Rural-urban determinants of vitamin a deficiency among under 5 children in Bangladesh: Evidence from National Survey 2017–18

Background Vitamin A supplementation reduces child morbidity, mortality, and blindness of people, especially in developing countries like Bangladesh. This study explores significant determinants of vitamin A deficiency among preschool children in rural and urban areas of Bangladesh. Methods The data set was extracted from a nationally representative survey based on a cross-sectional study, the BDHS-2017-18. The base survey was conducted using a two-stage stratified sample of households. A sample of 8364 (urban 2911, rural 5453) children under-5 years old was analyzed using bivariate and multivariate statistical techniques. Results Results have demonstrated that 73.9 and 73.2% of children have had a vitamin A supplementation from urban and rural areas, respectively. Logistic regression analysis showed that parents’ education plays a vital role in consuming vitamin A supplements in urban and rural areas. Children whose mothers have secondary (OR: 1.17, CI: 0.76–1.81) and higher (OR: 1.21, CI: 0.72–2.04) education were more likely to consume vitamin A supplementation than children whose mothers were illiterate in urban areas. However, in rural areas, children whose mothers have secondary education were about 24% and higher education with 60% more likely to consume vitamin A supplementation than children whose mothers were illiterate. Child’s age, regional variation and wealth index also contributing factors for vitamin A deficiency in Bangladesh. Conclusions These findings indicated that the consumption of vitamin A does not cover the target of sustainable development goals. Thus special national and community level efforts are required to ensure the coverage of the national vitamin A program is increased adequately to the most vulnerable groups of children in Bangladesh.


Introduction
Vitamin A is an essential nutrient needed in small amounts and mainly required for the visual system, growth and development, maintaining epithelial cellular integrity, immune function and reproduction [1]. Inadequate intake of vitamin A is the primary root of vitamin A deficiency (VAD). Nowadays, VAD is one of the most important concerns among the public health problems since many children, and pregnant women are affected by Vitamin A deficiency disorder throughout the developing countries including Bangladesh [2,3]. Moreover, the Vitamin A deficiency (VAD) disorders reduce the immune competence, which is responsible for increasing the morbidity and mortality associated with night blindness, corneal ulcers, keratomalacia and related ocular signs and symptoms xerophthalmia [4][5][6][7][8][9]. Vitamin A deficiency is also associated with an increased risk of child mortality and of a range of problems, including measles, diarrhea, respiratory diseases, vision problems, and can lead to death [2,[10][11][12][13][14][15]. The evidence above ensures that the prevalence of many childhood diseases is more common among stunted children, and on the other hand, there is a significant association between stunting and VAD [16]. Vitamin A deficiency in under-five children can also cause mortality risk up to 20-30% [17]. Also, Xerophthalmia among preschool children amounts to about 5 million cases, 10% of which can potentially lead to blindness in India [18,19]. Globally, about 30% of children under the age of 5 years are vitamin A deficient, and about 2% of all deaths are attributable to VAD in this age group [14,20]. The most important agenda of Sustainable Development Goal-3 is to reduce the preventable deaths of under-five children at least as low as 25 per 1000 live births within 2030 [21] and reduce the number of stunted children under five by 40% by 2025 [22]. Therefore, vitamin A supplementation was suggested to reduce child morbidity and mortality from various diseases; however, it would be treated as a costeffective strategy for reaching SDG-3 [23].
Since the vitamin A supplementation program is a cost-effective approach to lessen the burden of VAD, it is necessary to design the community-based vitamin A supplement program considering associated factors that significantly enhance the awareness among underprivileged people and the consumption rate of vitamin A supplementation (VAS) [24][25][26][27]. Existing literature riched by such studies that have been conducted to identify the determinants that are significantly associated with the VAS program in several countries. Abedin et al. (2019) mentioned that age, sex, religion, mother's education, immunization status for the vaccine-preventable disease are associated with the recent receipt of VAS [21]. Mostafa et al. (2019) try to determine the factors affecting low coverage of the VAS program among the young children admitted to a diarrheal hospital of Bangladesh and age of the child, parental education, and wealth status are associated with receiving the vitamin A supplement. They also observed an increase in coverage of VAS from 61 to 76% over the last 18 years [20]. Muliyil et al. (2019) mention that the educational status of the household head was significantly associated with an increased risk of VAD among children [28]. Other studies across the world also reveal that age, sex, BMI, religion, age of mother, mother's education, family type, occupation, income, food habits, type of residence, access to media, wealth index, and social development status of their state of residence are associated with recent receipt of VAS [2,[29][30][31][32][33][34][35].
However, in light of the existing literature, a substantial research gap has been discovered in this topic, particularly in Bangladesh. Therefore, to fill this gap, the authors were motivated to conduct a study to ascertain the influential determinants of VAD in urban-rural settings of Bangladesh based on the most recent BDHS-2017/18 survey data. To assess the association between the children's vitamin A capsule consumption status and socio-economic and demographic characteristics, we used the Chi-square test in the bivariate analysis. Moreover, the logistic regression analysis was carried out to determine the effects of the covariates on the response variable.

Data sources, study design and participants
This study considers a secondary dataset collected from a county representative entitled Bangladesh Demographic and Health Survey (BDHS)-2017-18. The sampling frame of this survey was the list of enumeration areas (EAs) of the 2011 Population and Housing Census of the People's Republic of Bangladesh. The primary sampling unit of this survey was an EA. The survey used two-stage stratified sampling techniques. In the first stage, 675 EAs were chosen, with 227 and 448 EAs from urban and rural areas. However, data was not possible to collect from 3 EAs due to natural disasters. These clusters were in Dhaka (one urban cluster), Rajshahi (one rural cluster), and Rangpur (one rural cluster). In the second stage of sampling, a systematic sample of 30 households selected from each EA. As a result, 20,250 residential households were selected into the four phases. Among the 20,376 ever-married women age 15-49 years eligible for interviews, 20,127 were interviewed, yielding a response rate of 99%. A sample of 8364 children aged under-5 years (5453 and 2911 from rural and urban areas, respectively) was used for the subsequent analysis. The Details of the sampling procedure are available on the report of the Bangladesh Demographic and Health Survey-2017-18 [36].

Variables
This study aims to measure the prevalence of vitamin A capsules consumption by under-5 years' old children in rural and urban areas of Bangladesh. The following question was asked to the child's mother "did your child consume vitamin A capsule within the last six months?" to assess the consumption of vitamin A capsule. This question's outcome is considered as the dependent variable, which is a dichotomous variable indicating whether a child consumed vitamin A or not. Moreover, the socio-economic and demographic characteristics like age of the child (in months), child's sex, region/division, religion, number of children, mother's age, mother's education, father's education, sex of household head, wealth index and breastfeeding status included in the subsequent analysis as a set of covariates.

Statistical analysis
The Chi-square test is employed to determine the significance of exposure variables with the target variable, and logistic regression analysis is used to determine the influence of the selected covariates on the response variable. The results presented in odds ratios (ORs), with 95% confidence intervals (95% CIs). The IBM SPSS version 25 was utilised in all statistical analyses.
The logistic regression model [37,38] can be expressed as, where, Y i is a binary variable that takes a value of ' 1 ' if the respondent received the vitamin A capsules and ' 0 ' otherwise, X i is a vector of independent variables and β is a vector of unknown parameters which contains the intercept parameter and the regression parameters associated with a set of covariates used in the study. The fitted form of the model can be defined as, where,β l ðl ¼ 0; 1; 2; …; kÞ represents the estimated regression coefficient of the l th independent variable in the study.

Results
This section offers empirical data analysis results with descriptive interpretations.  Table 1]. The age of the child and religious status factors are significantly related to the consumption status of Vitamin A capsules in both urban and rural areas. Looking at the age group of 6-12 months, 70.6% of children in rural areas have consumed vitamin A capsules whereas, in the urban area, only 69.7% of children had consumed vitamin A capsules. This result indicates that the child lives in urban and rural areas are same likely to consume vitamin A supplement, however, in the previous survey, the child who lived in rural areas were more vulnerable to vitamin A deficiency-related diseases than child lived in urban areas. Parental education plays a vital role in vitamin A consumption by their child. Both in rural and urban areas, vitamin A consumption increased with the increase of wealth index. Breastfeeding children were less consuming vitamin A capsules than their counterparts [ Table 1].
The prevalence of vitamin A consumption was more than 90% in the 1996-97 survey. It increased around 95% in the 1999-2000 survey for boys and girls in urban and rural areas of Bangladesh. After the year 2000, the rate of receiving the vitamin A supplement by children decreased dramatically for all groups. In 2004, the prevalence of vitamin A consumption of urban boys and girls was slightly higher than rural boys and girls. The lowest figures observed in 2011 for all categories, and then the estimates increased a bit in the 2014 survey, especially for the estimates of both boys and girls in urban areas. The vitamin A coverage again increased in 2018 compared to the previous survey year 2014, both in urban and rural areas among both sexes. In general, findings demonstrated that girls received more vitamin A capsules than boys, and the prevalence of receiving vitamin A was slightly more in urban areas than in rural areas of Bangladesh. An overall downward trend of the prevalence of vitamin A consumption is observed with some fluctuations for 1996 to 2018 by the child's sex and rural-urban status (see Fig. 1).
The bar graph presented in Fig. 2 depicts the comparison of receiving the vitamin A supplement in the last 6 months by the urban-rural setting of different age groups of children from 1996 to 2018. In the age category of 6 months to 1 year, the prevalence was almost double in 1996-96 and 1999-2000 than the remaining years. A slight variation is observed by region as well as Mother's education ( a***, b** ) the age of the child. Surprisingly the overall rate of consumption of vitamin A supplements has been decreased in recent years for children aged between one and 5 years (see, Fig. 2). Also, for the age group of 6 months to 1 year, this study observed the lowest percentage of the child received vitamin A capsules in the last one and half decades in urban and rural areas of Bangladesh.
In urban areas of Bangladesh, children aged 13-24 months (OR: 2.33; CI: 1.56-3.42) and 25-36 months (OR: 0.82; CI: 0.57-1.19) were more and less likely to consume vitamin A in comparison to the age group 6-12 months respectively. The results revealed that with the increasing age of a child, consuming vitamin A supplements decreases in both urban and rural areas. Children whose mothers have secondary (OR: 1.17, CI: 0.76-1.81) and higher (OR: 1.21, CI: 0.72-2.04) education were more likely to consume vitamin A supplementation than children whose mothers were illiterate in urban areas (see in Table 2). However, in rural areas, children whose mothers have secondary education were about 24% (OR: 1.24, CI: 0.92-1.68) and higher education with 60% (OR: 1.60, CI: 1.07-2.38) more likely to consume vitamin A supplementation than children whose mothers were illiterate. Somewhat similar results were observed for the father's education. These results depict that parents education play a vital role in the  Table 2].

Discussion
This study demonstrated the significance of potential socioeconomic and demographic factors associated with vitamin A supplementation among under-5 children in the settings of rural and urban areas of Bangladesh. It is found that the children residing in different divisions (administrative regions) have a varying percentage of receiving vitamin A capsules-leading the division as a significant factor for receiving vitamin A capsules. This finding is also supported by another study [21]. The authors think that this variation is due to the demographic and socio-economic diversity among divisions. In this study, urban children from middle-class families are more likely to receive vitamin A supplementation than others because Bangladeshi middle-class families are more concerned about their children. Subsequently, children from the wealthiest family have a slightly higher chance of vitamin A consumption in rural and urban areas. This finding is consistent with the result of a previous study [21,30]. Children's age is another contributing factor, and this study revealed that the children of age group 13-24 months are higher likely to receive vitamin A capsules. However, after 24 months, children are less likely to consume vitamin A capsules than 6-12 months aged children in urban and rural areas. These results are probably due to the assorted carrying attitudes of parents or caregivers to their offspring in different age groups. However, Janmohamed et al. (2017) and Agrawal and Agrawal (2013) found that all age groups are equally likely to consume vitamin A capsules [30,39].
This study demonstrated that parental education was key determinants for receiving vitamin A capsule in Bangladesh's rural and urban areas, which was a consistent finding with other [2,29]. This study found that in rural areas, children whose mother and father having higher educational qualifications (i.e., secondary and higher) are more likely to consume vitamin A capsules. However, it observed a different result in urban areas, i.e. children whose father and mother had the primary education were more likely to consume vitamin A capsules. It could be because a higher educated parent in an urban area remains busy with other activities except for their parenting task. Therefore, parents' awareness of their children may be more effective in reducing the VAD burden [20,25]. The educated parents' having enough knowledge about vitamin A-rich food also plays a crucial factor in preventing the vitamin A deficiency of their offspring. A study found a significant positive association between maternal education VAS attendance in Cambodia [40]. The families having three or more children were more likely to consume vitamin A supplementation in rural and urban areas of Bangladesh. It is because elder offspring sometimes look after their younger siblings among families having more children. The authors believe that the quality of the data ensures the acceptance of the findings.

Conclusions
This study depicted that vitamin A supplementation coverage for the urban and rural areas is 73.9 and 73.2%,  respectively, which indicates that to achieve the SDGs target, we have to prioritise and improve the vitamin A campaign in Bangladesh. Findings also suggest that vitamin A supplementation is less in rural areas than the urban areas. Moreover, the results are varied significantly with region, religion, wealth index, children's age, mother's age, mother's education, and father's education in the rural area. This study examined the nature and determined the essential determinants of children's vitamin A supplementation intake. The significant factors identified in this study will be helpful for the researcher to identify other related factors to reduce child mortality due to vitamin A deficiency. Since the human body cannot produce vitamin A, it must be included in our diet. Therefore, the authors strongly recommended consuming a regular intake of vitamin A-rich foods such as liver, chicken, beef, eggs, oily fish, milk, mangoes, orange fruits, sweet potatoes, carrots, spinach, and other green vegetables. It is also suggested that mothers should breastfeed their child as it contains vitamin A which is essential for young children. Moreover, various fortified foods with vitamin A, like cereals, slices of bread, pastries, and crackers, may be used to supplement vitamin A. An improvement of dietary intake of vitamin-A may enhance the vitamin A status among under-5 children. Thus, dietary intake, including the foods mentioned earlier, will be considered an alternative approach to taking vitamin A supplements to prevent vitamin A deficiency.
Moreover, these findings would assist decision-makers to design effective policies that could improve some of the risk determinants, especially in the rural area, to increase concern for vitamin A supplementation. There may be a spatial variation in the data at local area levels, which could help developing precision policy and the most effective implementation [38]. The future study should focus on expanding the analysis to include other explanatory variables such as geospatial attributes related to child health and using the up-to-date data. Future research can also employ a multi-level modeling approach for minimizing any higher-order variations in the data [37,41]. Finally, it may better understand the dynamics of vitamin A coverage in other Southeast Asian countries. *p < 0.10; **p < 0.05; and ***p < 0.01