Association between availability of children's book and the literacy-numeracy skills of children aged 36 to 59 months: Secondary analysis of the UNICEF Multiple-Indicator Cluster Surveys covering 35 countries

Background: Stimulating home environments that have children's books, pictures and play toys facilitate caregiver-child interactions and enhance children's development. Although this has been demonstrated in smallscale intervention studies, it is important to document whether book ownership is beneficial at large scale in low and middle-income settings. Methods: We conducted a secondary analysis using data from the multiple- indicator cluster survey, covering 100 012 children aged 36-59 months, from 35 countries. The outcome was children being on-track for a literacy- numeracy index (LNI) constructed from three questions assessing children's ability to identify/name at least 10 letters of the alphabet, read at least four simple popular words and know the names and symbols of all numbers from 1-10. The main exposure was availability of children's book to the child within household. Analysis considered the survey design, assessed and ranked risk ratios of being on track, adjusting for potential confounders such as child's age (in months), maternal education, household wealth index quintile and area of residence (rural/urban). Ecological analysis was performed using meta-regression after grouping countries by World Bank income groups (low- to high-income). Results: Only half (51.8%) of children from all the countries analysed have at least one children's book at home and less than one-third (29.9%; 95% confidence interval (CI) = 23.5%, 36.3%) are on track for literacy-numeracy. After adjusting for confounders, the likelihood of being on track in literacy-numeracy almost doubled if at least one book was available at home compared to when there was none: RR = 1.89 (95% CI = 1.75, 2.03). There was an economic gradient showing that the likelihood of children being on track for LNI decreased with the country's income group: adjusted- RR ranged from 1.65 in upper middle income to 2.23 in LIC (F-test P-value < 0.0001). Only three high-income countries were included, and children's books were universally available resulting in wide confidence intervals for the effect. Conclusions: These findings are policy-relevant, as they corroborate the results from small scale experiments. Making children's book available to children is a cheap and feasible intervention that could change home dynamics to improve the future economic fortunes of children especially in the poorest countries.