From the Departments of Medicine (A.M.E., P.F.) and Community Medicine,
Division of Epidemiology (M.G., L.J.), Lund University, University Hospital,
Malmö, Sweden.
Correspondence to Dr Ali M. Elneihoum, Department of Medicine, University of Lund, University Hospital, S-205 02 Malmö, Sweden.
Methods—The series comprised 2290 patients, 1051 men and 1239
women, followed up for 3 years after their first stroke during the
period 1989 through 1992.
Results—Of the series as a whole, 959(43.4%) died and 137(6%)
suffered a second nonfatal stroke. Multivariate
analysis showed age, type of stroke, severity of stroke, and
the presence of diabetes mellitus or cardiac disease each to be an
independent predictor of mortality, and the presence of diabetes,
atrial fibrillation, and history of transient ischemic attacks
each to be associated with increased risk of recurrence.
Treatment for hypertension was associated with a protective effect. As
compared to those with first stroke in 1989, those with first stroke in
1992 were characterized by a lower recurrence rate, which was
reduced by 70% in the male subgroup (P=0.003) and by
80% in the female subgroup (P=0.006), the corresponding
reduction in all-cause mortality being 30% (P=0.007)
and 10% (P=0.5, NS). Recurrence-free survival
rates differed markedly between the 17 residential areas studied.
Conclusions—The present study showed that survival rates
after stroke have improved and recurrence rates have declined
in this urban population. Further studies are needed to ascertain to
what extent intraurban variation in the proportion of
recurrence-free 3-year survivors is to be explained by
differences in the severity of initial stroke and other prognostic
markers, or in initial treatment and secondary preventive measures.
The beneficial effects of secondary preventive measures after stroke,
such as antihypertensive, antiplatelet, or anticoagulant therapy
and surgical treatment of severe symptomatic carotid artery
stenosis, have been well established in clinical
trials.4 5 6 7 8 9 However, little evidence is available
as to whether the long-term survival rate after stroke has
improved.
All patients residing in the city of Malmö who had their
first-ever stroke after January 1, 1989, are registered in the
Malmö Stroke Registry (STROMA), which was established in
1989.
The approximately 250 000 residents of the city live in 18
administrative areas, which differ widely from each other in
sociodemographic, morbidity, and mortality profiles.
Data from this registry have been used to study survival and
recurrence rate in relation to residential area and factors
known to be associated with stroke outcome and to determine whether
cases occurring during the 4-year period 1989–1992 were characterized
by any change in 3-year survival or recurrence rates.
The present study series comprised 2290 patients, 1051 men and 1239
women, who had their first stroke during the 4-year period
1989–1992.
Prognostic Markers
Stroke Severity
Residential Area
Follow-Up
Statistical Analysis
In terms of stroke types, 68 (2.7%) of the 2495 stroke events were due
to subarachnoid hemorrhage and 240 (9.6%) to
intracerebral hemorrhage, 1388 (55.6%) as
ischemic stroke and 799 (32%) as unspecified stroke. In terms
of severity, which was assessed in about 70% of cases, 594 cases were
classified as minor stroke (Katz Index grades A to B), 302 cases as
moderate stroke (Katz grades C to E), and 689 cases as major stroke
(Katz grades F to G).
Survival and Recurrence Rates
Outcome Predictors
Diabetes mellitus, atrial fibrillation and a history of transient
ischemic attack were each found to be a significant independent
predictor of recurrent stroke (Table 1
Prognosis in Relation to Residential Area
Time Trends
Compared to those with first stroke in 1989, those with first stroke in
1992 were characterized by a lower recurrence rate, which was
reduced by 70% in the male subgroup (P=0.003) and by 80%
in the female subgroup (P=0.006), the corresponding
reduction in all-cause mortality being 30% (P=0.007) and
10% (P=0.5, NS) (Table 2
Although the improved survival rate in Malmö is
consistent with the previously reported decrease in the
immediate mortality rate, the declining recurrence independent
of other risk factors suggests that the improved quality of secondary
preventive measures may have contributed to the improved outcome. The
smaller decline in the mortality rate among women may simply reflect
the higher mean age of that subgroup compared with that of the men (78
versus 72 years).
Although it is well known that prognosis after stroke (in terms of both
recurrence and survival) is related to a number of risk
factors; prognosis in relation to place of residence has been
investigated in few studies. In previous studies at
Malmö,14 15 both incidence and mortality
pattern of different diseases were shown to differ widely among the 17
residential areas, with the variation being related to a number of
sociodemographic factors. The intraurban variation with regard to
stroke-free survival found in the present study is
consistent with these previous findings. Treatment after stroke
is generally the responsibility of the primary health care physicians
in the city. To what extent differences in stroke-free survival reflect
differences regarding initial treatment and secondary prevention
remains to be evaluated. In the analysis, we have
with exception for age made no adjustment for the possibility that
stroke victims from different areas of living may differ with regard to
the exposure to risk factors related to survival and
recurrence.
Questions may be raised regarding the validity of the estimates of
recurrence and survival rates. Diagnosis of stroke was based on
established clinical criteria and findings of CT and MRI. Malmö
University Hospital is the only hospital for somatic disorders in the
city, and all stroke patients are therefore referred to this hospital
for evaluation. This includes patients belonging to the catchment area
but initially admitted to a hospital outside the city. Although the
annual outmigration rate from Malmö is about 1%, owing to
computerized access to the national cause-of-death registry it is
nonetheless possible to obtain complete follow-up data.
The relatively high percentage of cases (32%) in which the cause of
stroke remained unclear merits comment. Most of these patients were
elderly (mean±SD age, 82±9 years), many with very severe stroke. On
clinical grounds it was felt that treatment was unlikely to be altered
by access to more detailed knowledge of the underlying cause(s).
In summary, the present study showed survival rates following
stroke to have improved and recurrence rates to have declined
in this urban population. Further studies are needed to ascertain to
what extent intraurban variation in the proportion of
recurrence-free 3-year survivors is to be explained by
differences in the severity of initial stroke and other prognostic
markers or in initial treatment and secondary preventive measures.
Received May 5, 1998;
revision received July 22, 1998;
accepted July 22, 1998.
2.
Peltonen M, Asplund K. Age-period-cohort effect on
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American Ticlopidine Study (CATS) in thromboembolic stroke.
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ischemic attack or minor stroke. Lancet. 1993;324:1255–1262.
7.
Lindblad U, Rastam L, Ranstam J. Stroke morbidity in
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A, Riekkinen PJ. The European Stroke Prevention Study: results
according to sex. Neurology. 1991;41:1189–1192.
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© 1998 American Heart Association, Inc.
Original Contributions
Three-Year Survival and Recurrence After Stroke in Malmö, Sweden
An Analysis of Stroke Registry Data
Abstract
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
Background and Purpose—Data from
the Malmö Stroke Registry were analyzed to determine
whether any change in survival or nonfatal stroke recurrence
rates had occurred during the 4-year period from 1989 through 1992 and
whether prognosis was related to area of residence.
Key Words: epidemiology • mortality • recurrence • stroke
Introduction
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
According to official statistics, the age-adjusted stroke
mortality rate in Sweden has declined from approximately 9/10 000 to
7/10 000 during the 14-year period from 1980 through
1994.1 Findings in follow-up studies at some
hospitals have suggested that this decline may be partly attributable
to improvement in the acute survival rate.2 3
Subjects and Methods
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
Stroke was defined as rapidly developing clinical signs of local
or global loss of cerebral function lasting for >24 hours (or leading
to death before then) with no apparent cause other than cerebral
ischemia or hemorrhage.10 By
definition, cases of transient ischemic attack were excluded.
Only patients with first-ever stroke after January 1, 1989, were
included in STROMA. All recurrences were recorded, provided
that the recurrent event occurred at least 4 weeks after the preceding
event. Details of case retrieval and ascertainment have been reported
previously.11
Cardiovascular Risk Factors
Mortality and recurrence rates were studied in relation
to the following prognostic markers: treatment for hypertension prior
to stroke or within the first week after admission; the presence of
diabetes mellitus (ie, previously diagnosed or repeat fasting blood
glucose values of 
6.5 mmol/L). The subgroup with cardiac disease
included patients with ischemic heart disease, valvular
heart disease, and heart failure. Patients with at least one prior
serum total cholesterol value of 6.5 mmol/L were
considered to have hypercholesterolemia.
Smokers were defined as those smoking regularly at the onset of stroke
and ex-smokers as those who had quit smoking at least 1 year before
their stroke.
Stroke severity assessment, based on the Katz
index,12 was performed for approximately 70% of
patients by experienced occupational therapists.
The city of Malmö comprises 18 administrative areas, one
of which (the harbor area) was not included in the analysis
owing to its very small population.
Survival and recurrent stroke data for the 3-year period
after first stroke were obtained from the stroke registry for all 2495
patients, with each patient being followed up until second stroke,
death, or the end of the 3-year follow-up period. Those who died were
traced in the cause-of-death register, in which cause of death is
classified according to the International Classification of
Diseases, 9th Revision (ICD-9) codes.
The Kaplan-Meier method was used to estimate the probability of
survival and the Cox proportional hazards model to test the risk
factors studied as independent determinants of survival and
recurrence rates. Age adjustment was done with the direct
method, using the entire population of Malmö as the standard
population, with age distribution being averaged for the 4-year period
1989-1992. All statistical calculations were performed by computer,
using SPSS software (Statistical Package for the Social Sciences; SPSS
Inc). P values of <0.05 were considered statistically
significant.
Results
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
The series as a whole (n=2290)-1051 men (mean±SD age, 72±12
years) and 1239 women (mean±SD age, 78±11 years)-account for a total
of 2495 stroke events during the 4-year period 1989–1992. In the city
of Malmö, the annual stroke incidence per 100 000 was 300 in
1989, 270 in 1990, 284 in 1991, and 286 in 1992.
Of the series as a whole (n=2290), 959 (43.4%) died within 3
years and 137 (6%) had a new nonfatal stroke during the 3-year
follow-up period. Three years after the first stroke event, 1158
(50.6%) of the patients were still alive, and had not had a second
stroke (Figure 1
and 2).
View larger version (12K):
[in a new window]
Figure 1. Accumulated survival rate after stroke in
different age groups. The light solid line indicates the age group <60
years; the long dashed line, 60 to 69 years; the short dashed line, 70
to 79 years; and the heavy solid line, >80 years.
View larger version (14K):
[in a new window]
Figure 2. Accumulated rate of recurrent nonfatal stroke in
different age groups. The light solid line indicates the age group <60
years; the long dashed line, 60 to 69 years; the short dashed line, 70
to 79 years; and the heavy solid line, >80 years.
Age, the presence of diabetes mellitus or cardiac disease,
severity of the stroke (Katz Index grade), and type of stroke were each
found to be a significant independent predictor of mortality after
stroke. Treatment for hypertension and
hypercholesterolemia were each associated with
an improved survival rate (Table 1).
View this table:
[in a new window]
Table 1. Influences of Different Prognostic Markers on
All-Causes Mortality and Incidence of Nonfatal Recurrent
Stroke 
).
The 17 residential area subgroups differed substantially
with regard to the proportion of survivors who had not experienced a
second stroke during the 3-year follow-up. The age-adjusted survival
rates for the 17 residential areas are shown in Figure 3.
View larger version (83K):
[in a new window]
Figure 3. Age-standardized recurrence-free survival
rates in relation to the area of residence in the city of Malmö.
The white areas are those with average rates (median, 0.51;
minimum-maximum, 0.49-0.54); light gray, areas with rates below city
average (median, 0.45; minimum-maximum, 0.36-0.47); and dark gray,
areas with rates above city average (median, 0.58; minimum-maximum,
0.56-0.64).
There was a trend toward improving prognosis after stroke with
calendar time during the 4-year study period independent of other
prognostic factors. ).
View this table:
[in a new window]
Table 2. Incidence and Relative Risk of Nonfatal Recurrent
Stroke and All-Causes Mortality in Relation to Year of First
Stroke
Discussion
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
According to official statistics, there has been a continuous
decline in age-adjusted stroke mortality in Sweden since
1980,1 a trend manifested in both the male and
female subgroups. Findings in previous studies3
at some Swedish hospitals suggest that the decline has been caused in
part by a decrease in immediate mortality. Evidence is also
available3 13 which suggests that the same period
has been characterized by a shift toward less severe stroke, with no
concomitant decline in stroke incidence.
Acknowledgments
This study was supported by a grant from Vårdal-stifelsen. We
would like to thank Ingela Jentorp, RN, for her meticulous stroke
registration.
References
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
1.
Causes of Death, 1994. The National
Board of Health and Welfare, Centre for
Epidemiology. Official Statistics of Sweden;
1996. ISBN 91-7201-080-0: ISSN 1401-0224.
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