Over the last 10 years, significant data on stroke in the Kingdom of Saudi
Arabia were collected and resulted in a better knowledge of the magnitude of
this disorder in the community, its risk factors, and its specific features
in this part of the world. The most important studies were the Thugbah
community study on the prevalence of neurological disorders, the Eastern
Province community-based stroke register (EPSR) and the hospital-based Saudi
stroke data bank (SSDB) where more than a thousand stroke cases were
studied. The results of these 3 studies are summarized below:
Incidence and Prevalence
The crude annual incidence of stroke in the EPSR was 29.8/100,000 in the
EPSR [2] (95% CI: 25.2-34.3/100,000), a number that is extremely low in
comparison to incidence rates reported in western countries and Japan
(150-250 new cases/100,000 population/year) but within the ranges reported
in developing countries. However, when this
was standardized to the 1976 US demographic structure, it rose to
125.8/100,000/y, suggesting that the low incidence was primarily due to the
relative preponderance of younger age groups, which are less prone to
strokes, in the Saudi population.
The prevalence of stroke was estimated at 186/100,000 population in the
Thugbah study. This number is also very low in comparison with reports from
developed countries (600-800/100,000), obviously for the same reasons as for
the lower incidence.
Demographics
In all community and hospital-based studies, males outnumbered female
patients and stroke increased steadily with age. However, stroke in the
younger age groups was surprisingly frequent. Patients below age 45
accounted for 9.8 % of the patients in the EPSR and for 15.9% in the SSDB.
In comparison, patients younger than 45 years of age did not constitute more
than 3-5% in most Western epidemiological studies.
Risk Factors
Arterial hypertension was the most frequent risk factor found in 38-52% of
cases. Diabetes mellitus was found in 37-43%. The frequency of diabetes
mellitus was extremely high in all these studies when compared to what is
reported from other parts of the world. It was associated with only 12.6% of
strokes in the Lausanne stroke registry and 19.4% in the Harvard stroke
register. This high frequency may reflect the high prevalence of diabetes
mellitus in the stroke-prone age groups in the society. Cardiac disorders
were also quite frequent in Saudi stroke patients and
associated mainly with large cerebral infarcts, suggesting that
cardiac embolism plays a major role in the mechanism of these infarcts in
Saudis. In all studies, cigarette smoking did not appear to be a frequent
risk factor found in 10-19%. The same applies on carotid bruit that did not
exceed 5% of the cases in all studies. Table 1 shows the risk factors
associated with each type of stroke in the 1,000 first cases of stroke
recorded in the SSDB.
Types of stroke
Ischemic strokes were largely predominant. Cerebral infarcts constituted
80% of the stroke cases explored by brain CT in the EPSR and 76% in
the SSDB. This is similar to the figures reported in most western studies.
In the hemorrhagic strokes, intracerebral hemorrhages (ICH) predominated in
all studies, and subarachnoid hemorrhages (SAH) were rare, varying from 1.4%
to 2.2% of the
cases only. In comparison, SAH
constituted 6% of stroke cases in the Harvard stroke register and 13% in a
Japanese study. The combined frequency of strokes related to small artery
disease i.e. lacunar infarcts and cerebral hemorrhages approached 50%.This
would suggest that small artery disease, that is linked specifically to
untreated hypertension plays a major
role in stroke pathogenesis in Saudi Arabia
Outcome issues
The outcome of strokes in Saudi patients has not yet been addressed
in extenso. Most of the available data is about early or in-hospital
mortality. This was 15% in the EPSR. Mortality rates were related to the
type of stroke, being higher in cerebral hemorrhages] and the age of the
patient.