Lecture 4.

Historical interest in mortality.
Inaccuracies in cause-specific death statistics.

1. Some causes are reported with greater care than others, for instance cardiovascular events vs. suicides.
2. Unattended deaths by physicians often require a postmortem analysis since the cause of death is not immediately ascertainable.
3. Blatant falsification of records occurs.
4. Historically there was a tendency to lump ill-defined causes into the catchall category of unknown on natural causes. Over time number of causes of death identified increased, and accuracy of diagnosis improved reducing size of unknown category.
5. Multiple causes with a primary cause not clearly specified often lead to inaccuracies.
6. Reluctance of medical and legal communities to recognize multiple causes of morbidity or death, i.e., multiple chemical syndrome or Gulf War syndrome. Ironically clusters of single causes were noted occurring in combination researchers identified symptoms of alcoholism or AIDs.

1. Immaturity (newborn infants of less than 2,500 grams).
2. Congenital malformations.
3. Birth injuries.
4. Postnatal asphyxiation.
5. Nutritional maladjustment in early infancy.
6. Pneumonia.
7. Gastritis, diarrhea, duodentitis, and enteritis.
8. Accidents.
9. Infective and parasitic diseases.

1. Simple and very inexpensive programs were instituted to separate sewage from water supplies, boil water, place dwellings and campsites away from stagnant water and insects that carry diseases, and wash before eating and after elimination.
2. Introduction of high-tech and high cost technology to reduce deaths due to the genetic, gestational, and post parturition conditions.

1. Changes in infant mortality have dramatic effects on life expectancy values.
2. Infant mortality is highly correlated with the crude birth rate.

1. Every industrial nation now is grouped in the low mortality category. Future improvements in the death rate will be minor.
2. Campaigns against epidemics and infectious diseases have drastically reduced mortality rates in Africa, Asia, and Latin America. In most instances, countries within each of these regions that exhibited a rise in the level of living also show a decline in mortality.
3. Barriers most difficult to over come in reducing mortality are malnutrition, poverty, and illiteracy.

The logic of the single decrement life table is simple. It takes a hypothetical group of persons called a cohort (typically 100,000) and subjects members to the current force of mortality, derived from a schedule of age-specific death rates, and decrements these persons from birth, age by age, as they mature until all persons in the initial cohort have died. Except in the very young ages losses are presumed to be evenly distributed between one exact birthday and the next. The initial cohort is presumed closed to migration.

The life table technique permits the calculation of the probability of dying (q_x) between exact age x and exact age x+n, the number of deaths (d _x) between age x and x+n, the number of survivors (l_x) from age x to x+n, the number of years lived by survivors (L_x) at each age, the total number are person-years lived (T_x) at each age or above age x, and the average number of years remaining to persons (e_x) between birth and at each age.

The life table may be seen as analogous to Hume’s constructed bridge called the bridge of life and death crossing a frozen river. The span of the bridge represents the human life span in years lived. The span is subdivided, so that the distance between each successive pair of points represents one year of life between 1 exact birthday in the next exact birthday. Between each pair of points on the bridge span, there is a specially constructed trapdoor. The size of each trapdoor is predetermined by the age-specific death rate for that year of life. When the trapdoor is sprung, it will drop the predetermined number of cohort members through the bridge to the icy surface below. The cohort proceeds across the bridge of life and death moving one year at a time. Between each age and age x+n and the trapdoor springs open, the dead fall to the surface below and the survivors continue on their track. We can calculate the number of deaths that occur in each age and the survivors at each age, the distance traveled by survivors along the bridge to each age, the total distance traveled by cohort survivors at each age, and the average distance traveled by cohort’s survivors from birth or at each age.

Single decrement, double decrement, multiple decrement, increment-decrement life tables.
Uses of each technique.
Hazard analysis with large Ns versus risk analysis with mall Ns.
The mortality curve as biological law.
Discussion of survivorship L_x sloped curve versus rectangular.

Patterns of dying by sex.

Sex ratio at conception, at birth, in youth, middle age. When does SR become feminine?

Patterns of dying by occupation.

Extractive industrial jobs-- fishing, logging, mining, & farm. Transportation jobs-- Pilots, taxi cabs, machine operators, truckers. Police and fire. Managerial and Professional jobs. Note real estate broker is most likely occupation to suffer attack among managerial & professional jobs.

Patterns of dying by season.

Water borne diseases. Respiratory and communicable diseases. Historical shifts.

Patterns of dying in rural and urban.

City --> Rural. Early cities Empire cities, Medieval cities. Rural --> City. Late industrial.

Epidemiological transition theory.

Omran versus later articulations.