Estimation of the Family and Community Unobserved Heterogeneity Effects on the Risk of Under-Five Mortality in Nigeria using Frailty Model


  • Anthony I. Wegbom Department of Mathematics, Rivers State University, Port Harcourt, Nigeria
  • Isaac D. Essi Department of Mathematics, Rivers State University, Port Harcourt, Nigeria
  • Victor A. Kiri Department of Mathematics, Physics & Electrical Engineering, Northumbria University, Newcastle Upon Tyne, UK



Under-five mortality, Unobserved heterogeneity, Frailty model, Determinants, Nigeria.


The Under-five mortality (U5M) rate is an important determinant of societal and national advancement- a key marker of wellbeing, value, and access. In spite of efforts to identify the predictors of U5M to reduce its high level in Nigeria, the problem remains a major cause for concern. This study estimated the potential role of unmeasured/unobserved factors at both family and community levels, using shared frailty models on the 2013 Nigeria Demographic and Health Survey (2013 NDHS) data. The Log-rank test was used to identify variables associated with U5M- hazard ratio estimates with P<0.05 were considered as statistically significant. Our findings suggested region, marital status, place of residence and place of delivery were significant determinants of U5M in both frailty models. We also found evidence of frailty effect on the risk, particularly at the community level- heterogeneity due to unmeasured/unobserved factors, which are generally ignored when we assess the risk using only observed variables. We, therefore, suggest that to achieve the sustainable development goals relating to child health in Nigeria, more significant efforts should be directed at identifying more determinants, such as to reduce the influence of unobserved factors and facilitate an extension of interventions to these factors.


McGuire JW. Basic health care provision and under-5 mortality: a cross-national study of developing countries. World Dev 2006; 34(3): 405-25.

Khan JR, Awan N. A comprehensive analysis on child mortality and its determinants in Bangladesh using frailty models. Archives of Public Health 2017; 75: 58.

UNICEF. Levels and Trends in Child Mortality Report 2017. Estimates Developed by the UN Inter-agency Group for Child Mortality Estimation [cited 2018 Oct 20]. Available from:

United Nations. Transforming our World: the 2030 Agenda for Sustainable Development. United Nations. [cited 2018 Oct 20]. Available from: doc.asp?symbol=A/RES/70/1&Lang=E.

National Population Commission (NPC) [Nigeria] and ICF International. Nigeria Demographic and Health Survey, 2013. Abuja, Nigeria, and Rockville, Maryland, USA 2014.

UNICEF. Levels and Trends in Child Mortality: Report 2014. Estimates Developed by the UN Inter-agency Group for Child Mortality Estimation [cited 2018 May 12]. Available from:

National Population Commission (NPC) [Nigeria] and ICF International Nigeria Demographic and Health Survey 2018 Key Indicators Report. Abuja, Nigeria, and Rockville, Maryland, USA 2019.

Wegbom AI, Essi ID, Kiri VA. Survival Analysis of Under-five Mortality and Its Associated Determinants in Nigeria: Evidence from a Survey Data. Int’l J of Stat and Appl 2019; 9(2): 59-66.

Akinyemi JO, Bamgboye EA, Ayeni O. New trends in under-five mortality determinants and their effects on child survival in Nigeria: A review of childhood mortality data from 1990-2008. Afri Pop Studies 2013; 27(1): 25-42.

Adedini AA, Clifford O, Eunice NSI, Dorothy NO, Latifat I. Regional variations in infant and child mortality in Nigeria: A multi-level analysis. J Biosoc Sci 2015; 47: 165-87.

Adebayo SB, Fahrmeir L. Analyzing Child Mortality in Nigeria with Geoadditive Survival Models. Sonderforschungsbereich 2002; Paper 303.

Kayode GA, Adekanmbi VT, Olalekan A, Uthman OA. Risk Factors and a predictive model for under-five mortality in Nigeria: evidence from Nigeria demographic and health survey. BMC Pregnancy and Childbirth 2012; 12(10): 1-10.

Adebowale SA, Morakinyo OM, Ana GR. Housing materials as predictors of under-five mortality in Nigeria: evidence from 2013 demographic and health survey. BMC Pediatrics 2017; 17: 30.

Wegbom AI, Akinyemi JO, Edet CK. The Influence of Frailty on Infant and Child Mortality in Rural Nigeria. American J of Public Health Research 2018; 6(1): 21-25.

Omariba DWR, Beaujot R, Rajulton F. Determinants of infant and child mortality in Kenya: an analysis controlling for frailty effects. Popul Res Policy Rev 2007; 26(3): 299-321.

Nasejje JB, Mwambi HG, Achia TN. Understanding the determinants of under-five child mortality in Uganda including the estimation of unobserved household and community effects using both frequentist and Bayesian survival analysis approaches. BMC Public Health 2015; 15: 1003.

Akinyemi JO, Bamgboye EA, Ayeni O. Trends in neonatal mortality in Nigeria and effects of bio-demographic and maternal characteristics. BMC Paediatics 2015; 15: 36.

Antai D. Regional Inequalities in Under-five Mortality in Nigeria: A Population-based Analysis of Individual - and -Community Determinants. Pop. Health Metrics 2011; 9(6): 1-10.

Antai D, Ghilagaber G, Wedrén S, Macassa G, Moradi T. Inequities in under-five mortality in Nigeria: differentials by religious affiliation of the mother. J of Relig Health 2009; 48(3): 290-304.

Uthman OA. Effect of low birth weight on infant mortality: Analysis Using Weibull Hazard Model. The Int J of Epidemiol 2008; 6 (1): 8-16.

Wegbom AI, Aboko IS, Mandah OCA. Multivariate Analysis of Child Mortality determinants in Rural Nigeria. Int. J of Multi Discipline in Ind and Appl Sci 2016; 1(8): 1-10.

Wegbom AI, Wokoma DSA, Nnoka LC, Chibo O. What explains the high rate of infant mortality in rural Nigeria: biodemographic or socioeconomic factors? Int J Health Sci Res 2016; 6(8): 317-23.

Pedersen J, Liu J. Child Mortality Estimation: Appropriate Time Periods for Child Mortality Estimates from Full Birth Histories. PLoS Med 2012; 9(8): e1001289.

Wegbom AI, Kiri VA and Essi, ID. Comparison between Semi-Parametric Cox and Parametric Survival Models in Estimating the Determinants of Under-Five Mortality in Nigeria: Application in Nigerian Demographic and Health Survey. Afr J of Maths and Stat Stud 2019; 2(2): 1-12.

Kleinbaum, D, Mitchel K. Survival Analysis: A Self-Learning Text.3rd ed. Springer Science + Business Media, Inc. 2012.

Joshua K, Jeroen K. Determinants of infant and child mortality in Zimbabwe: Results of multivariate hazard analysis. Demographic Research 2009; 21(13): 367-384.

Morakinyo OM, Fagbamigbe AF. Neonatal, infant and under-five mortalities in Nigeria: An examination of trends and drivers (2003-2013). PLoS ONE 2017; 12(8): e0182990.

Kazembe L, Clarke A, Kandala NB. Childhood mortality in sub-Saharan Africa: cross-sectional insight into small-scale geographical inequalities from Census data. BMJ Open 2012; 2: 1-12.

Dejene T, Girma E. Social determinants of under-five mortality in Ethiopia: Event history analysis using evidence from Ethiopian Demographic and Health Survey (EDHS). Health (Irvine. Calif) 2013; 5: 879-84.

Tekelab T, Chojenta C, Smith R, Loxton D. The impact of antenatal care on neonatal mortality in sub-Saharan Africa: A systematic review and meta-analysis. PLoS ONE 2019; 14(9): e0222566.

Rahman A, Rahman S, Rahman A. Determinants of infant mortality in Bangladesh: a nationally surveyed data analysis. International Journal of Child Health & Nutrition 2019; 8(3): 93-102.






General Articles