Theory of the age dependence of mortality from congenital defects

Why Does Child Mortality Decrease With Age? Modeling the Age-Associated Decrease in Mortality Rate Using WHO Metadata From 25 Countries

Background: Our previous study analyzed the age trajectory of mortality (ATM) in 14 European countries, while this study aimed at investigating ATM in other continents and in countries with a higher level of mortality. Data from 11 Non-European countries were used. Methods: The number of deaths was extracted from the WHO mortality database. The Halley method was used to calculate the mortality rates in all possible calendar years and all countries combined. This method enables us to combine more countries and more calendar years in one hypothetical population. Results: The age trajectory of total mortality (ATTM) and also ATM due to specific groups of diseases were very similar in the 11 non-European countries and in the 14 European countries. The level of mortality did not affect the main results found in European countries. The inverse proportion was valid for ATTM in non-European countries with two exceptions. Slower or no mortality decrease with age was detected in the first year of life, while the inverse proportion model was valid for the age range (1, 10) years in most of the main chapters of ICD10. Conclusions: The decrease in child mortality with age may be explained as the result of the depletion of individuals with congenital impairment. The majority of deaths up to the age of 10 years were related to congenital impairments, and the decrease in child mortality rate with age was a demonstration of population heterogeneity. The congenital impairments were latent and may cause death even if no congenital impairment was detected.

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

Background: Mortality rate rapidly decreases with age after birth, and, simultaneously, the spectrum of death causes show remarkable changes with age. This study analyzed age-associated decreases in mortality rate from diseases of all main chapters of the 10th revision of the International Classification of Diseases. Methods: The number of deaths was extracted from the mortality database of the World Health Organization. As zero cases could be ascertained for a specific age category, the Halley method was used to calculate the mortality rates in all possible calendar years and in all countries combined. Results: All causes mortality from the 1st day of life to the age of 10 years can be represented by an inverse proportion model with a single parameter. High coefficients of determination were observed for total mortality in all populations (arithmetic mean = 0.9942 and standard deviation = 0.0039). Slower or no mortality decrease with age was detected in the 1st year of life, while the inverse proportion method was valid for the age range [1, 10) years in most of all main chapters with three exceptions. The decrease was faster for the chapter "Certain conditions originating in the perinatal period" (XVI).The inverse proportion was valid already from the 1st day for the chapter "Congenital malformations, deformations and chromosomal abnormalities" (XVII).The shape of the mortality decrease was very different for the chapter "Neoplasms" (II) and the rates of mortality from neoplasms were age-independent in the age range [1, 10) years in all populations. Conclusion: The theory of congenital individual risks of death is presented and can explain the results. If it is valid, latent congenital impairments may be present among all cases of death that are not related to congenital impairments. All results are based on published data, and the data are presented as a supplement.

Modeling the Age-Associated Decrease in Mortality Rate for Congenital Anomalies of the Central Nervous System Using WHO Metadata From Nine European Countries

Background: In humans, the mortality rate dramatically decreases with age after birth, and the causes of death change significantly during childhood. In the present study, we attempted to explain age-associated decreases in mortality for congenital anomalies of the central nervous system (CACNS), as well as decreases in total mortality with age. We further investigated the age trajectory of mortality in the biologically related category "diseases of the nervous system" (DNS). Methods: The numbers of deaths were extracted from the mortality database of the World Health Organization (WHO) for the following nine countries: Denmark, Finland, Norway, Sweden, Austria, the Czech Republic, Hungary, Poland, and Slovakia. Because zero cases could be ascertained over the age of 30 years in a specific age category, the Halley method was used to calculate the mortality rates in all possible calendar years and in all countries combined. Results: Total mortality from the first day of life up to the age of 10 years and mortality due to CACNS within the age interval of [0, 90) years can be represented by an inverse proportion with a single parameter. High coefficients of determination were observed for both total mortality (R2 = 0.996) and CACNS mortality (R2 = 0.990). Our findings indicated that mortality rates for DNS slowly decrease with age during the first 2 years of life, following which they decrease in accordance with an inverse proportion up to the age of 10 years. The theory of congenital individual risk (TCIR) may explain these observations based on the extinction of individuals with more severe impairments, as well as the bent curve of DNS, which exhibited an adjusted coefficient of determination of R ¯ 2 = 0.966. Conclusion: The coincidence between the age trajectories of all-cause and CACNS-related mortality may indicate that the overall decrease in mortality after birth is due to the extinction of individuals with more severe impairments. More deaths unrelated to congenital anomalies may be caused by the manifestation of latent congenital impairments during childhood.

Decrease of total activity with time at long distances from a nuclear accident or explosion

Two data groups were analyzed: (1) the exposure rate in the former Czechoslovakia after the Chernobyl accident in 1986, and (2) the decrease of beta activity of an atmospheric fallout sample taken in Bratislava during 24 h on 30 May 1965. Both quantities decreased with the first power of time. This pattern of decrease is explained by applying the same mathematical formalism as is also used to describe the decrease in postnatal mortality with age. Following this formalism, the decrease of total activity with the first power of time could be seen as a consequence of a log-normal distribution of decay constants in the fallout. This differs slightly from earlier results that show the total activity decreasing with a power of 1.2 immediately after the nuclear explosion.

The decline of postnatal mortality from gastrointestinal anomalies with age

It has been previously shown that mortality from congenital anomalies decreases with the first power of age with the exception of "gastrointestinal anomalies". On the other hand, mortality declines with the second power of age in the category "certain conditions originating in the perinatal period". According to the theory of congenital individual risks, the dying out of more impaired individuals causes these two types of mortality decline. Mortality decline with the first power of age is the most frequent type of mortality decline after birth. This evidence is explained as a consequence of the rule: the higher the individual risk of death, the less frequent the individual risk is at the moment of birth. If all defects (and all individual risks) appear with the same frequency and selection does not occur (e.g. this could be assumed for certain conditions originating in the perinatal period) then mortality declines with the square of age. Here, it is shown that mortality from "gastrointestinal anomalies" (ICD9 codes: 750 and 751) decreases with the second power of age in all five countries within the age interval 1-10 years. This is a consequence of evidence that these defects do not affect vitals important during pregnancy and selection is not significant. These findings demonstrate that the selection of higher individual risks proceeds during pregnancy rather than during previous generations.