ADJUSTED AGE DISTRIBUTION AND ADULT MORTALITY IN SOUTH WEST NIGERIA

Abstract

Globally, Nigeria is one of the countries with high adult mortality. Mortality rate generally is lowest in southwest Nigeria. However, lack of credible data constitutes a challenge to the true estimate of adult mortality in Nigeria including southwest part of the country. The vital registration system that ought to produce reliable estimate of adult mortality in Nigeria is either incomplete or non-existence. Most estimates in circulation do not show the techniques used for their computations and as such subject of criticism. The question to ascertain what a true estimate of adult mortality rate in Nigeria as it compares to the figure for southwest Nigeria where the rate is expected to be the least remains unanswered. Therefore, this study determined the adjusted age distribution and adult mortality in southwest Nigeria. In this study, 2003, 2008, 2013, and 2018 Nigeria Demographic and Health Survey (NDHS) data were used. Also used was age distribution obtained from 2006 Nigeria Census. The estimates of mortality level and adult mortality were obtained through the combination of NDHS data and refined age distribution generated from the 2006 census. MORTPAK LITE was used to estimate childhood mortality based on the information on children ever born and children surviving. Trend in childhood mortality was regressed for 2020 projection. The Y Logit transformation system and Coale-Demeny model life table model was used to adjust for age misreporting between sexes and adult mortality indices estimation respectively. Age misreporting was found among different age groups, but was more prominent among females than males, revealing a similar pattern with the national estimates. The expectation of life at birth was higher for men (64 years), while for females it was 61 years. The probability of dying between age 15 years and 60 years was 0.2218 for males and 0.2371 for females. The probability of dying beyond age 60 years was higher among males (0.6721) than females (0.6370). A decline in mortality experience in the southwest region was found in 2020. Adult mortality rate was high in southwest Nigeria, but the estimate was found to be lower than the that which was obtained at the national level. Females experienced higher adult mortality than males, but the reverse is the pattern for Nigeria. It is important for policy makers to begin to pay attention and mitigate possible threats to adult survival especially among the working population in southwest Nigeria. Keywords: Adult mortality, Life expectancy, Survival probability, Southwest Nigeria