10. The road from 80 to 100

A person's or a cohort's advance from age eighty towards one hundred is of a certain interest because it separates the individuals of true longevity from the merely old in a process which is seen by many as a selection of the fittest or the more robust, by some as an accumulation of wear and tear, and by others as a more complicated and less deterministic interaction of many forces and influences.

        The road from 80 to 100 may be visualized as a long march or an uphill struggle which separates the few successful from the many unsucessful, the graduates from the candidates. Though few of the persons involved would consciously set such a goal for themselves, most of the people in this situation carry on with their daily living with the will or the instinct to survive which is intrinsic in every species.

        Whatever our view, or lact of it, of this process, the simple prosaic figure indicating the probability of an 80-year-old to live to the age 100 is an important indicator of the force of survival in a population. The data will show that the odds in this process, though still overwhelmingly against survival, have lately undergone deep transformations and are in today's low-mortality populations undoubtedly much more favourable than ever before in the history of mankind.

        We have seen in Chapter 5 how the decline in the probability of dying was generally greatest near age 80 and gradually declined with age. Viewed from the opposite angle, that of survival, the change has a totally opposite form: it is smallest near age 80 and grows rapidly as age advances because the ever smaller chances of survival are affected relatively more by even small improvements. For the thirteen countries, the data are given in Table 15 and shown graphically in Figure 20.

        The relative decline in mortality was very much larger for octogenarian women than for men of the same age but their increase in survival, shown in Figure 20, was only narrowly greater than that for men. In mortality decline, the rates of the two sexes merged just before age 100 but in survival increase, the lines cross at age 92 after which the male gains stay higher. As far as it is possible to determine, the survival gains made in the last twenty years seem to reach their maximum values around age 100 - about nine percent for men and seven percent for women.

        Over longer age spans, however, the gains in survival at single ages are compounded and may reach impressive proportions. At high ages, where the chances of further survival are dwindling, even a moderate decline in death rates causes vigorous relative expansion of these chances as becomes manifest from a perusal of  Table 16.

      While the one-year probabilities of survival had increased between two and nine percent, the five-year probabilities increased by between 15 and 50 percent, the highest increases always with the oldest. Exceptions to this rule appear among centenarians, and these may be due either to small numbers or to actually different development. All we really know is that death rates at 100-104 have indeed declined but the precise extent remains uncertain for the time being.

        The chances to survive the entire 80-100-year age span continue to be slim - 0.5 percent for men and 1.5 percent for women even in 1980-90 but they have increased in the last 20 years by no less than 180 percent for each sex.

        A comparison of the three decades, given in the table, shows that the progress in survival has accelerated over this period in every age group of each sex. The logarithmic scale presentation in Figure 21 illustrates the relatively ever wider differences between successive age groups and the likewise relatively faster changes in them over time as well as the special case of longterm survival at the bottom. By coincidence, the men have reached in each case approximately the same survival level as the women had twenty years earlier. To make a finer point, this catching up with women has been slightly more successful for the very oldest.

        An international comparison reveals again substantial differences both in the level and the improvement of the indicator. Table 17 gives the numbers that would survive to age 100 out of 1000 persons of age 80 according to successive decennial life tables. The ratio is given also for countries with not fully reliable data, classified accordingly.

        Until 1970, not even one percent of the 80-year-old in any well-documented population would make it to a full hundred. After 1970, the proportions have increased rapidly, and by the 1980s, the one percent level was surpassed by women in almost all countries while some reached two and Iceland 3.6 percent. The men began in the 1950s mostly at one-promille level and have since made large gains while still remaining far behind women. Very small chances to reach age 100 continue to be recorded in those countries of the former East bloc which produce fully reliable data.

        For greater certainty, we have also tabulated the 80-to-100 evidence for actual cohorts which have already been fully observed over this age span. Joined into groups of ten cohorts each, the data are given in Annex Table 7 and summarized in Table 18. Being necessarily less up-to-date than the latest period data, they show somewhat lower ratios but the overall picture regarding international and gender differentials and the recent trends is the same.

 

Updated by V. Castanova, 1 November 1999