Age Trajectories of Mortality from All Diseases in the Six Most Populated Countries of the South America During the Last Decades

Abstract

Age trajectories of total mortality represent an irreplaceable source of information about aging. In principle, age affects mortality from all diseases differently than it affects mortality from external causes. External causes (accidents) are excluded here from all causes, and the resultant category "all-diseases" is tested as a helpful tool to better understand the relationship between mortality and age. Age trajectories of all-diseases mortality are studied in the six most populated countries of the South America during 1996-2010. The numbers of deaths for specific causes of death are extracted from the database of WHO, where the ICD-10 revision is used. The all-diseases mortality shows a strong minimum, which is hidden in total mortality. Two simple deterministic models fit the age trajectories of all-diseases mortality. The inverse proportion between mortality and age fits the mortality decreases up to minimum value in all six countries. All previous models describing mortality decline after birth are discussed. Theoretical relationships are derived between the parameter in the first model and standard mortality indicators: Infant mortality, Neonatal mortality, and Postneonatal mortality. The Gompertz model extended with a small positive quadratic element fit the age trajectories of all-diseases mortality after the age of 10 years.

Why Does Child Mortality Decrease With Age? Modeling the Age-Associated Decrease in Mortality Rate Using WHO Metadata From 14 European Countries

“…It has to be note that all results and conclusions were limited to the fact that the investigation populations originated from Central, Western and Northern European countries and may not be representative of non-European countries. The partly similar study was done in the six countries of the South America and it had showed that the model of inverse proportion was valid for All causes ATM (specific chapters of ICD10 were not investigated in the study) (23). It indicated that the conclusion of the presented study may be valid in less developed countries.…”

“…The unit corresponding to the mortality rate is "person-years, " which means the number of years lived by members of the population between ages Ai and Bi. Uncertainty or possible demographic error of Li were discussed in the previous studies in detail (20)(21)(22)(23) and they were assumed to be negligible with the respect to resulting ATM. ATM were assumed to be unknown theoretical curves, and were constructed using the right side of the Equation (1).…”

“…It is usually interpreted as a manifestation of aging and affects all individuals (10)(11)(12)(13)(14)(15)(16)(17)(18). From the statistic point of view, age is a deterministic variable in this relationship and coefficients of determination may be higher than 0.99 (4,(18)(19)(20)(21)(22)(23).…”

“…The historical list of studies on this topic is not big and the models are described more detailed in the Appendix (the relationships [17][18][19][20][21][22][23][24]. The exponential Gompertz model used by Thiele was the first historical attempt (30).…”

“…A model of ATM for all age categories was designed later by Heligman and Pollard (7). The simple linear model with two parameters in the log-log scale could be also used and it corresponds to the Weibull distribution [the relationships (23) and (24) in the Appendix]. For example, Bebbington et al used the reduced additive and flexible Weibull distributions with the separation of mortality to exogenous or endogenous causes over the entire life span (8,9).…”