The Demography of Centenarians in England and Wales - article ; n°1 ; vol.13, pg 139-156

R. Thatcher

Description

Population - Année 2001 - Volume 13 - Numéro 1 - Pages 139-156
Thatcher Roger.-The Demography of Centenarians in England and Wales Using a new database, the article investigates the causes of the current explosion in the numbers of centenarians. It then examines the latest official projections for the future and their implications for the highest ages which are likely to be attained.
18 pages
Source : Persée ; Ministère de la jeunesse, de l’éducation nationale et de la recherche, Direction de l’enseignement supérieur, Sous-direction des bibliothèques et de la documentation.

Sujets

• Sociologie, société et politique

Informations

• Publié par: POPULATION0
• Publié le: 01 janvier 2001
• Nombre de lectures: 15
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

R. Thatcher
The Demography of Centenarians in England and Wales
In: Population, 13e année, n°1, 2001 pp. 139-156.
Abstract
Thatcher Roger.-The Demography of Centenarians in England and Wales Using a new database, the article investigates the
causes of the current "explosion" in the numbers of centenarians. It then examines the latest official projections for the future and
their implications for the highest ages which are likely to be attained.
Citer ce document / Cite this document :
Thatcher R. The Demography of Centenarians in England and Wales. In: Population, 13e année, n°1, 2001 pp. 139-156.
http://www.persee.fr/web/revues/home/prescript/article/pop_0032-4663_2001_hos_13_1_7234The Demography of Centenarians
in England and Wales
Roger Thatcher*
During the 1940s and 1950s a new demographic trend made its
appearance: death rates at very high ages (80 and over) started to fall
throughout the developed world. However, this was not at all obvious at
the time. In individual countries, the initial changes were small in compar
ison with normal fluctuations and there were often doubts about the relia
bility of the data. Also, changes at these very high ages attracted less
attention than the important changes which were taking place at lower
ages.
As time went by, the new trend at the very high ages became firmly
established and started to produce some noticeable effects. These included
a spectacular percentage rate of increase in the numbers of centenarians.
Also, it became clear that record ages, which many experts had previously
regarded as the highest ages which it was possible for members of the
human species to reach (first 112 years, then 115 years), were being
broken.
In 1990 the Cambridge Group for the History of Population and
Social Structure invited three interested researchers to collaborate infor
mally in a project on the maximal length of life. They soon decided that a
proper investigation would call for the examination of reliable data from
as many countries as possible. Between them, and with funding from the
Danish Research Councils and the U.S. National Institute of Aging, they
assembled and computerised all the published official statistics on deaths
at ages 80 and over in 30 countries since 1960, or earlier in many cases.
However, only 13 countries (which included England and Wales) had data
which were sufficiently extensive and reliable for detailed analysis. This
database on old age mortality has been used to produce most of the figures
and tables in this article. The full database is currently held at the Max
Planck Institute for Demographic Research in Rostock, Germany, where it
* Formerly Registrar General and Director of the Office of Population Censuses and
Surveys.
Population: An English Selection, 13 (1), 2001, 139-156 140 R. Thatcher
is identified for reference as the Kannisto-Thatcher (K-T) database.
Copies can be obtained by institutions and serious research workers on ap
plication.
An important feature of the new database is the method which is
used to construct estimates of the past population numbers at very high
ages. In countries which do not have registers, it is common to
find that many of the very high ages recorded in censuses are erroneous
and less accurate than the ages which are recorded in death registrations.
However, it is not necessary to use the censuses. Once all the members of
a given birth cohort have died, the dates of birth and death which are
recorded in their death registrations give enough information to recons
truct the numbers who were alive at each date in the past, at least at ages
where international migration can be ignored. By this method, known as
the method of "extinct generations" or "extinct cohorts," improved est
imates of past population numbers can be made retrospectively. Extensions
of the method can also be used to produce provisional estimates for
cohorts which are not yet fully extinct. These methods have been applied
to all the countries in the database.
In the case of England and Wales annual series were produced from
1911 to 1996, though the later figures are still provisional. As the volume
of data is large, the method of presentation in this article is mainly graphic
al, but the numerical data for selected dates are given in Appendix I.
In England and Wales there are also other estimates of the numbers
of centenarians, based on the censuses and on samples of national insu
rance pensioners. These alternative estimates are discussed in Appendix II.
The "Explosion" of Centenarians
Figure 1 shows the estimated numbers of centenarians (aged 100 and
over) from 1911 to 1996. Females now outnumber the males by more than
eight to one.
From 1911 until the late 1940s the number of centenarians was tiny,
only one or two hundred. They were very rare and were more objects of
curiosity than anything else. Then, from about 1950, the numbers started
to rise and by 1996 had already reached nearly 6,000. The are
still fairly small but the rate of increase has been very large, about 7% per
annum, roughly doubling every 10 years. No other demographic group has
"explosion." increased at anything Although like these this figures rate, are which for has England been and fairly Wales described they are as tyan
pical. The same thing has been happening in all the other industrialised
countries for which there are reliable data.
There are several causes which have contributed to this "explosion":
increased numbers of births in the 19th century, improved survival from
birth to age 80, and then the new demographic trend in death rates at very I
Demography of Centenarians in England and Wales 141 The
Population Ined 363 00 6,000 I III
5,000
Total // — 4,000
- 3,000 // -
//Females
— 2,000
- 1,000
n
1911 1921 1931 1941 1951 1971
Year
Figure 1 .- Population aged 100 years and over on 1st January
England and Wales
high ages. We shall examine and quantify these in turn. For this purpose
we shall need to bring together data from several different sources: the Off
ice for National Statistics (ONS) statistics for births, the Government Ac
tuary's Department (GAD) unpublished cohort life tables for survival from
birth to age 80, and the K-T database for survival above age 80. It will be
convenient to compare the cohort born in 1850 (which produced the per
sons who were aged 100 on 1 January 1951) with the cohort born in 1895
(which produced the persons who were aged 100 on 1 January 1996).
Births
The effect of births is easy to quantify. Between 1850 and 1895 the
number of births increased by 55% for males and by 56% for females. A
century later, these extra births will have increased the numbers of those
aged 100 by factors of 1.55 for males and 1.56 for females.
Survival From Birth to Age 80
There was a very considerable increase in the proportion who survi
ved from birth to age 80. This finding is illustrated in Figure 2, which is 142 R. Thatcher
derived from unpublished GAD cohort life tables. The horizontal scale
shows both the year of birth for each cohort and the year when it reached
age 80. For example, the first points on the left show that 7% of the males
and 11% of the females born in 1841 survived to reach age 80 in 1921. By
the end of the period, the survival rate had greatly improved. Of course,
the reasons are well known: better hygiene and sanitation, and improved
food, housing, living standards and medical treatment.
Survival, per cent
Born 1841 1851 1861 1871 1881 1891 1901 1911 1921
Reach 80 1921 1931 1941 1951 1961 1971 1981 1991 2001
Figure 2.- Survival from birth to age 80
England and Wales, based on civilian deaths
A striking feature of Figure 2 is the widening of the gap between the
lines for males and females in the cohorts born between 1871 and 1901.
Some epidemiologists have suggested a possible reason. These cohorts i
nclude the men who served in the First World War, when many servicemen
took up smoking. The life tables do not include war deaths, but many se
rvicemen who survived the war would have died of lung cancer later,
before reaching age 80. This factor would have contributed to the wide
ning of the gap. Another factor would have been the reduction in women's
deaths associated with childbirth.
The combined effect of these changes between the two cohorts born
in 1850 and 1895 was to increase the survival rate from birth to age 80 The Demography of Centenarians in England and Wales 143
from 8.46% to 15.76% (by a factor of 1.8( for males, and from 13.38% to
30.78% (by a factor of 2.30) for females.
Death Rates at Age 80
Figure 3 shows the death rates at age 80 from 1911 until 1995, for
males and females. Until at least the 1940s, the death rates at age 80 were
very high and had been high for a long time. People thought that not much
could be done about deaths at such a high age and indeed there were many
diseases for which people over 80 could not be treated, or it was not wor
thwhile to treat them. Then from about the 1940s or 1950s the death rates
at age 80 started to fall at a speed which shows up quite noticeably in the