Diversity & Equality in Health and Care Open Access

Social Inequality and Overweight in German Primary School Children: A Cross-Sectional Analysis

Susanne Kobel^*, Lina Hermeling, Christine Lämmle, Olivia Wartha and Jürgen M. Steinacker ¹Department of Medicine, Ulm University, Leimgrubenweg, Germany
^*Correspondence: Susanne Kobel, Department of Medicine, Ulm University, Leimgrubenweg, Germany, Email:

Received: 29-Jun-2022, Manuscript No. IPDEHC-22-13926; Editor assigned: 01-Jul-2022, Pre QC No. IPDEHC-22-13926 (PQ); Reviewed: 15-Jul-2022, QC No. IPDEHC-22-13926; Revised: 20-Jul-2022, Manuscript No. IPDEHC-22-13926 (R); Published: 27-Jul-2022, DOI: 10.21767/2049-5478.19.7.31

Introduction

Inactivity and unfavorable lifestyle trends lead to adverse sys- temic and mental health outcomes worldwide and in all social strata. A growing number of young people is physically inactive and frequently as a consequence suffering from overweight and obesity [1,2]. High body weight very often tracks from childhood into adulthood [3]. Current prevalence of childhood overweight and obesity is substantial in many countries, but large variations between and within countries exist. In general, prevalence is higher in developed countries [4].

In 2016, over 340 million children and adolescents worldwide were overweight or obese [5]. Since 1975, the prevalence of overweight and obesity has risen from four to over 18% in 2016 and is continuously increasing in most countries [5]. The obesity prevalence among children has always been lower compared to adults, but the growth rate is higher. Childhood obesity is associated with several non-communicable diseases such as cardio-vascular diseases, certain forms of cancer and type 2 diabetes mellitus, inflammation, and is a significant early threat for adult morbidity and mortality [2,6].

For children as for adults, migration to western countries in- creases the risk of overweight and obesity [7]. Variations in overweight prevalence between migrant and non-migrant pop- ulations may be due to epi-genetic predisposition as well as environmental and behavioral factors. Immigrants often have been exposed to specific experiences, which can be passed to their offspring, starting from infancy and even intrauterine life [8]. However, not only the process of migration, but also settlement in the new home country involves risks in terms of lifestyle related diseases. Traditional nutrition habits are aban- doned while westernized patterns such as high contain of salt, sugar and fat are adopted [9]. Especially migrants coming from poorer to wealthier countries show elevated obesity preva- lence rates due to these environmental and behavioral changes [10]. A longer period of stay is thus associated with higher prev- alence rates of overweight and obesity (Waters et al., 2008). In addition, societies of developing countries often have a cultural preference for higher bodyweight as sign of wealth [11].

In 2020, 26.7% of the total population in Germany had a mi- gration background [12]. This percentage is rising every year. A large representative study in Germany has shown that children with a two sided migrant background are generally at higher risk of becoming obese than those with a one sided or no mi- grant background [13]. Another high risk factor for overweight and obesity for children in industrialized countries is a low so- cioeconomic status (SES) [14,15].

In a study of 997 first graders in Germany, children with a low SES and migration background were more likely to show unfa- vorable health behavior patterns, higher BMI scores and poor- er motor skills [16]. Differences in SES do not seem to be able to explain those inequalities sufficiently [15].

The interplay between cultural and socioeconomic factors remains unclear and it has to be further examined, whether migration background is a proxy for SES regarding weight sta- tus, or whether there is an independent effect. This cross-sec- tional study aims to investigate the interplay between cultur- al background, SES (i.e. educational background and income) and childhood overweight in order to better comprehend the potential for variation in future intervention strategies and to finally reduce health inequalities.

Methods

The evaluation is designed as a cross-sectional investigation. Baseline data from the cluster randomized Baden-Württem- berg primary school study were evaluated [17]. The study was approved by the ethics committee of Ulm University (Applica- tion No. 126/10) and is registered at the German Clinical Trials Register, German Institute of Medical Documentation and In- formation [DRKS-ID DRKS00000494].

Participants

A total of 1968 parents gave their written informed consent for their children to take part in the study. 1956 children, be- tween six and nine years of age, visiting primary schools (1st and 2nd grade) in Baden-Württemberg, southwest Germany were examined. In the data processing, 310 children were ex- cluded since information on country of origin was not available from both parents. Accordingly, 1646 schoolchildren (7.1 ± 0.6 years, 50.1% male), of which 489 have a migration background, are included in the statistical analysis. Questionnaire data were available from 1714 parents.

Data Collection

Children’s weight status includes Body Mass Index (BMI), BMI percentiles and Waist to Height Ratio (WHtR). Examinations were performed according to the standardized procedures by trained examiners in small groups of children, separated by gender [18,19]. Measurement of body weight was performed using calibrated flat scales (Seca^® 826, Hamburg, Germany) in minimal clothing. Height was measured barefoot with mo- bile stadiometers (Seca^® 217, Hamburg, Germany). Waist cir- cumference was measured halfway between the lower costal border and the iliac crest using a metal tape measure (Lufkin^® W606PM, Lufkin Industries Inc., Texas, USA). Children’s BMI was calculated (kg/m2). BMI percentiles (BMIPCT), based on German and international cut off criteria, were used to classify children into overweight or obese [20-22]. In addition, WHtR as a measure of central obesity (WHtR>0.5) was calculated.

Level of academic and professional education and monthly net income from both parents were assessed within the parental questionnaire. Family level of education was categorized ac- cording to the adjusted “Comparative Analyses of Social Mo- bility in Industrial Nations” (CASMIN) classification [23]. Levels were dichotomized into tertiary and elementary/intermediate level of education. Household monthly net income was as- sessed on a seven point scale and dichotomized into <1750 € and ≥ 1750 €.

Children were identified as having a migrant background if they wereborn abroad or at least one parent was born abroad [12]. A distinction between children with one and two sided migrant background was made. Further, three migrant groups were specified, based on geographical location: from Turkey, from Eastern Europe, and from other countries. Children not having a migration background were titled “native”.

Analysis

Data evaluation was performed using IMB SPSS Statistics 22 (SPSS Inc., Chicago, IL, US). Significance level was set to α<0.05. Socio-demographic characteristics of the sample were de- scribed, categorized into migrant and native children and fur- ther subdivided into parental origin (Germany, Turkey, Eastern Europe and other). Overweight and obesity prevalence, ac- cording to national and international cut-off points and World Health Organization [21,24]. WHtR and socioeconomic factors were reported. Pearson’s Chi²-Test and Mann Whitney U-Test were used to reveal group-differences. Binary logistic regres- sion was employed to analyze strength and direction of asso- ciations between weight status, SES, cultural background and parental weight status.

Regressions were run separately for each explanatory variable and also block wise with forced entry, adjusted for age, gen- der and parental BMI. Results were presented as odds ratios (OR) with 95% confidence intervals (CI). Possible joint effects of cultural background and socioeconomic factors on childhood overweight were examined.

Results

Of the 1646 children included in the analysis, 489 (29,7%) had at least one parent, who was born abroad in one of 62 coun- tries represented. 50.1% of the children were male and the ma- jority were 5, 6 or 7 years of age (99.1%), the mean age of the sample was 7.1 (± 0.6) years. 76.8% of the mothers and 76.5% of the fathers were born in Germany. From those parents who were born abroad, most came from Eastern Europe (51.3% and 47.1%, respectively) or Turkey (22.3% and 26.6%, respectively). In 23.3% of the families, one of the parents spoke another lan- guage than German to the child. There was no family in which none of the parents was able to speak German. Descriptive characteristics of the study population are shown in Table 1.

Table 1: Descriptive characteristics of the study population

The overall sample prevalence of overweight including obesi- ty was 18.5% and 5.0% for obesity alone (according to WHO reference values) as shown in Table 2 [9]. For children with migration background, the prevalence was 26.7% and 7.9%, respectively. No gender differences either for overweight in- cluding obesity or obesity alone could be detected. The mean BMI z-score (WHO) was 0.14 (± 1.08).

Table 2: Prevalence of overweight (and obesity) defined by German and international cut-off points

Parental BMI

Children’s overweight was positively associated with paren- tal BMI (p<0.001). With a mother being overweight or obese, children had a 42.7% higher risk of being overweight or obese (CI 1.247-1.633, p<0.001). Almost the same was true for the fathers (OR 1.436, CI 1.232-1.673, p<0.001). Having one over- weight or obese parent in general increased the odds by 82.8% (CI 1.257-2.651, p<0.01). Being a child of two overweight or obese parents increased the chance of being overweight by 269.5% (CI 2.471-5.528, p<0.001). Therefore, analyses were adjusted not only for age and gender, but also for parental BMI.

Socioeconomic Position

Overweight including obesity was negatively associated with parental education and family income (Table 3). Children of parents with low or medium education were 55.3% more likely to be overweight or obese compared to the reference popu- lation (CI 1.113-2.167, p=0.01). Children of families with a net income <1750 € had 96.2% higher odds of being overweight (CI 1.316-2.924, p=0.001) compared to children from families with a higher income.

Table 3: Final binary logistic regression model

Parental Origin

Children whose parents emigrated from Turkey exhibited the highest overweight prevalence (34.8%, p < 0.001). Children of mothers born in Turkey carried the highest risk being almost twice as likely to be overweight or obese compared to children with native parents (OR 1.916, CI 1.316-2.789, p=0.001). In addition, a father born in Turkey elevated the odds (OR 1.749, CI 1.235-2.477, p<0.01). No significant differences were found across the other groups of origin as shown in Table 4.

Table 4: Prevalence and risk estimates for overweight (including obesity)

The ANOVA revealed no significant differences between one and two sided migration background concerning BMI, BMIPCT, z-score and WHtR. However, differences between no and one sided migration background (BMI p<0.01, BMIPCT p<0.05, z-score p<0.05, WHtR p<0.05) and between no and two sid- ed migration background (BMI p<0.01, BMIPCT p<0.01, z-score p<0.01, WHtR p<0.05) were detected. Differentiating for paren- tal country of origin, the group with Turkish parental origin dif- fers from the native group in BMI, BMIPCT, z-score and WHtR, according to the Kruskall-Wallis Test (maternal origin: BMI p<0.001, BMIPCT p<0.001, z-score p<0.001, WHtR p<0.01; pa- ternal origin: BMI p<0.001, BMIPCT p<0.001, z-score p<0.001, WHtR p<0.001).

The final analysis was adjusted for age, gender and parental BMI. The Pearson Chi² test shows a strong association between childhood overweight (WHO) (p < 0.001) and maternal cultur- al background (χ²(3)=28.705, p<0.001), using the four catego- ries: Germany, Turkey, Eastern Europe and other. This is also true for central obesity (WHtR<0.5), but only in girls [maternal background: (χ²(3)=22.542, p<0.001); paternal background: (χ²(3)=30.409, p<0.001)].

In the final binary logistic regression model, having a migra- tion background and a family net income below 1750€ showed to be relevant risk factors on childhood overweight (Table 4). Children with a migration background had an 81.9% higher risk of being overweight (CI 1.323-2.502, p<0.001) while children coming from a family with low income had a 114.9% higher risk (CI 1.422-3.247, p<0.001). The combination of both revealed no significant effect, showing that the two factors are inde- pendently related to childhood overweight.

Discussion

The interplay between cultural and socioeconomic factors is still unclear in scientific literature. In the present cross-section- al study, anthropometrical, socio-economic and cultural factors were assessed in a large, statewide sample of families in south- west Germany. The results show a higher prevalence of over- weight and obesity among children with migration background compared to children of German born parents. A similar find- ing was observed for children from low income families. These effects showed to be independent from each other.

In this sample, the overall prevalence of overweight including obesity was 18.5% and 5.0% for obesity alone. Prevalence in children with migration background was 26.7% and 7.9%, re- spectively. Another large study from Germany revealed similar observations with an overweight prevalence among migrant children of 12.7% compared to 6.9% among non-migrant chil- dren [25]. Numerous international studies also found a higher prevalence of overweight and obesity in migrants in general [21,26,27]. However, such comparisons are not necessarily practical since countries differ in their migration history and origin of immigrants. In addition, the definition of migration background is not uniform. Different reference values for child- hood overweight and obesity make the evaluation even more difficult.

Parameters such as SES, duration of stay and immigrant gener- ation are not assessed routinely. Therefore, the effect of migra- tion on overweight was possibly underestimated in the present study, since children and adolescents from the first immigrant generation have been shown to have a lower prevalence of overweight (13.6%) than those from the second or third im- migrant generation (22.6%) [28]. Findings reveal that not all groups of migrants are affected by overweight and obesity in a similar manner. In the present sample, children from parents born in Turkey had an elevated risk of being overweight or obese whereas children from parents born elsewhere did not differ significantly from the native reference group. In Germany and the Netherlands, children from parents originating from Turkey have been identified as a high risk group for childhood overweight [29]. In the Netherlands, children and adolescents aged 0-21 years from Turkish (n=2904) and Moroccan (n=2855) origin had a higher overweight prevalence compared to their Dutch counterparts (n=14500) [29]. The overweight prevalence in Turkish boys and girls was 23.4% and 30.2%, in Moroccans 15.8% and 24.5%, for Dutch adolescents in large cities 12.6% and 16.5%, and for other Dutch participants 8.7% and 11.3%, respectively. Also, in the Dutch ABCD cohort (n=3871), girls from mothers with Turkish and Moroccan origin were at a high- er risk of early weight gain during infancy (0-3 years) already [30]. In Austria, anthropometric data of 1786 children aged six, 10, and 15 years were collected, showing that children from Turkey but especially from former Yugoslavia display an elevat- ed weight status [31]. In order to determine whether this effect is genetic, cultural or a result of acculturation, comparable data on childhood overweight prevalence in Turkey would be useful. Unfortunately, there is no large scale nationwide study on prev- alence of childhood obesity in Turkey available. Several local studies performed between 2001 and 2011 in different regions of Turkey have shown varying prevalence rates of (8.3%-22.4%) (1.6%-10.6%) for overweight (and obesity) in 2-18 year olds with a peak before puberty [32]. Obviously, those numbers cannot be compared to the present study outcome due to the huge variations in subject sampling.

In the present study, overweight including obesity was nega- tively associated with parental education and family income. Children of parents with low or medium education were more likely to be overweight or obese compared to the reference population. Children of families with a low income had an ele- vated risk of being overweight. These findings correspond with former scientific work [33] However, this can only be observed in developed countries. In developing countries the effect works inversely [14]. Even though Turkey has an industrializing economy, evidence suggests that obesity is more prevalent in children of higher SES in Turkey which contrasts to studies exe- cuted in Germany and other westernized countries [34].

Although this study has a large sample size, which increases the likelihood of having sufficient power to detect differences, some aspects should be considered when interpreting these findings. As every study, this study faces potential sources of bias. First, the parental questionnaire was only available in German, which could have led to a response bias and a mis- classification of SES due to language deficits of some respon- dents. Consequently, there was no family in which none of the parents spoke German. Second, a non-response bias might have occurred due to avoidance of anthropometric measure- ments by overweight children and parents, which might have led to a reduction of effect estimates. Further, parental height and weight was based on self-report, which might have led to downward bias and misclassification of weight status. Howev- er, this type of bias is consistent across gender, age and ethnic groups [35,36] Another source of misclassification might have been the primary use of the “2007 WHO growth reference for school age children and adolescents” for classification of chil- dren’s weight status [9]. It is designed for children and adoles- cents aged 5-19 years but have not been widely used, which makes it difficult to compare prevalence rates on an interna- tional or even on a national basis. Nevertheless, it was possible to compare and analyze differences between subgroups of the sample. The WHtR, as a measure of central obesity, was ob- jectively measured in this sample by trained stuff according to the ISAK-standards, which makes up a notable strength in data acquisition [20,32]. Parental data were analyzed from both mother and father. Moreover, it was not only differentiated for migrant or native, but also for origin country of each of the parents. Unfortunately, data about second or third immigrant generations was not obtained. Linear relationships between immigrant generation and weight status could not be detect- ed. The CASMIN-index is a one-dimensional indicator of educa- tional level. As parental education plays a particular role in the development of childhood overweight and obesity, decompo- sition of SES components (e.g. education, income, professional qualification) gives a more detailed picture than a multidimen- sional index. The three categories for non-native respondents (Turkey, Eastern Europe, other) or even dichotomization (mi- grant/non-migrant) partly failed to describe the diversity in mi- grant groups. However, the case numbers of 489 children with migration background with parents from 62 different countries did not offer another statistically sound option. Oversampling of non-native children and parents could prevent this prob- lem in future studies. However, the total sample size in this study (1946 children and their parents) is remarkable. Consid- ering the large sample size and the high response rate, it can be assumed that the sample is representative for the state of Baden-Württemberg and southwest Germany.

Conclusion

Overweight and obesity are largely preventable conditions and at the same time difficult to cure. This study strengthens the perception that migration background and low family income are substantial risk factors for childhood overweight. Beyond that, it could be detected that migration background does not serve as a proxy for family income and vice versa, regarding childhood overweight risk. This offers a new perspective for fu- ture intervention designs and analyses as both factors can be addressed independently. For further studies, the inclusion of a greater variety of socioeconomic indicators is advised as well as nationwide, representative samples. Effective public health policies need to consider the social gradient in health as well as intra-cultural differences, which are present already in child- hood in order to avoid further possible health inequalities.

Acknowledgements

The school based health promotion program ‘‘Join the Healthy Boat’’ and its evaluation study is financed by the Baden-Würt- temberg foundation, which had no influence on the content of this manuscript. This work is part of Lina Hermeling’s doctoral thesis and the authors would like to thank all members of the research group for their input. We also thank all assistants who were involved in the performance of measurements and espe- cially all children and their parents for their participation. This study was supported by a grant from the Baden-Württemberg foundation. The funder had no role in study design, data col- lection and analysis, decision to publish, or preparation of the manuscript. No competing financial interests exist.

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