In 2016, a children's health study was conducted, monitoring both the children's health and levels of chemicals in the body. The study included a questionnaire survey aimed at allergic diseases, obesity, cardiovascular risk factors, and locomotor disorders in childhood. The questionnaire also contained questions about eating habits. Blood and urine samples for the analysis of selected biomarkers of exposure to chemicals and nutritional biomarkers were collected from children of five cities. The study was supported by the Society of General Paediatricians.

The monitoring was conducted during the preventive check-ups of children aged five, nine, 13, and 17 years in surgeries of 46 general paediatricians in selected cities (Praha, Brno, České Budějovice, Jihlava, Olomouc, Hradec Králové, Liberec, Jablonec nad Nisou, Ústí nad Labem, Kladno, Mělník, Hodonín, Ústí nad Orlicí, Žďár nad Sázavou, Sokolov, Most, and Kutná Hora) of the Czech Republic (CR). The participating paediatricians were selected with respect to the city size to obtain a representative sample of about 1,500 children in each age group. The children were included in the study at random by the paediatrician when presenting for preventive check-ups according to the month of birth. Each participating paediatrician was supposed to examine 30 children from each age category, i.e. 120 children in total. Anonymized check-up data and other data, particularly on allergic diseases, were provided based on parental informed consent. The data on the child's diseases and life style were taken from the parental questionnaire.

The samples of biological material for analyses of foreign (lead, cadmium, mercury, arsenic, and phthalate metabolites) and beneficial substances (selenium, iodine, and vitamin D) were collected from five-year-old and nine-year-old children in selected cities  (Prague, Liberec, Ostrava, Žďár nad Sázavou, and Kutná Hora). 

1.      Allergic diseases

Overall, data on 6,329 children were available for the purposes of standard assessment of the incidence of allergic diseases and their trends in the CR. Boys and girls were equally represented (51% of males and 49% of females). Each age group (5, 9, 13, and 17 years) comprised around a quarter of the cohort under study.

A total of 1,861 children, i.e. 29% of the study cohort, were physician diagnosed with an allergic disease (and followed up for allergy). The incidence of allergic diseases was increasing with increasing age from 22% in five-year-olds to 35% in 17-year-olds. Males were significantly more affected (32%) by allergic diseases in general and by respiratory allergy in particular than females (27%) (p < 0.001). The incidence of different allergic diseases is indicated in Tab. 1.

 Tab. 1 Prevalence rate of allergic diseases in children, 2016

* some children have multiple allergic diseases

Ten percent of children were diagnosed with asthma. Boys were more often affected than girls, and the incidence of asthma was increasing with increasing age. Based on the asthma control test administered to 222 asthma patients aged 13 and 17 years, about half of the respondents achieved full asthma control, 41% partial asthma control, and 12% poor asthma control.

Thirteen percent of children were diagnosed with seasonal pollen rhinitis. Significantly more patients were boys, and the incidence of seasonal pollen rhinitis was increasing with increasing age. The incidence of year-round allergic rhinitis is also significantly higher in boys and is increasing with increasing age.

Ten percent of children were diagnosed with atopic eczema, comparably in both sexes and all age groups.

Three percent of children were diagnosed with food allergy based on testing, comparably in both sexes and all age groups. Based on the parental data, eight percent of children develop an allergic reaction to certain foods, but only a quarter of them tested positive for food allergy. The most common was the reactivity to various fruits (kiwi, citrus fruits, apples, or strawberries), vegetables (most often tomatoes), nuts, dairy products, and chocolate.

The factors causing allergy based on skin tests or IgE antibodies were grass pollen, mites, birch tree pollen, and herbal pollen.

The trends in allergic diseases in childhood can be determined since 1996 when the monitoring was started. Between 1996 and 2006, there was a significant increase in the prevalence of allergic diseases from 17% to 32% (p<0.001). The increase stopped in 2011, and the prevalence showed a slight decrease to 30% (p=0.007). The prevalence of allergic diseases was 29% in 2016, being the same as in 2011. The prevalence of allergic diseases did not change in any age groups since the previous investigation. The only change was observed for atopic eczema, the prevalence of which slightly declined from 11% in 2011 to 10% in 2016 (p=0.037).

2.      Respiratory problems

The parents reported respiratory problems in their children during the last year, particularly acute inflammation of the upper respiratory tract and bronchi, and problems unrelated to common colds or acute disease. Frequent episodes of upper respiratory tract inflammation (more than five episodes per year) were reported in one in four children and even in one in three in the youngest, five-year-old children. These problems were significantly more common in children whose parents reported the presence of heavy traffic or an industrial source of pollution close to the place of residence or who lived in smoking households. Frequent acute bronchial inflammation with general symptoms (fever and/or irritant cough, more than three episodes per year) were reported in 10% of children, and the most affected were once again the smallest children. The negative effect of the sources of pollution situated near the place of residence as reported by parents was also demonstrated. In smoking households, recurrent episodes of bronchial inflammation were only slightly more common than in non-smoking households, but the children in the former households were more frequently treated with antibiotics. A significantly higher prevalence of eye and nose irritation and wheezing unrelated to colds was found in children whose parents reported the presence of heavy traffic or an industrial source of pollution near the place of residence or lower quality of the indoor environment (smoking households or indoor moulds).

3. Blood lipid levels

 Atherosclerosis can begin as early as in childhood and its extent is influenced by cardiovascular risk factors, such as hypercholesterolemia, obesity, hypertension, and cigarette smoking. Since 1992, five-year-old and 13-year-old children with a positive family history have also been tested for lipid profile (total plasma cholesterol level, LDL cholesterol, HDL cholesterol, and triglycerides). The results are included in their medical records and the children at risk of developing cardiovascular disease (CVD) are referred to specialists. Within the study, 740 children were tested. The average levels were 4.25 mmol/l for total cholesterol, 2.51 mmol/l for LDL cholesterol, and 1.43 mmol/l for HDL cholesterol.  The average levels of all indicators were significantly lower in boys than in girls. The highest average levels of total cholesterol and LDL cholesterol were found in the smallest, five-year-old children and are physiological at this age. The blood cholesterol levels in children were divided into three categories based on [Šamánek, M., Urbanová, Z. Twenty years of cardiovascular risk prevention in Czech children. Cor et Vasa 2014;56, 163–167]: optimal levels were found in 60% of children, borderline levels in 26% of children, and pathological levels in 14% of children.

The average blood triglyceride level (1.00 mmol/l) found in children falls in the range of borderline levels (1.0 – 1.5 mmol/l) and was comparable in both males and females. Altogether 12% of children had pathological levels of triglycerides. Older children had significantly higher levels than the younger ones , which probably reflect the age-related changes in eating habits and frequency of physical activities.

Pathological levels of total cholesterol and LDL cholesterol were more often recorded in girls while boys had higher triglyceride levels. Obese children had significantly higher blood lipid levels in comparison with normal weight children. Pathological triglyceride levels were found in 28% of obese children and in 10% of normal weight children.

4. Blood pressure

 Blood pressure was measured in all children when presenting for a preventive check-up. It was part of the so-called population screening, with the reading made during a visit to the doctor. Whenever the first reading was higher than the blood pressure values corresponding to the 90^th percentile for the given age and gender, the paediatricians were asked to make two more readings (during the ongoing preventive check-up). Blood pressure was measured by the auscultatory method in 2,478 children. Based on [2], the children were assigned to categories. Ninety percent of children had normal blood pressure, 6% had high-normal blood pressure, and 4% had blood pressure in the hypertension range. The prevalence of high blood pressure or hypertension was slightly increasing with increasing age from 3% in five-year-olds to 5% in 17-year-olds, but the differences were not statistically significant. Neither were there significant differences between boys and girls. Blood pressure in the range of hypertension was recorded in 3% of normal weight children, 4% of overweight children, but in 15% of obese children.

5.  Body weight

 Body weight assessment in children is made using the percentile Body Mass Index (BMI) charts, which indicate whether a child's weight is proportional to his/her height and age. Based on weight, the children were assigned to four categories. Of the study cohort, 8% of children were underweight, 74% were normal weight, 8% were overweight, and 10% were obese.

Slightly more boys than girls were overweight or obese. The proportion of overweight/obese children was increasing with increasing age: between the ages of five and nine years, the number of overweight/obese children sharply rose, and the highest number of overweight/obese children was among 13-year-olds.

Since 1996 when the monitoring started the number of overweight/obese children was increasing until 2011. The results from 2016 show that the upward trend stopped and the number of overweight/obese children tends to be stabilized.

6.  Locomotor system condition in children

 The posture was assessed based on the paediatrician's data on the spine curvature in the sagittal plane, spine curvature in the frontal plane (scoliotic posture and scoliosis), and general posture rated using a 4-point scale. A physiological posture characterized by the physiological spine curvatures in both the sagittal and frontal planes was classified as excellent or good. Children who failed to meet the criteria for physiological posture were diagnosed with postural abnormalities. Such abnormalities were found in 42% of children, more often in boys (46%) than in girls (38%)  (p<0.001). The proportion of children with postural abnormalities was increasing with increasing age from 27% in five-year-olds to 54% in 13-year-olds, but it dropped to 44% in the oldest, 17-year-old children as a result of an increase in muscle mass supporting the skeletal system. Underweight and overweight/obese children had significantly more often postural abnormalities than normal weight children.

 The most common postural abnormalities were forward head (26% of children), roundback/thoracic kyphosis (14%), and scoliotic posture (13%). Forward head and roundback were more common in boys, and there was no difference in the prevalence of scoliotic posture between boys and girls. All these three abnormalities were the most common in 13-year-old children. Seventy-nine children (1.5 % of the study cohort) were diagnosed with scoliosis, and the most affected were the 17-year-olds.

Based on the parental data, one in five children (21%) experiences occasional headaches, reported significantly more often in girls than in boys. The number of children with headaches was increasing with increasing age, and the most affected were 17-year-olds (35 %); one in five teenagers experiences at least one headache per week. Headaches were reported more often in children with postural abnormalities in comparison with those with a physiological posture. Neck pain was reported by parents in 7% of children, similarly to lower back pain; half of these children experience both neck and lower back pain. The prevalence of back pain was increasing with increasing age and was higher in girls.

7.  Physical activities and eating habits

Regular organized sports activities are practised by about half of children (54%) participating in sports and leisure groups, with the nine-year-olds being the most active (72%) and the 17-year-olds the least active (37%). The children participating in sports activities spend 3.9 hours per week on average practising sports. The time spent participating in sports activities is increasing with  increasing age from two hours per week on average in five-year-olds  to  5.8 hours per week in 17-year-olds. Most children participate in sports activities once to three times per week. No difference was found in the participation in organized sports activities between boys and girls.

Sixty-seven percent of children participate in more or less regular unorganized sports activities at least once a week, with the nine-year-olds accounting for the highest percentage (74%) and the 17-year-olds for the lowest percentage (60%). Children spend 4.5 hours per week on average participating in unorganized physical activities, ranging from 5.1 hours per week for the five-year-olds  to 3.9  hours per week for the 17-year-olds, and practise these activities most often once to three times per week.

Twenty percent of children do not participate in either organized or unorganized sports activities.

Children spend 2.2 hours per day in front of the computer, tablet, or TV on average, ranging from 1.5 hours a day for the five-year-olds to twice as much time, i.e. 3.2 hours a day for the 17-year-olds. One in four children spends more than three hours a day in front of these electronic devices and one in ten children more than four hours a day. Boys spend significantly more time in front of the PC/TV than girls (p<0.001). Children who spend more than two hours a day in front of the PC/TV have statistically significantly more often forward head (p=0.001), headaches (p<0.001), neck pain (p<0.001), and lower back pain (p<0.001). Children who spend more than two hours a day in front of the PC/TV significantly more often (p<0.001) eat fast food and drink soft drinks and are more often overweight or obese (p<0.001).

Fifteen percent of children eat less than one portion of fruit a day ranging from 10% in five-year-olds to the double percentage in the 17-year olds. Even worse outcomes were achieved for eating vegetables: One in four children eats less than one portion of vegetables a day (from 20% of five-year-olds to 29% of the 17-year-olds). Eleven percent of children drink three or more soft drinks a day; this indicator showed the smallest differences between age categories. Six percent of the five-year-olds and 20% of the 17-year-olds eat fast food more than once a week. One in ten children eats fast food even twice or three times a week. Overweight/obese children less often eat fruit (p=006) and vegetables (p=0.001), but more often drink soft drinks (p=0.016) and eat fast food (p<0.001) in comparison with normal weight children. Boys eat significantly less fruit and vegetables (p<0.001), drink more soft drinks (p<0.001), and eat more fast food (p=0002) than girls, but the genders did not differ in the consumption of confectionery.