Mortality from amyotrophic lateral sclerosis in ... - ResearchGate

Acta Neurol Scand 2001: 104: 232–235
Printed in UK. All rights reserved
Copyright # Munksgaard 2001
ACTA NEUROLOGICA
SCANDINAVICA
ISSN 0001-6314
Mortality from amyotrophic lateral sclerosis
in Finland, 1986–1995
Maasilta P, Jokelainen M, Löytönen M, Sabel CE, Gatrell AC.
Mortality from amyotrophic lateral sclerosis in Finland, 1986–1995.
Acta Neurol Scand 2001: 104: 232–235. # Munksgaard 2001.
Objective – To study the possible changes, between 1986 and 1995, in
the mortality due to amyotrophic lateral sclerosis (ALS) among
Finnish patients. Materials and methods – A total of 1000 deaths from
ALS were extracted from the Finnish Death Certificate Register for
the study years. General population data were obtained from the
Statistical Yearbooks of Finland. Results – From a death rate of 1.54/
100,000 in 1986 an increase to 2.27/100,000 in 1995 was observed.
Since 1963 the number of ALS deaths has tripled. The documented
increased life-expectancy in Finland correlates with the ALS death
rate, at least partly explaining the increase. Contrary to other
countries, on the whole equal numbers of men and women died of
ALS. Women tended to be older than men when they died of ALS.
Conclusion – In accordance with other countries ALS mortality in
Finland is steadily increasing.
P. Maasilta 1 , M. Jokelainen 2 ,
M. Löytönen 3 , C. E. Sabel 4 ,
A. C. Gatrell 5
1 Department of Pulmonary Medicine, Helsinki
University Central Hospital, Helsinki, Finland;
2 Harjukatu 40 C 3, Lahti, Finland; 3 Department of
Geography, University of Helsinki, Helsinki, Finland;
4 School of Geography & Geosciences, University of St
Andrews, St Andrews, United Kingdom; 5 Institute for
Health Research, Lancaster University, Lancaster,
United Kingdom
Key words: amyotrophic lateral sclerosis; mortality;
Finland
P. Maasilta, Department of Pulmonary Medicine,
Helsinki University Central Hospital, P.O. Box 340,
FIN-00029 HUS, Finland
Tel.: +358 9 471 60083
Fax: +358 9 471 74020
e-mail: paula.maasilta@helsinki.fi
Accepted for publication April 17, 2001
The occurrence of amyotrophic lateral sclerosis
(ALS), the main variant of motor neurone disease
(MND), has for years been followed in many
countries (1, 2). ALS patient data have been
collected from records kept by primary care
physicians, neurologists and hospital discharge
registers. Health insurance records and mortality
statistics have also been utilized.
Descriptive epidemiological studies have
revealed the magnitude of the burden which this
disease constitutes to both health care and human
resources. Analytic epidemiological studies (3, 4)
have shed some light upon the possible aetiological
risk factors. Despite extensive research on
the subject, the aetiology and pathogenesis of this
devastating disease are still unclear, posing a
challenge to the research community (5).
The epidemiology of ALS in Finland has been
studied since 1975 (6) by utilizing various data
sources including the Death Certificate Register.
The latest mortality study covering the years
1963–1982 was published in 1987 (7). ALS
mortality in Finland has been constantly increasing,
mirroring the situation in several other
European countries such as Sweden (8, 9),
Norway (10), England (4), and Italy (11).
Mortality statistics in MND may be sufficient
for studying trends with time (3), and possibly
variation in place, but are likely to underestimate
rates in the elderly, particularly in medically
deprived areas, where age-specific rates may be
higher than reported.
In 2000, a novel approach to the epidemiology
of ALS was introduced by a British–Finnish
research team by using time geography as the
conceptual framework. Utilizing data from the
Finnish Death Certificates Registry this team
adapted a geographical information system
(GIS)-based approach where spatial and temporal
patterns were revealed using a spatial estimation
technique known as kernel estimation (12). The
present study was designed to examine the
232

ALS mortality in Finland 1986–1995
possible changes in the mortality of Finnish ALS
patients by analysing the mortality trend from
1986–1995.
Material and methods
A total of 1000 deaths from ALS were recovered
from the digitally recorded Finnish Death
Certificate Register covering years 1986–1995.
All data were obtained from individual-level
register-based computerized databases. The
yearly data comprised sex, date and place of
birth, and date of death (12). All ALS patients
included in this study were born in Finland. Since
1976 all hospital districts in Finland have had a
Neurology department run by specialists, who
make all ALS diagnoses.
The ALS mortality data from 1963 to 1982 was
obtained from one of the authors (M.J.).
Data on the general population were obtained
from the Statistical Yearbook of Finland (13).
Spearman’s correlation was used for correlation
analysis. All computations were performed using
a commercial statistical package (Statistica 2 v. 5,
StatSoft Inc., Tulsa, OK, USA).
Results
The population of Finland was 4,539,500 in 1963,
4,910,664 in 1986, and by 1995 had increased to
5,116,826. The number of ALS deaths increased
steadily during the period from 1963 to 1995. In
1963 40 people died of ALS and in 1995 116
people. Also the ALS death rate/100,000 has
steadily increased from 0.85 in 1963 and 1.54 in
1986 to 2.27 in 1995 (r=0.912, P

Maasilta et al.
Fig. 4. The mean age and standard deviation at death from
amyotrophic lateral sclerosis in men and women in Finland
from 1986 to 1995.
Discussion
In accordance with data from other countries (4,
8–11) and previous data from Finland (7) this
study shows a substantial increase in ALS
mortality. Also the annual death rate is on the
increase without any cyclic or other variation. In
less than 25 years since 1963 the number of ALS
deaths has tripled, while the population has
increased only by 11.3%.
Most of the ALS deaths occurred in the over-55
population. Previously in Finland the mean age at
death from ALS had increased from 62 in 1963 to
66 in 1982 with no change in the mean duration
of disease (7). We found the mean age at death to
be 66.5 in 1995. There has been no major change
in the treatment of this disease in Finland during
the study years, but the life-expectancy of the
population in general has increased throughout
the years. Similar to our findings a maximal
incidence rate of between 61 and 65 years, with a
median survival of 28 months has been reported
from Norway during the time-period from 1978 to
1988 (10).
Most studies report a higher incidence of ALS
in men compared to women of 1:1.5 to 2:1 (10,
15). Although the forms of ALS have been
reported to vary in men and women (15) there
are no data indicating a gender difference in
survival. In an earlier study from Finland the
mortality men:women ratio was 0.94 to 1 (14).
Our finding is similar to that. With a large yearly
fluctuation roughly the same number of men and
women died of ALS. Again no cyclic or other
pattern was seen. In general women live noticeably
longer than men in Finland (13). The shorter
life-expectancy of men could be one of the factors
explaining the equal gender ratio in the ALS
death rate in Finland. We also analysed the
potential effect of the second world war as
regards the gender ratio. No identifiable effect
Fig. 5. Scatter plot showing the annual deathrate from amyotrophic
lateral sclerosis versus the life-expectancy in Finland
from 1963 to 1995.
could be found; the annual rate of the ALS cases
is so small that it accommodates for the slightly
higher overall mortality of men caused by the
war.
We showed that the increasing life-expectancy
of the population in Finland correlates with the
ALS death rate. Thus the increased age of the
population at least partly explains the increased
death rate of ALS. A study from Sweden with a
similar health care system and comparable
homogenous population characteristics to
Finland showed that a subpopulation susceptible
to MND exists there (9). The increased life
expectancy of the population in Sweden has
resulted in more people living to the ages, when
MND is expressed (9). Although our study was
not designed to look at the roles of increased
population life expectancy and environmental
factors respectively, it is likely that the situation
in Finland would be identical to that in Sweden.
We undertook a retrospective study based on
death certificates. However, the possible sources
of errors in our study are insignificant. The
sample comprises all ALS deaths from 10 years
and is large enough to control for random
fluctuation. Also, all ALS diagnoses are made
by neurologists in Finland, which makes diagnostic
errors unlikely.
Acknowledgements
The study has been funded by the Helsinki University Central
Hospital Special Funds.
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