Risk Factors of Stunting Among Children Aged 6-59 Months In Bensa District ISTRICT, Sidama Region, South Ethiopia: Unmatched Case-Control Study

Background: Stunting remains one of the most common under-nutrition problems among children in the Ethiopia. Children aged 6-59 months share for 35–45% of the burden in endemic areas. Identifying the causes of stunting assists health planners to prioritize prevention strategies, and is a fundamental step for intervention. However, evidence scarce about risk factors of stunting among children aged 6-59 months in study area. Therefore, this study aimed to assess risk factors of stunting among children aged 6-59 months in Bensa district, South Ethiopia; 2019. Methods: A facility-based unmatched case-control study was conducted from January 10 to March 10, 2018 on a sample of 237(79 cases and 158 controls) children aged 6-59 months with their respective mothers. Data were collected using a structured, face-to-face interviewer-administered questionnaire and standard physical measurements. The data were entered using EPINFO version 7 and WHO Anthro software version 3.0.1 and analyzed using SPSS version 20. Chi-square(X 2 ) test was used to determine the overall association between explanatory and outcome variables. The variables were entered to the multivariable model using the backward stepwise regression approach. Multivariable logistic regression analysis was used to identify factors associated with stunting. Adjusted odds ratios (AORs) with a 95% condence interval (CI) were computed to evaluate the presence and strength of associations. Results: Diarrhea in past two weeks (AOR = 2.71, 95% CI: 1.42-5.16) and male sex (AOR = 2.37, 95% CI: 1.224-4.59) were positively associated with stunting. The odds of stunting increased 2.7 times for children who had inappropriate exclusive breast feeding (AOR =2.07, 95%CI: 1.07-4.01) as compared to those who had the appropriate exclusive breast feeding. Having less than or equal to three under ve children in the household (AOR = 2.18, 95%CI: 03-4.64), and mothers had no formal education (AOR =3.28, 95%CI: 1.56-6.924) were positively associated with stunting. Conclusions: Male sex, diarrhea signicant indicating absence of a signicant effect modication. Multicollinearity between the independent variables was also assessed using multiple linear regression. No evidence of multicollinearity was found as the variance ination factor (VIF) for all variables was less than 5 and the tolerance statistic was greater than 0.1. The tness of the logistic regression model was also evaluated in the model using the Hosmer-Lemeshow statistic and greater than 0.05. The presence and strength of association between stunting and the predictors were assessed using adjusted odds ratios (AORs) with a 95% CIs. A statistically signicant association was declared when the 95% CI of the AOR did not contain1.

1.224-4.59) were positively associated with stunting. The odds of stunting increased 2.7 times for children who had inappropriate exclusive breast feeding (AOR =2.07, 95%CI: 1.07-4.01) as compared to those who had the appropriate exclusive breast feeding. Having less than or equal to three under ve children in the household (AOR = 2.18, 95%CI: 03-4.64), and mothers had no formal education (AOR =3.28, 95%CI: 1.56-6.924) were positively associated with stunting.
Conclusions: Male sex, diarrhea in past two weeks, inappropriate exclusive breast feeding, number of the under ve children in the household and mothers had no formal education were major predictors of the stunting. Educating mothers/care takers on Infant and Young Child Feeding practice. Findings support a focus on prevention of diarrhea as part of an overall public health strategy for improving child health and nutrition.

Background
Malnutrition refers to both under-nutrition and over-nutrition. Under-nutrition is "an imbalance between nutrient requirement and intake, resulting in cumulative de cits of energy, protein or micronutrients that may negatively affect growth, development and other relevant outcomes. It is often characterized as acute or chronic [1].
Chronic under-nutrition or stunting re ects a process of failure to reach linear growth potential. It is de ned as a height/length for age is less than − 2 SD of the median of the NCHS/WHO international reference [2].
Ethiopia are fast approaching. Moreover, assessing and identifying the predictors for stunting is important to guide public health planners, policymakers and implementers to plan and design appropriate intervention strategies in order to enhance nutritional status of the children. Therefore, the main aim of this study is to assess presence of chronic diarrhea associated with stunting among children aged 6-59 months in Bensa district, Sidama Region, South Ethiopia.

Study area
The study was carried out in Bensa district, Sidama region, South Ethiopia. The district is located 400 km from Addis Ababa, the capital of Ethiopia. It is also 131 km from Hawassa, the capital of Sidama Region. According to the central statistical agency report of Ethiopia, the total population of the district was estimated to be 310, 952 (8.1 % urban and 91.9% rural). Of these, 13.94 % were children in the age group of 6-59 months. The district has consists of 03 urban and 34 rural Kebeles (smallest administrative unit of Ethiopia). The health service coverage of the district was 94%. There are one-government primary hospital, 11 health centers and 37 health post. It has also consists of 4 private clinics and 12 pharmacies in the districts. According to the health department report, the distribution of stunting affects almost all Kebeles of the district. Agriculture is the main source of income in the district; inhabitants of the district mainly produce enset, cash crops (coffee) and livestock. The total area of the districts is 732.74 . Astronomically, the district is situated between 6.23-6.88 degrees to the north of equator and 38.74-39.09 degrees to the east. The altitude of the district is 1001-2650 meters above sea level. The climatic conditions of district are 47% highland, 35% midland and 18% lowland. Annual temperature is estimated to be between 12.6 -22.5 degree centigrade. Annual temperature is estimated to be between 12.6 -22.5 degree centigrade. Annual range of rainfall is 900-1450 mm with average of 1125 mm [18].

Study design and population
A facility-based unmatched case control study was carried out in Bensa district from January 10 to March 10, 2018. The source population of this study were all children in age group of 6-59 months and mothers/caregivers who utilized EPI and under-ve OPD service in all health facilities. The study population were all selected children in age group of 6-59 months and mothers/caregivers in selected health facilities who have lived with the child at least for 6 months. Those children whose family lived less than 6 months and children who were very sick requiring emergency treatment were excluded from this study.

Sample size determination and sampling technique
The sample size was calculated by using a double population proportion formula in consideration of the following assumptions. The proportion of control in exposure 14.6% and cases in exposure 32.4%, level of con dence 95%, power of the study 80%, ratio of controls over cases 2:1(r=2). Thus, the nal sample size after adding a 10% non-response rate is 237 (79 cases and 158 controls). In Bensa district, there is 1 primary hospital and 11 health centers. One primary Hospital and three Health centers were selected out of eleven health centers by simple random sampling technique (lottery method). The calculated sample size (237) was proportionally allocated to the selected health facilities. A consecutive sampling technique was used to select the study participants until the calculated sample size attained. All children aged 6 to 59 months visiting hospital and health centers during the data collection period were measured for their height. Then, children were categorized as stunted or non-stunted based on calculated z-score value. First, stunted children were identi ed and then selected as cases. The controls were children aged 6 to 59 months without stunting from the same facility cases where selected.

Study variables and data collection technique
The outcome variable was stunting. The independent variables were: socio-demographic variables such as marital status, residence, ethnicity, religion, number of under-ve children, family size, parent's education status, occupation, and economic status: Child characteristics like age, sex, birth order, birth interval, place of delivery, types of birth, and morbidly status (fever, diarrhea and ARI): Child caring practices; such as feeding and immunization: maternal characteristics such as age, mothers' age during rst child, number of children ever has born, ANC visits, use of extra food during pregnancy or lactation and family planning: environmental Health condition like water, hygiene and sanitation.
The data collection was administered by 9 Bsc nurses. One health o cer and the principal investigator intensively supervised the data collection process. The anthropometric data of children were collected by using the measurement of age and height/length. Height was measured using a measuring board by appropriately trained nurses and the child's head, shoulders, buttocks, knees and heels touched the board. Data collection was conducted in a stepwise manner in each health facility in their respective schedule.
Measurement of height was done without shoes; to the nearest 0.1 cm. The raw anthropometric data of the studied children were converted to nutritional indicators using WHO Anthro Software (HFA) by taking sex into consideration. Accordingly, a low height for age, less than -2 SD of the reference population indicates stunting, while less than −3SD indicates severe stunting [3].

Operational de nitions
Stunting (chronic malnutrition): means HFA is below -2 SD of the reference population while below -3 SD indicates severe stunting. Acute Respiratory illness: child with cough and fast breathing or di culty in breathing.
Duration of breastfeeding: the number of months of breastfeeding among children.
Pre-lacteal feeding: a child had given anything to drink other than breast milk in the rst three days after delivery.
Complementary foods: are foods which are required by the child, after six months of age, in addition to sustained breastfeeding.
Diarrhea: a child with loose stools for three or more times in a day.
Family size: refers total number of people living in a house during the study period.
Fever: a child with elevated body temperature than usual.

Data quality control
Data were collected using a structured, face-to-face interviewer-administered questionnaire and standard physical measurements. Firstly, the questionnaire was prepared in English. Secondly, it was translated into Sidama language. Finally, it was retranslated back to English to keep its consistency. The comparison was done to assess the inconsistency and non-accuracy between the two versions of the questionnaire. It was pre-tested on 5% of samples in health facility other than actual study area. Then, any inconsistency and non-accuracy was corrected accordingly. Training was given for data collectors and supervisors by the principal investigator for two days. The training was focused on the objective, methods and data collection process. Regular checkup for completeness and consistency of the data were made on a daily basis.

Data processing and analysis
The data were entered into EPINFO version 7 and WHO Anthro software and analyzed using SPSS version 20. Wealth index was constructed by using Principal Components Analysis in SPSS. All required variables recoding and computations were done prior to the main analysis. Descriptive analyses were conducted to obtain descriptive measures for the socio-demographic characteristics and other variables. Chisquare(X 2 ) test was used to determine the overall association between explanatory and outcome variables. Cross tabulation was used to test the assumption of X 2 .
Binary logistic regression was used to identify predictors of stunting. The bi-variable logistic regression analysis started with unadjusted analysis in which each potential predictor was assessed separately for its association with stunting. Variables with p-values < 0.25 on the unadjusted analysis were entered into a multivariable logistic regression model to nd out independent predictors of stunting adjusting for other factors in the model. The variables were entered into the multivariable model using the backward stepwise regression approach. The main assumptions of the logistic regression model (absence of outlier, multicollinearity and interaction among independent variables) were checked to be satis ed. Accordingly, none of the interaction terms was statistically signi cant indicating absence of a signi cant effect modi cation. Multicollinearity between the independent variables was also assessed using multiple linear regression. No evidence of multicollinearity was found as the variance in ation factor (VIF) for all variables was less than 5 and the tolerance statistic was greater than 0.1. The tness of the logistic regression model was also evaluated in the model using the Hosmer-Lemeshow statistic and greater than 0.05. The presence and strength of association between stunting and the predictors were assessed using adjusted odds ratios (AORs) with a 95% CIs. A statistically signi cant association was declared when the 95% CI of the AOR did not contain1. Informed written permission was also obtained from district health o ce. Informed written consent and child assent was also obtained from each study participant after explaining the objectives, risks/bene ts, rights, con dentiality, nature of the study and the scope of their involvement in the study.

Results
Socio-demographic characteristics of the parents Socio-demographic characteristics of the parents have been summarized in Table 1.
A total of 237 participants were participated in the study with a response rate of 100%.   Of all mothers of children in the cases group, 50 (63.3%) and in the controls group, 118(74.7%) started breastfeeding within the rst one hour after birth. The exclusive breast feeding rate for 6 months were 34 (43.0%) and 106 (67.1%) for cases and controls respectively. There was signi cant variation between cases and controls on duration of exclusive breast feeding (P = 0.001). Meanwhile, the duration of breast feeding was less than 2 years for 46 (58.2%) and 86 (54.4%) of cases and controls respectively.
Concerning immunization status 67 (84.4%) of cases and 146 (92.4%) of controls were vaccinated, and 35(44.3%) of cases and 90(57.0%) of controls were received deworming services. There was no signi cant difference between cases and controls in relation to being immunized (P = 0.066) ( Table 3).  Children of households who used unprotected source of water for drinking accounts 32 (40.5%) and 43 (27.2%) in cases and controls respectively. There was signi cant variation between cases and controls in relation to sources of water (P = .038). Those children households who didn't treat water by any means was found to be 61 (77.2%) in cases and 113 (71.5%) in controls. There was no signi cant difference between cases and controls regards to water treatment method at home (P = 0.349). Majority children of HHs, 73 (92.4%) of cases and 148 (93.7%) of controls have a latrine. There was no signi cant variation between cases and controls in relation to latrine availability (P = 0.714) ( Table 5). This model also showed that children whose mothers have no formal education were 3.28 times more odds of stunted as compared to mother with formal education (AOR = 3.28, 95%CI :1.56-6.924). Moreover, inappropriately exclusive breast feeding (AOR = 2.07, 95% CI: 1.07-4.01) and exposure to diarrhea in past 2 weeks (AOR = 2.71, 95%CI:1.42-5.16) were positively associated with stunting ( Table 6).

Discussion
In this study factors associated with stunting were having less than or equal to three under-ve children in the household, male sex, mothers who had no formal education, inappropriate exclusive breast feeding, and exposure to diarrheal diseases in the last 2 weeks preceding of the survey.
In this study households with less than or equal to three under-ve children is more odds of developing stunting as compared to one under-ve child in the house hold. This nding is similar with the studies conducted in south Ethiopia, Mozambique [19,20]. This might be the fact that as the number of underve children increases in the household the care given to the children decreases, mothers unable to optimally breastfeeding children, causes competition on family resources and increases the risk of infectious diseases [21].
The odds of stunting are signi cantly higher in male children than female. This result is consistent with studies done in Lasta district, and Korahay Zone, Ethiopia, Mozambique and Southwest Uganda [20,[22][23][24]. The cause of this difference in sex requires further study, but variation might be due to sex preference of family. Additionally, it is believed that boys to be biologically more vulnerable to morbidity [25].
Children whose mothers had no formal education were more likely to be stunted as compared to have formal education. This study is in line with studies conducted in Padang city, Indonesia, India, Nairobi, Kenya and Ethiopia [23,[26][27][28]. Mother's education affects the knowledge and attitude of parents which in turn affect their fertility behavior, use of health service and access of nutrition related information. The cumulative effect of these can have impact on prevention of stunting [29].
Inappropriate exclusive breastfeeding signi cantly associated with stunting. This result is agreed with study conducted in Nepal, and South Ethiopia [19,30]. This could be child's digestive and immune systems are not mature before 6 months, and early introduction of complimentary food in unhygienic condition increases diarrheal disease. Furthermore, after 6 months breast milk alone is not su cient to meet the nutritional requirements. Both earlier and delayed introduction of complementary food predisposes the child to increased risks of growth faltering [31].
Children with diarrhea exposure are at increased risk of stunting compared to those with no exposure. This nding is in line with the nding of studies conducted in South Ethiopia, Kenya [32,33]. This might be due to children with diarrhea may have reduced dietary intake, poor absorption of nutrients and increased nutrient loss.

Limitation Of The Study
This study had a number of strengths. Among these, many variables considered to be risk factors of stunting were assessed, valid adapted questionnaires from other studies, and pre-tested questioner was used to collect information, and the case control nature of this study is stronger than cross-sectional study in assessing risk factors which is important to develop relevant policy strategy for e cient prevention of stunting. Regardless of its strengths, our study has some basic limitations that might be considered while interpreting the ndings. First, the study might be prone to recall bias because, the study was questionnaire based require a good memory of mother's/care giver. Second, the study is predisposed to errors of anthropometric measurement that might lead to misclassi cation of children's nutritional status.

Conclusion
Number of under-ve year old children in the household, sex of child, mother's educational status, inappropriate exclusive breast feeding and diarrhea in past 2 weeks were signi cantly associated factors with stunting. Therefore, prevention and control of stunting through improving family planning service utilization should be considered. In addition, intervention should focus on health education for the promotion of appropriate exclusive breast feeding. Moreover, preventing and controlling childhood disease like diarrhea through health extension programs is recommended.