[ProCOR] Ischaemic Stroke in a Chilean Hispanic-Mestizo Population

[The incidence of ischaemic stroke subtypes in different populations seems to
vary, probably as a result of different distributions of risk factors in
populations, ethnic predisposition, and selection or classification bias.
Hypertension and atrial fibrillation were the most common risk factor and cause,
respectively, of ischemic stroke in a predominantly Hispanic-Mestizo population
in Iquique, Chile.]

Title: Incidence, Case-fatality Rate, and Prognosis of Ischaemic Stroke Subtypes
in a Predominantly Hispanic-Mestizo Population in Iquique, Chile (PISCIS
project): A Community Based Incidence Study

Author: PM Lavados, C Sacks, et al

Reference: Lancet Neurol 2007; 6: 140-48,
http://www.thelancet.com/journals/laneur/

Reviewer: Carlos Mendoza Montano, PhD, APRECOR, Guatemala, ProCOR Contributing Editor
E-mail: projhouse@intelnet.net.gt

Problem addressed: In Latin American Hispanic populations most strokes are
ischaemic. The identification of the cause of ischaemic stroke is important
because subtypes are amenable to different prevention strategies and because
different stroke mechanisms could lead to novel treatments by subtype. The
incidence of ischaemic stroke subtypes in different populations seems to vary,
probably as a result of different distributions of risk factors in populations,
ethnic predisposition, and selection or classification bias. In a previous
stroke study, the incidence of first-ever ischaemic stroke in the population of
Iquique, Chile, was slightly lower than reported in other population-based
studies. The distribution of ischaemic stroke syndromes was shown to be
different from other population studies with an excess of lacunar infarctions
and fewer partial anterior infarctions. No previous population-based study has
reported the incidence of ischaemic stroke subtypes in Latin American
populations unbiased by hospital admission or rapid death.

Purpose of study: The aim of this community-based study was to report incidence
of first-ever ischaemic stroke by cause, 30-day case-fatality rate, previously
known vascular risk factors, and prognosis at six months in the population of
Iquique which is predominantly Hispanic-Mestizo.

Location of study: Chile.

Study design: Between July 2000 and June 2002, all patients with possible stroke
or transient ischaemic attacks were identified from multiple overlapping sources
and were rapidly assessed by two field neurologists. All identified patients
were diagnosed by at least two stroke neurologists according to Trial of Org
10172 in Acute Stroke Treatment (TOAST) definitions and were followed up at 6
months. Annual incidence rates were age adjusted to WHO, European, and US
populations by the direct method to allow comparisons.

Results/Findings: A total of 239 ischaemic strokes were identified, of which 185
(77%) were first-ever cases. 151 (82%) patients were hospitalised, of whom only
70 (38%) were assessed within 6 h of symptom onset. The mean age of patients was
66.4 years (SD 14¬?9) and 56% were men. The crude annual incidence rates (per 100
000) according to stroke subtype were: cardioembolic, 9.3; large-artery disease,
2.0; small-vessel disease, 15.8; other determined cause, 0.2; and undetermined
cause, 17.4. Hypertension was the most common cardiovascular risk factor in all
subtypes and atrial fibrillation was the most common cause of cardioembolic
stroke. Case fatality at 30 days was highest in cardioembolic strokes (28%) and
lowest in small-vessel disease (0%). Dependency or death at six months was also
highest in cardioembolic strokes (62%) and lowest in small-vessel disease (21%).

Comments: Incidence and prognosis of small vessel and cardioembolic infarction
was similar to that in other populations and incidence of large-artery
atherothrombotic infarction was lower than in most previous reports.
Hypertension and atrial fibrillation were the most common risk factor and cause,
respectively, of ischemic stroke in this population. Cerebral infarction
represents the most common pathological subtype of stroke and its frequency is
likely to increase with rising age and prevalence of cardiovascular risk factors
as the country of Chile goes through the epidemiological transition. The authors
of the study concluded that their findings should help to strengthen the
national stroke programme, devoting increased resources and energy in the
prevention of cardioembolic infarction, especially those associated with atrial
fibrillation, which has the highest incidence and case-fatality rates. They also
concluded that their results should serve to improve stroke awareness and early
consultation among the population with increase access to stroke specialists.
These results should also foster research in the incidence of infarction
subtypes in other Latin American and Caribbean countries in well-designed
population-based studies.


Additional References:
1. Lavados PM, Sacks C, Prina L, et al. Incidence, 30-day case-fatality rate,
and prognosis of stroke in Iquique, Chile: a 2-year communitybased prospective
study (PISCIS project). Lancet 2005; 365: 2206-15.
2. Saposnik S, Del Brutto OH. Stroke in South America: a systematic review of
incidence, prevalence, and stroke subtypes. Stroke 2003; 34: 2103-08.

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