SPATIOTEMPORAL PATTERNS OF INFANT AND CHILD MORTALITY IN NIGERIA, 1990 – 2015

Abstract

High Infant Mortality Rates (IMRs) and Child Mortality Rates (CMRs) are major health challenges in most developing countries, with undesirable socioeconomic consequences. In Nigeria, previous studies have mainly examined the determinants of Infant and Child Mortality (ICM) based on micro level data, with little attention to the spatiotemporal variations at the national level. In addition, the influence of socioeconomic inequalities on IMRs and CMRs nationwide over time has been minimally examined. This study, therefore, was designed to analyse the spatiotemporal patterns and the influence of socioeconomic inequalities on ICM in Nigeria. Mosley and Chen, World Health Organization Social Determinants of Health Models and Concept of Health Equity constituted the framework. State-level data on ICM, child’s sex, antenatal care, breastfeeding, vaccination, wealth index, religion, education and age of mothers were derived from the 2003, 2008 and 2013 Nigeria Demographic and Health Surveys and annual World Bank datasets (1990-2015). The extracted data were linked to their corresponding spatial units for geospatial analysis. Descriptive statistics, Moran’s Index, Getis-Ord Gi* Statistic, ANOVA, Stepwise regression, Rate Ratio (RR) and Rate Difference (RD) were used for the analysis at p0.05. IMRs were 81.944.6 (2003), 69.418.7 (2008) and 60.617.8 (2013) per 1000 live births, whileCMRs were 47.036.3 (2003), 37.719.9 (2008) and 23.614.6 (2013) per 1000 children surviving to age one. Both IMRs and CMRs declined over time in Bayelsa, Borno, Kaduna and Ekiti States. The IMRs increased in Imo, Oyo, Anambra, Abia, Lagos, Yobe, Kebbi and Sokoto States, while CMRs increased in Imo, Cross River, Delta and Katsina States. The IMRs were clustered but insignificant for all periods, while CMRs were significantly clustered in 2003 (0.40), 2008 (0.56) and 2013 (0.53). The hot spots of IMRs and CMRs were mainly among states in the Northwest and Northeast while cold spots were mainly among states in the Northcentral and Southwest geo-political zones. The IMRs (F(2;108)=4.82) and CMRs (F(2;108)=8.01) varied significantly over time across states. Wealth Index, breastfeeding duration and antenatal care explained most of the variations onIMRs and CMRs in 2003 (R2=0.54; 0.54), 2008 (R2=0.46; 0.66) and 2013 (R2=0.64; 0.73) at the state level. Most of the annual variations in IMRs and CMRs (1990-2015) (R2=0.99; 0.99) were accounted for by rates of vaccination, urbanization and inflation.Socioeconomic inequalities on IMRs and CMRs increased mainly in states in the Northeast and Southsouth geo-political zones. Between wealth groups, inequalities markedly increased for infant mortality in Yobe (RR: 1.35 to 7.07; RD: 16 to 58 per 1000 live births) and for child mortality in Benue (RR: 1.05 to 3.58; RD: 2 to 23 per 1000 children surviving to age one). Contiguous states in Nigeria have similar or near similar rates of Infant and Child Mortality and these are influenced mainly by the Wealth Index. High and increasing socioeconomic inequalities onInfant and Child Mortality persist, despite significant reductions in mortality rates over time. Implementation of place - and group - specific strategies in tackling Infant and Child Mortality while regularly evaluating their impact is required.