6. Growing numbers of old people
During the early stages of the mortality transition the death rates did not change very much at old age. Although declining tendencies were observed in some countries already in the nineteenth and early twentieth century, there were also periods of stagnation and increase. For old persons, the remaining expectation of life did not increase substantially and their numbers grew only slowly as more people survived to retirement age.
In the last two or three decades a new factor has come into play: an unprecedented decline in age-specific mortality of the oldest-old themselves which has caused the life expectancy at ages 80, 90, even 100, to increase. Even though the reductions in mortality have at these ages usually been smaller than below age 80, the cumulative effect of the change has been to increase the numbers of the very oldest most rapidly in relative terms. In low-mortality countries the oldest-old are now the most rapidly growing segment of the population and, among them, it is the number of centenarians that is growing at the fastest pace.
Aggregated data for twelve countries with the most accurate information in Table 2 show that during the last 40 years the number of octogenarians has grown 4-fold, that of nonagenarians 8-fold and that of centenarians more than 20-fold. At each age the growth has been larger among females than males and the sex ratio has become increasingly lopsided, women outnumbering men 2:1 and among centenarians 5:1.
If we look at the oldest-old as a single group, more countries can be brought into comparison because uncertainty about centenarians in them hardly affects the figures. Table 3 gives the 40-year growth factor in 26 countries. In most of them the growth factor falls into the narrow range between 2.5 and 3.5. As the data for Canada and Ireland are not very trustworthy, this leaves only three countries clearly outside the range: Japan in a class of its own with an explosive 8-fold increase, trailed in some distance by Finland and Switzerland. All three are countries where the older age groups were until recently quite small. At the opposite end we find such countries of traditionally great longevity as Iceland, the Netherlands and Norway where, not surprisingly, the additional growth in numbers has been more moderate in relative terms. East Germany ranks low because of slow progress in survival.
The number of women, already larger than that of men to begin with, has continued to grow at a faster speed. There are only three exceptions to this: Japan which presents characteristics of its own, and Spain and Portugal where the 1950 data were not very reliable.
The momentum of change makes it likely that the old age populations in lowmortality countries will continue to grow rapidly and even at increasing speed.
Updated by V. Castanova, 1 March 1999