Prevalence of Stroke and Its Risk Factors in
Urban Sri Lanka
Population-Based Study
Thashi Chang, MD, DPhil; Seneth Gajasinghe, MBBS; Carukshi Arambepola, MD
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Background and Purpose—Stroke is a leading cause of disability and death worldwide. In the absence of published
population-based prevalence data, we investigated the prevalence and risk factors of stroke in a population of varying
urbanization in Sri Lanka.
Methods—A population-based, cross-sectional study was conducted among 2313 adults aged ≥18 years residing in
Colombo, selected using a multistage, probability proportionate-to-size, cluster sampling technique. Data were collected
using an interviewer-administered questionnaire. Ever diagnosis of stroke was confirmed by medical doctors based on
World Health Organization criteria and corroborated by documental evidence.
Results—Of the total population (52.4% women; mean age, 44.2 years; SD, 16.6), the prevalence of stroke was 10.4 per 1000
(95% confidence interval, 6.3–14.5) with a 2:1 male:female ratio. Beyond the age of 65 years, the prevalence was higher
by 6-fold among men and by 2-fold among women. Ninety two percent had developed hemiparesis, 58.3% had dysphasia,
and 16.7% had loss of balance. Hypertension was the commonest risk factor (62.5%) followed by smoking (45.8%),
excess alcohol (41.7%), diabetes mellitus (33.3%), and transient ischemic attack (29.2%); 79.2%, predominantly men,
had ≥2 risk factors. A percentage of 58.3 had brain computed tomographic scans, of whom 85.7% had ischemic strokes.
A percentage of 64.3 had to change or give up working because of stroke-related disability.
Conclusions—Age-adjusted stroke prevalence in urban Sri Lanka lies between high-income and low-/middle-income
countries. The prevalence of stroke and its risk factors were higher among men. (Stroke. 2015;46:2965-2968. DOI:
10.1161/STROKEAHA.115.010203.)
Key Words: prevalence ◼ risk factors ◼ Sri Lanka ◼ stroke
S
troke has been ranked the second most common cause
of death and the third most common cause of disabilityadjusted life years lost worldwide.1 Overall, 71% of these
stroke deaths and 78% of disability-adjusted life years lost
occur in low- and middle-income countries.1 The South Asian
region makes up >40% of the developing world and is thought
to be the highest contributor to the global stroke mortality.2
However, apart for a few studies conducted in India, welldesigned population-based stroke prevalence data from the
South Asian region are scarce.2 Given the differences in population structures, level of education, cultural belief-based practices, and access to and availability of stroke-related health
services between countries, data from one country are unlikely
to accurately reflect the stroke prevalence in the region or
that of another country in the same region. Population-based
stroke epidemiology data are essential to develop effective
stroke prevention, management, and rehabilitation strategies
specific to each country and its population, as well as to plan
effective global campaigns against stroke.
The burden of stroke in Sri Lanka is on the increase
with the current demographic transition toward an ageing
population. However, population-based stroke prevalence
data are limited to a single unpublished study done in a
suburban community before 2003.3 We aimed to determine
the prevalence of stroke and its risk factors in an urban
setting in Sri Lanka, which represents varying degrees of
urbanization.
Methods
A population-based cross-sectional study was conducted in the district of Colombo, which is one of the 25 administrative divisions of
Sri Lanka comprising 2.3 million inhabitants of diverse socioeconomic, ethnic, and religious backgrounds and has the highest population density of 3300/km2. It includes the commercial capital of Sri
Lanka that represents the most urban district in the country. Colombo
is divided into 566 Grama Niladhari (GN) divisions, which are the
smallest administrative units in a district. The GN divisions under the
purview of Municipal or Urban Councils comprise the urban sector,
whereas all other GN divisions comprise the suburban sector.4
Received May 27, 2015; final revision received August 6, 2015; accepted August 7, 2015.
From the Department of Clinical Medicine (T.C., S.G.), Department of Community Medicine (C.A.), and Faculty of Medicine (T.C., S.G., C.A.),
University of Colombo, Colombo, Sri Lanka.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.115.​
010203/-/DC1.
Correspondence to Thashi Chang, MD, DPhil, Department of Clinical Medicine, University of Colombo, 25, Kynsey Rd, Colombo 08, Sri Lanka. E-mail
[email protected]
© 2015 American Heart Association, Inc.
Stroke is available at http://stroke.ahajournals.org
DOI: 10.1161/STROKEAHA.115.010203
2965
2966 Stroke October 2015
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The study population included adults aged ≥18 years residing for
>1 year in the district of Colombo. The sample size was determined
as 2387 to detect an expected prevalence of stroke of 0.9% with 0.01
precision, 5% level of significance, design effect of 6 for a cluster
size of 51 and ρ of 0.1, and 15% nonresponse. The study sample
was selected using a multistage sampling technique from 46 GN divisions to obtain a cluster size of 51. In the first stage, the number of
GN divisions to be selected from either the urban or suburban sector
was determined proportionate to the population in each sector. Within
each sector, the required number of GN divisions was selected using
probability proportionate-to-size technique. In subsequent stages, 17
households (assuming 3 adults in each household) were selected as
a cluster in each selected GN division. The first household in each
cluster was selected randomly, whereas the others were taken consecutively from the first selected household. Data were collected over
a period of 11 months.
A pretested, validated questionnaire (online-only Data
Supplement) with both open- and close-ended questions in the local vernacular language (Sinhala and Tamil) was administered to the
participants by trained preintern medical officers. We used the World
Health Organization definition of stroke.5 Where available, data were
corroborated by documental evidence (medical records, brain scan
reports, and medication history) in addition to interviewing the participants and their carers.
Results
A total of 2313 people of 782 households were recruited for
this study, giving a response rate of 96.9%. Of them, 52.4%
were women. The mean age of participants was 44.2 years
(SD, 16.6 years) with a median age of 42 years. They represented the adult population in Sri Lanka, with the majority
in the age group of 18 to 44 years and only 12.8% in the age
group of ≥65 years.
Age and sex-specific prevalence of stroke is shown in
Figure. In the study population, 24 were identified with an
ever diagnosis of stroke, giving a crude stroke prevalence of
10.4 per 1000 adults (95% confidence interval [CI], 6.3–14.5
per 1000). It further showed a 2:1 ratio between men (15 per
1000 men; 95% CI, 7.8–22.2) and women (7 per 1000 women;
95% CI, 2.3–11.7). Among men, the highest prevalence was
Figure. Age- and sex-specific prevalence of stroke among adults
aged ≥18 years in the district of Colombo (prevalence of stroke
among adults aged 18 to 44 years was zero and is not shown
in the figure; 95% confidence intervals are indicated within
parentheses).
in the age group of 65 to 74 years, whereas among women,
the highest prevalence was in the age group of 75+ years.
Compared with the least-risk group (18–44 years), the prevalence was 6-fold higher among men (62 per 1000 men; 95%
CI, 20–104) and 2-fold higher among women (18 per 1000
women; 95% CI, 2–38) in the age group of >65 years.
The mean age of stroke victims at the onset of stroke was
58.2 years (SD, 12.2 years). The demographic characteristics,
clinical presentations, and stroke risk factors in patients at the
time of ever diagnosis of stroke are shown in Table.
Hemiparesis and difficulty of speech were the commonest
presenting symptoms, whereas hypertension was the commonest risk factor. A percentage of 79.2, mostly men, had ≥2 risk
factors. None of the women smoked tobacco or consumed alcohol. A significant difference was noted between men and women
for the presence of ≥2 risk factors and specifically for smoking,
alcohol, and past stroke/transient ischemic attack (P<0.01).
Of all stroke victims, 58% had cranial computed tomographic scans, of which 85.7% were confirmed as ischemic
and the rest as hemorrhagic.
The monthly income was <Rs. 10 000 (USD 75) in 71%
of the stroke victims. Of those who were employed at the
time of stroke, 64.3% had to either give up or change their
occupation because of stroke-related disability. Some left the
job because of their physical disabilities, whereas some were
asked to leave.
Discussion
In this population-based study conducted in the most populace district in Sri Lanka, the prevalence of stroke was 10.4
per 1000 adults aged ≥18 years (95% CI, 6.3–14.5) with a
2:1 male:female ratio. When age adjusted, the prevalence of
stroke in inhabitants aged ≥65 years was higher (37 per 1000
adults; 95% CI, 15.5–58.5) than that reported for rural and
urban India and rural China but lower than that reported for
urban China.10
Age remains the strongest nonmodifiable risk factor of
stroke. All the stroke victims in our study were >45 years old,
whereas the prevalence of stroke increased 6-fold among men
and 2-fold among women aged >65 years. The mean age of
stroke onset was marginally lower than that of regional countries (59 years in Pakistan; 63 years in India) and markedly
lower than that of Western countries (68 years in the United
States; 71 years in Italy).2 This disparity between the South
Asian countries and Western countries probably reflects the
differences in the prevalence of stroke risk factors and the
access to healthcare.
One third of stroke victims reported a previous history of
transient ischemic attack or stroke, whereas 84.2% had ≥2 risk
factors. As expected, the prevalence of vascular risk factors
among the stroke victims was higher than that of the general
population (Table). Rapid urbanization leading to sedentary
lifestyles is likely to increase the prevalence of conventional
stroke risk factors. The magnitude of the effect of nonconventional stroke risk factors, such as central nervous system infections, substance abuse, and tobacco chewing, remains unknown
because of the lack of relevant studies. Approximately 16% of
Sri Lankans are known to use smokeless tobacco products.11
Chang et al Stroke Prevalence in Sri Lanka 2967
Table. Demographic Characteristics, Clinical Presentations, and Stroke Risk Factors of Adults Aged ≥18 y With an Ever Diagnosis
of Stroke
Patients With Stroke in the Study*
Characteristics
Age, y
Men
Women
Total
64.7 (11.9)
61.6 (13.0)
63.7 (12.1)
Sri Lankan Population
32.0
Sinhalese ethnicity
15 (93.8)
8 (100.0)
23 (95.8)
Income <Rs. 10 000 (USD 75)
13 (81.2)
4 (50.0)
17 (70.8)
NA
8 (66.7)
1 (50.0)
9 (64.3)
NA
14 (87.5)
8 (100)
22 (91.7)
NA
Gave up job after stroke†
82
Stroke symptoms‡
Loss of strength/numbness in the face, arm, or
leg on one side
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Difficulty speaking or understanding
9 (56.2)
5 (62.5)
14 (58.3)
Blurring of vision, double vision or loss of
vision/field
2 (12.5)
0 (0.0)
2 (8.3)
Severe and unusual headache (worst-ever
headache)
0 (0.0)
0 (0.0)
0 (0.0)
Loss of balance
3 (18.8)
1 (12.5)
4 (16.7)
No. of symptoms
1
7 (43.8)
3 (37.5)
10 (41.7)
2
6 (37.5)
4 (50.0)
10 (41.7)
3
3 (18.8)
1 (12.5)
4 (16.7)
NA
Risk factors
TIA/past stroke§
Hypertension
Diabetes mellitus
7 (43.8)
0 (0.0)
7 (29.2)
NA
10 (62.5)
5 (62.5)
15 (62.5)
19.3–23.76,7
5 (31.2)
3 (37.5)
8 (33.3)
10.3–14.26,8
Atrial fibrillation
0 (0.0)
0 (0.0)
0 (0.0)
NA
IHD
2 (12.5)
0 (0.0)
2 (8.3)
1.69
Smoking§
11 (68.8)
0 (0.0)
11 (45.8)
57.99
Excess alcohol§
10 (62.5)
0 (0.0)
11 (41.7)
NA
3 (18.8)
2 (25.0)
5 (20.8)
NA
Family history of stroke
Dyslipidemia
12.69
Obesity
20.3 in men and 36.5 in women6
≥2 risk factors§
16 (100)
3 (37.5)
19 (79.3)
Total
16 (100)
8 (100)
24 (100)
NA
IHD indicates ischemic heart disease; NA, not available; and TIA, transient ischemic attack.
*Summarized in n (%) except age given in mean (SD).
†10 who were not used at the time of stroke were removed.
‡Sudden onset and lasting >24 h.
§Significant at P<0.01.
Ours was a prevalence study, and we did not evaluate
stroke-related physical or mental disability and care needs.
However, we found that 2 of 3 stroke victims had to change
occupation or give up working because of stroke-related
disability.
The strengths of this study were many. Colombo being the
commercial metropolis of Sri Lanka provided an ideal urban
setting that is most vulnerable for accumulating stroke risk
factors and unhealthy lifestyles. We further used a robust sampling technique to ensure that the study population represented
adults exposed to varying degrees of urbanization. The use
of trained preintern medical doctors as interviewers and the
use of multiple sources in ascertaining the diagnosis of stroke
improved the quality of our data. In Sri Lanka, medical notes
(discharge summaries written in diagnosis cards, clinic notes
written in clinic books, and prescriptions), investigations, and
their reports are routinely given to patients for safe keeping,
and therefore, they were accessible to the interviewer. Stroke
was only coded if symptoms had persisted for ≥24 hours to
exclude transient ischemic attack that is a common source of
misclassification.12
The limitation of our study is that there is possibility that
we may have missed paroxysmal atrial fibrillation among
our stroke victims because longer duration ECG testing is
not done routinely in the stroke work-up. Furthermore, we
used a time-locked definition of stroke sans magnetic resonance imaging, which may have underestimated subclinical
strokes.
2968 Stroke October 2015
Conclusions
This is the first population-based study on stroke prevalence in
an urban community that is highly vulnerable to stroke in Sri
Lanka. These data may not represent the country as a whole
because of regional differences in socioeconomic status and
risk behaviors. Future studies should include participants from
urban and rural communities from different parts of the country to improve external validity.
Disclosures
None.
References
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Prevalence of Stroke and Its Risk Factors in Urban Sri Lanka: Population-Based Study
Thashi Chang, Seneth Gajasinghe and Carukshi Arambepola
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Stroke. 2015;46:2965-2968; originally published online September 1, 2015;
doi: 10.1161/STROKEAHA.115.010203
Stroke is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 2015 American Heart Association, Inc. All rights reserved.
Print ISSN: 0039-2499. Online ISSN: 1524-4628
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Data Supplement (unedited) at:
http://stroke.ahajournals.org/content/suppl/2015/09/01/STROKEAHA.115.010203.DC1
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SUPPLEMENTAL MATERIAL
1
Supplemental methods
Stroke questionnaire
There were two components in the interviewer-administered stroke questionnaire: Household
identification and individual
Household identification questionnaire:
Age and sex of each current household member
Individual questionnaire (in four parts):
Diagnosis of stroke and stroke risk factors of participants was made by triangulation of
several methods (history obtained using an interviewer-based-questionnaire and confirmed by
perusal of documental evidence such as diagnosis cards issued by hospitals and general
practitioners, brain scan reports, clinic follow-up records and drug prescription cards. In Sri
Lanka, medical notes - discharge summaries written in ‘diagnosis cards’, clinic notes written
in ‘clinic books’ and prescriptions; investigations and their reports are routinely given to
patients for safe keeping and were therefore accessible to the interviewer).
Part I: Demographic and socio-economic characteristics of participant
 Age at last birthday, sex, ethnicity, current and previous occupations, reasons for
change in occupation, monthly household income
Part II: Diagnosis of stroke
 Whether ‘ever experienced one or more of the following symptoms that was of
sudden onset and lasted for more than 24 hours’
o Loss of strength (weakness) and/or numbness of face, arm and/or leg on one side
o Difficulty speaking or understanding
o Blurring of vision, double vision, or loss of vision in one eye or part of the visual
field
o Severe and unusual headache (worst ever)
o Loss of balance
If the answer is ‘yes’ to one or more symptoms,
 Whether the patient sought any treatment for his/her symptoms; if yes, what type of
medical treatment (western, indigenous) was solicited and whether the patient was
informed by the health-care personnel that the symptoms were representative of a
stroke (corroborated from medical notes)
 Whether the patient had a brain scan; if yes, confirmation of stroke diagnosis and type
by perusing the brain scan report
Part III: Details of the stroke
 Whether symptoms experienced were the first ever episode
 If not, the number of similar episodes experienced in the past (month and year of each
episode) (confirmed by documental evidence)
2
Part IV: Risk factors of stroke
 Ever being informed/diagnosed by a medical personnel before or at the time of stroke
diagnosis of having one or more of the following conditions: transient ischaemic
attack, elevated blood pressure, diabetes mellitus, atrial fibrillation, ischaemic heart
disease and heart attack/infarct (confirmed by documental evidence)
 Any family history of stroke; if yes, relationship and age of onset of stroke
 Tobacco use: cigarettes/ beedee/ cigars/ pipes/ chewed (smokeless tobacco): quantity
and duration
 Alcohol consumption: quantity (units) and duration
 Physical activity: type and duration per day, per week and total duration
3