This study used secondary data collected from the fourth round of the National Family Health Survey (NFHS-4), conducted in 2015–16. A cross-sectional study was designed in this study.
Sample size and procedure
All living under-five children (n=247,743) who participated in the NFHS-4 were enrolled in the study. The NFHS-4 is a nationally representative large-scale sample survey carried out across all the states and union territories of India. The samples were selected using a two-stage stratified sampling design. In the first stage, the clusters were selected using the method of probability proportional to size. In the second stage, complete household mapping and listing have been done in the selected clusters and 22 households were randomly selected from each cluster. The sampling frame used in this survey was the 2011 Indian Population and Housing Census. A detailed description of the sampling design and survey procedure is provided in the NFHS-4 national report .
The outcome variable of this study is diarrhoeal disease in children under five. Diarrhoea is defined as having three or more loose or watery stools in 24 hours, as reported by the mother/caregiver in the past two weeks preceding the survey.
Socio-demographic and environmental characteristics were included for explanatory variables in this study. The operational definition and coding of variables are included in Table 1. Socio-demographic characteristics include place of residence (rural and urban), caste (scheduled castes/scheduled tribes, other backward classes, and others), religion (Hindu, Muslim, and others), maternal education (illiterate/primary and secondary/above) father’s education (illiterate/primary and secondary/above), maternal age (15–24, 25–34 and 35–49 years), maternal body mass index [BMI] (underweight, normal and obese), access to mass media (no and yes), household size (<6 and 6+), wealth quintile (poorest, poorer, middle, richer and richest), region (north, central, east, northeast, west, and south), age of the child (0–11, 12–23, 24–35, 36–47 and 48–59 months), sex of child (male and female), birth order (1, 1–3 and 4+) and birth weight (<2.5 kg [low birth weight] and ≥2.5 kg [normal]).
Environmental characteristics include the availability of toilet facility, sources of drinking water, child stool disposal, and main floor and roof materials of the household. Household toilet facility was a dichotomous variable, classified as households having a toilet facility and households without a toilet facility. Any improved, unimproved, and shared latrine facility (flush or pit) were considered as households having a toilet facility, otherwise households using open defecation. Sources of drinking water were categorized as improved and unimproved sources. Improved sources of drinking water are protected from outside contamination, particularly from fecal matter . Improved sources include piped water, public taps, standpipes, tube wells and boreholes, protected dug wells and springs, rainwater, and community reverse osmosis plants, while unimproved sources comprise unprotected dug well, unprotected spring, tanker/cart with a small tank, surface water, and bottled water. Child stool disposal was grouped into safe and unsafe disposal. Children’s stool was considered to be safely disposed, if a child used a toilet or latrine, or flushed into a toilet, or it was buried . The main floor materials of the houses were categorized as dirt (e.g., mud/clay/earth, sand, and dung) and non-dirt (e.g., raw wood planks, palm, bamboo, brick, stone, parquet or polished wood, vinyl or asphalt, ceramic tiles, cement, carpet and polished stone/marble/granite). Likewise, the main roof materials of the dwelling unit were grouped into thatch (e.g., thatch/palm leaf, mud, plastic/polythene, rustic mat, palm/bamboo, timber, etc.) and metal/concrete (e.g., metal, wood, asbestos sheets, cement/concrete, tiles, slates, burnt bricks, etc.).
Descriptive statistics were carried out to understand the distribution of socio-demographic and environmental characteristics for the study sample. The prevalence of diarrhoeal disease was estimated by selected explanatory variables. Pearson’s chi-square test was used and variables with p<0.05 were included for further analysis. The sample weight was used for the estimation of percentage distribution. Bivariate and multivariate logistic regression models were employed to assess the socio-demographic and environmental factors associated with diarrhoea in children under five. The regression results are presented by unadjusted and adjusted odds ratio (OR) with 95% confidence interval (CI) and the results were considered to be statistically significant at p<0.05. All the statistical analyses were performed using STATA version 14.0 (StataCorp LP, College Station, TX, USA).