First-Ever Stroke and Transient Ischemic Attack Incidence and 30-Day Case-Fatality Rates in a Population-Based Study in Argentina
Background and Purpose—Epidemiological data about stroke are scarce in low- and middle-income Latin-American countries. We investigated annual incidence of first-ever stroke and transient ischemic attack (TIA) and 30-day case-fatality rates in a population-based setting in Tandil, Argentina.
Methods—We prospectively identified all first-ever stroke and TIA cases from overlapping sources between January 5, 2013, and April 30, 2015, in Tandil, Argentina. We calculated crude and standardized incidence rates. We estimated 30-day case-fatality rates.
Results—We identified 334 first-ever strokes and 108 TIAs. Age-standardized incidence rate per 100 000 for Segi’s World population was 76.5 (95% confidence interval [CI], 67.8–85.9) for first-ever stroke and 25.1 (95% CI, 20.2–30.7) for first-ever TIA, 56.1 (95% CI, 48.8–64.2) for ischemic stroke, 13.5 (95% CI, 9.9–17.9) for intracerebral hemorrhage, and 4.9 (95% CI, 2.7–8.1) for subarachnoid hemorrhage. Stroke incidence was slightly higher for men (87.8; 95% CI, 74.6–102.6) than for women (73.2; 95% CI, 61.7–86.1) when standardized for the Argentinean population. Thirty-day case-fatality rate was 14.7% (95% CI, 10.8–19.5) for ischemic stroke, 24.1% (95% CI, 14.2–36.6) for intracerebral hemorrhage, and 1.9% (95% CI, 0.4–5.8) for TIA.
Conclusions—This study provides the first prospective population-based stroke and TIA incidence and case-fatality estimate in Argentina. First-ever stroke incidence was lower than that reported in previous Latin-American studies, but first-ever TIA incidence was higher. Thirty-day case-fatality rates were similar to those of other population-based Latin-American studies.
Latin-American countries have low- and middle-income economies and strive to reduce the burden of noncommunicable diseases. A major limitation of these countries is the scarcity of data necessary to develop appropriate health policies. According to United Nations, Latin-American countries need to improve data collection systems required for developing health policies.1 Despite this, stroke incidence studies in Latin America have only been performed in Chile,2 Brazil,3,4 Mexico,5 and Uruguay.6 Although data are available from a former National Stroke Registry, stroke incidence remains unknown in Argentina, as in many other Latin-American countries.7
PrEViSTA, the Program for the Epidemiological Evaluation of Stroke In Tandil, Argentina, is a prospective population-based study of first-ever stroke and transient ischemic attack (TIA) incidence; distribution of risk factors; and 30-day, 6-month, and 12-month case-fatality rates and recurrence.8 In this analysis, we report first-ever stroke and TIA incidence and 30-day case-fatality rates.
Using several overlapping strategies, we enrolled all first-ever ischemic strokes (IS), intracerebral hemorrhages (ICH), subarachnoid hemorrhages, strokes of undetermined cause, and TIAs in Tandil, between January 5, 2013, and April 30, 2015 (Figure I in the online-only Data Supplement). We standardized first-ever stroke (IS+ICH+subarachnoid hemorrhage+stroke of undetermined cause) and TIA incidence rates to Argentinean, Segi’s European, European 2013, Segi’s World, and WHO World populations by the direct method. We calculated case-fatality rates and performed Kaplan–Meier analyses to estimate survival curves. We used the log-rank test (Mantel–Cox) to compare survival between groups: first-ever versus recurrent stroke, stroke types, males versus females, and age quintiles (<58, 59–68, 69–76, 77–84, and >84 years). A full description of the methods is offered elsewhere8 and in the online-only Data Supplement.
We identified 334 first-ever strokes and 108 TIAs. Crude annual first-ever stroke incidence per 100 000 was 127.9, whereas it was 105.5, 114.7, 184.7, 88.1, and 76.5 when standardized to Argentinean, Segi’s European, European 2013, WHO World, and Segi’s World populations, respectively (Table). Age-specific annual incidence rates of overall first-ever strokes and stroke types stratified by sex are displayed in Table I in the online-only Data Supplement. Annual crude first-ever stroke incidence was similar in men (125.9) and women (129.8) and increased with age (Figure II in the online-only Data Supplement). When standardized to the Argentinean population, it was slightly higher for men (87.8) than for women (73.2).
First-ever crude TIA annual incidence rates was 41.4. It was 34.4 and 37.6, when standardized for Argentinean and Segi’s European populations, respectively (Table). For first-ever stroke and TIA considered together, crude incidence rate was 169.2 (152.3 after standardization for Segi’s European population).
Thirty-day case-fatality rate was 15.6% for all cerebrovascular events, 14.7% for IS, 24.1% for ICH, 47.1% for subarachnoid hemorrhage, 75.0% for strokes of undetermined pathogenesis, and 1.9% for TIA (Table II in the online-only Data Supplement). The main cause of death was neurological (53.4%), followed by pneumonia (23.3%). Causes of death in 2 patients with TIA were recurrent fatal stroke and myocardial infarction. Survival rates were higher for first-ever than for recurrent strokes, lower for the highest 2 age quintiles, and significantly differed across stroke types (Figure III in the online-only Data Supplement). There were no differences between men and women.
In this prospective study of first-ever stroke and TIA incidence and 30-day case-fatality rate conducted in Tandil, Argentina, first-ever stroke annual incidence rate was lower, but TIA rate was higher than that reported in previous studies conducted in other Latin-American countries.2–6 Overall case-fatality rates were similar.
Differences in first-ever stroke incidence may be explained by distinctive population characteristics (eg, education, income, or lower risk factor prevalence, either because of differences between countries or temporal changes in prevalence)2–6 and possibly by improvements in the control of vascular risk factors in Argentina during the past 12 years (Figures IV and V in the online-only Data Supplement).
Crude annual first-ever stroke incident rates were similar among women and men, but higher for men than for women for the age group of 65 to 74 years. Among those aged ≥85 years, women showed higher rates than men, presumably because of adverse selection among the latter.
Standardized first-ever IS annual incidence rate was 56.1 (Segi’s World population), lower than that in Chile (66.5)2 and Brazil (86.0).3 Likewise, first-ever ICH incidence in Tandil (13.5) was lower than that in Chile (22.1)2 and similar to Brazil (12.9).3
First-ever TIA standardized annual incidence rates were higher in Argentina than in Brazil (37.6 versus 14.0, Segi’s European population).9 The proportion of TIAs with regard to all cerebrovascular events in Argentina (24.4% of the patients with first-ever events) was the highest reported in Latin America (Chile 6.8%2 and Brazil 10.6%3), meaning that case ascertainment was highly efficient.
Overall first-ever stroke case-fatality rate at 30 days was similar to that reported in most Latin-American population-based studies.2–4 Case-fatality rates for IS and ICH were also comparable to other Latin-American studies, except for the highest rate seen in Matao, Brazil.2,5 Tandil lacks a formal stroke program and 24×7 on-call neurology service, intravenous thrombolysis is only seldom offered, and mechanical thrombectomy is not done. This is the general picture for most healthcare centers in the country.10
This study, conducted according to rigorous methodological standards, provides the first prospective population-based first-ever stroke and TIA incidence and case-fatality estimate in Argentina. Although the relatively low stroke rates are encouraging, the high case-fatality rates should be regarded as red flag showing the need for urgent acute stroke treatment policies.
We thank Paola Lascurain (study coordinator), Marilia García (data set manager), Francis Galdon (regulatory affairs), Dr Francisco Muñoz, Dr María Eugenia González Toledo, Dr Fátima Pagani Cassará (stroke training for study investigators), Mario Caramutti, and Dr Alejandro Turek for their exceptional support.
Sources of Funding
The study was partially funded by unrestricted grants from Genzyme Argentina and LePetit Pharma. Educational activities were supported by Laboratorio Roche SAQeI (good clinical practice) and Boehringer Ingelheim (community stroke awareness). Dr Sposato was partially funded by the Edward & Alma Saraydar Neurosciences Fund. Dr Saposnik is supported by the Distinguished Clinician Scientist Award given by Heart and Stroke Foundation of Canada.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.116.013637/-/DC1.
- Received March 31, 2016.
- Revision received March 31, 2016.
- Accepted April 5, 2016.
- © 2016 American Heart Association, Inc.
- 1.↵General Assembly, United Nations. Political declaration of the high-level meeting of the general assembly on the prevention and control of non-communicable diseases. United Nations Web site. http://www.un.org/en/ga/search/view_doc.asp?symbol=%20A/RES/66/2. Accessed April 5, 2016.
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