studies which have been considered all Iranian provinces. ¹³,¹⁴,¹⁵ Some of these studies were only on adult people ¹⁶,¹⁷,¹⁸,¹⁹ or only on special disease such as childhood dental problems ²⁰ or overweight and obesity. ¹³,¹⁴,²¹ Moreover, developing countries including Iran are facing with epidemiologic transition in disease and nutritional patterns ²² which in turn would raise the necessity for conducting a representative and comprehensive national health survey. Since Iran is a big country, taking into account the great diversity in socioeconomic and demographic factors in different provinces, it is expected to observe a substantial inequality in disease and disorder distribution across Iranian provinces. The aim of this study is to assess the potential difference of national prevalence distribution of clinical disorders distribution among 6-year-old Iranian children before school entry across Iranian provinces using national health assessment survey.

The data were collected as a nationwide screening program in a cross-sectional study. This program is regularly performed by the Ministry of Health and Medical Education and the Ministry of Education and Training among all children entering elementary schools. All Iranian children entering elementary school were studied. As in Iran, elementary education is mandatory; thus, the study population comprised all children entering public and private elementary schools. During summer 2009 (for three months), in 823 centers and 712 cities and regions, 955388 Iranian children entering elementary schools have been assessed physically and mentally by 5582 skilled health care staff.

The assessment had two levels: introductory (screening) and diagnostic levels. In the first level, probable diseases and disorders have been screened (in 13 different aspects) and potential patients were sent to verify their possible problems in the second level. The diagnosed patients then were referred to specialists for further treatment and some advices were given to their parents. Ethical concerns have been considered by the aforementioned ministries. The national Data and Safety Monitoring Board closely supervised the quality control and quality assurance of each survey. At first, the data-checking process was conducted at the provinces every week and then at national level monthly. The analysis has been done after editing.

Training sessions were organized for health-care providers who measured children′s weight and height according to standard protocols by using calibrated instruments. Body mass index (BMI) was computed as weight in kilograms divided by the square of height in meters. In all surveys, the growth charts of the Centers for Disease Control and Prevention were used, ²³ which are in close agreement with Iranian charts. ¹⁴

Overall health assessment, impaired vision (negative, positive, no corporation and unknown), color blindness (negative, positive, unknown), hearing impaired (negative, positive, no corporation and unknown), speech problems (negative, positive and unknown), appearance situation (anemic, cyanosed and edema), skin and hair (scabies and scalp ringworm), glands (hyperthyroidism and enlarged lymph nodes), eye problems, ear problems, deviated nasal, abnormal mucosa, adenoid, abnormality in height to age ratio and BMI, decayed teeth, having disease with special need for surveillance, hypertension (systolic: <70 and 120+, and diastolic: <20 and 100+), spinal situation (spinal disorders, kyphosis, lordosis, scoliosis, walking abnormalities and flat feet), abdomen (abdominal mass, enlarged spleen, hepatomegaly and hernia), chest (cardiovascular, thorax and lung diseases), genitourinary (genital ambiguity, undescended testicles, hernia, hydrosol and renal diseases), neurologic problems and puberty (precocious and delayed) were the considered health problems which were taken into account by general practitioner.

The children with potential disorders have been referred to specialists. The specialists have taken into account overall assessment (healthy or ill), vision examination (no problem, no glasses needed for now, glasses needed, amblyopia, medication-surgery supervision, vision-aid instrument (sent to normal school), vision-aid instrument (sent to special school) and blind), hearing examination (no problem, duct collapse, medical treatment, ear wash, one-sided ear problem, problem in one or two frequency, problem in low frequency, hearing-aid instrument (sent to normal school), hearing-aid instrument (sent to special school) and deaf), having both vision and hearing problems (sent to normal or special schools), dermal problems (head lice and scalp ringworm), dental problems (decayed, missed and filled teeth and gingivitis), special diseases (diabetes mellitus, cardiovascular diseases, epilepsy, asthma, hemophilia and Thalassemia), positive family history (diabetes mellitus, hypertension, smoking, atherosclerosis, tuberculosis, asthma, hemophilia, Thalassemia, seizure disorder, mental disorders and others), positive personal history (diabetes mellitus, hypertension, atherosclerosis, tuberculosis, asthma, hemophilia, Thalassemia, seizure disorder, mental disorders and others), need for special surveillance (no, yes and unknown), medication use history (no, yes and unknown) and sensitivity history (no, yes and unknown).

The data were analyzed using the Statistical Package for Social Sciences (SPSS) software package version 18.0 (SPSS Inc., Chicago, IL, USA). The absolute and relative frequencies of variables were obtained and demonstrated in Table 1, Table 2, Table 3.{Table 1}{Table 2}{Table 3}

Main characteristics of national health assessment survey on Iranian 6-year old children before entering school in 2009 are shown in Table 1. The number of health employees who helped to conduct this survey was 5582 health works through Iran. Of 955388 Iranian children aged 6-year old, 463076 (48.5%) children were girls, 727309 (76.1%) lived in urban area, 233755 (24.5%) did not have health insurance, 237808 (28.6%) spoke two languages at home, 110234 (11.5%) did not complete their vaccination, 146790 (15.4%) children were referred to specialists and 0.5% had to go to special schools.

Table 2 demonstrates the main clinical symptoms of these children reported by general practitioners. Of these children, 809593 (84.7%) were healthy. In addition, 3.1, 1.2, 1.8 and 1.4% had impaired vision, color blindness, hearing impaired and speech problems, respectively. Abnormalities in height to age ratio and body mass index (BMI) have been observed in 10.0 and 10.9% of Iranian children entering primary school, respectively. Furthermore, decayed teeth, having disease with special surveillance need, problems in hair - skin - glands - and ear - nose - and throat (ENT), spinal disorders and hypertension were observed in 56.7, 0.7, 6.4, 0.8, and 0.6% of Iranian children in 2009. Moreover, appearance of 3.3% of children was anemic, while only less than 0.1% of these children were cyanosed or edema, respectively. Less than 0.1% of children has showed scabies and scalp ringworms. Hypothyroidism and enlarged lymph nodes were diagnosed in 0.3% of children. Eye, ear, deviated nasal, abnormal mucosa and adenoid were reported in 0.6, 0.6, 0.1, 0.1 and 1.0% of Iranian 6-year children. Hypertension was in 5613 (0.6%) of children, with 0.4, 0.1, 0.1 and 0.1% with systolic blood pressure less than 70 and above 120 mmHg, and diastolic blood pressure less than 20 and more than 100 mmHg, respectively. Spinal disorders were diagnosed in 8045 (0.8%) of children. Abdomen, chest, genitourinary and puberty disorders were reported in less than 1000 children.

Main clinical disorders found by specialists are presented in Table 3. Most of the children who have been sent to specialists were healthy. Many of the children needed glasses to have a better vision. There were also many hearing problems among these children. Some children had combination of visual and hearing problems. There was also head lice and scalp ringworm among Iranian 6-year-old children. Some special diseases such as diabetes mellitus, cardiovascular diseases have also been reported. For some of these diseases, there was a familial and/or personal history.

To the best of our knowledge, the present study is one of the first Iranian reports providing information on national prevalence of clinical disorders from the entire population of children at school entry. We confirmed substantial differences in the regional distribution of diseases and disorders across Iranian provinces. ²¹,²⁴,²⁵,²⁶,²⁷

Since various socioeconomic groups are living in different provinces and therefore the observed differences among provinces on children disorders and diseases cannot be fully explained by the socioeconomic pattern of each province, this study has not documented the socioeconomic determinants of growth in Iranian 6-year-old children at school entry. As an obvious assumption, it seems to be logical to say that the provinces with the more prevalence of diseases/disorders were economically deprived; however, this prevalence was low in other provinces with a similar socioeconomic situation.

The irregularity in distribution of diseases/disorders across Iranian provinces does not follow the socioeconomic distribution. It means that there is a considerable inequality in the distribution pattern of diseases/disorders. The first explanation for this inequality would be different nutritional and economical patterns among Iranian provinces; however, because in recent decades, Iran has had a big improvement in maternal and child nutritional status, ³ the role of other determinants such as the different pattern of micronutrient distribution across Iran might be more important; in other words, it might be due to recent global economic crisis which it could affect on the accessibility of Iranian families to the enough and necessary amount of foods.

Another explanation for the observed inequality might be the ethnic differences. The populations of various Iranian provinces have their own ethnic distribution. However, these differences are more socioeconomic-related than ethnic differences, because even in provinces with a mixture of ethnic groups, the distribution of observed diseases/disorders is similar to the pattern of provinces with special ethnic groups.

The most important strength of our study is its nationwide coverage of all school-entry children. Another strength is reporting of clinical symptoms′ patterns of children across Iranian provinces. There is also the benefit of using inference statistics; i.e. despite the descriptiveness of previous national health assessments on these children, this study also considered inferential statistics. However, the study had some limitations, its cross-sectional nature being the most important one. In addition, due to very large sample size of the study population, it was not possible to document details of socioeconomic and lifestyle determinants of Iranian children entering school.

The different prevalence distribution of clinical disorders among 6-year-old children across Iranian provinces has been confirmed in this study. These results will raise the necessity of a comprehensive surveillance system and a centralized data registry for Iranian children. Given the variation of growth disorders across different Iranian provinces, information on local circumstances as well as dietary and physical activity patterns of children is essential for policy making at national level.