Violeta Díaz

Vascular Factors and Risk of Dementia: Design of the Three-City Study and Baseline Characteristics of the Study Population

Objective: To describe the baseline characteristics of the participants in the Three-City (3C) Study, a study aiming to evaluate the risk of dementia and cognitive impairment attributable to vascular factors. Methods: Between 1999 and 2001, 9,693 persons aged 65 years and over, noninstitutionalized, were recruited from the electoral rolls of three French cities, i.e. Bordeaux, Dijon and Montpellier. Health-related data were collected during face-to-face interviews using standardized questionnaires. The baseline examination included cognitive testing and diagnosis of dementia, and assessment of vascular risk factors, including blood pressure measurements, ultrasound examination of the carotid arteries, and measurement of biological parameters (glycemia, total, high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides, creatinemia); 3,442 magnetic resonance imaging (MRI) examinations were performed in subjects aged 65–79. Measurements of ultrasound, blood, and MRI parameters were centralized. Two follow-up examinations (at 2 and 4 years) were planned. Results: After exclusion of the participants who had subsequently refused the medical interview, the 3C Study sample consisted of 3,649 men (39.3%) and 5,645 women, mean age 74.4 years, with a relatively high level of education and income. Forty-two percent of the participants reported to be followed up for hypertension, about one third for hypercholesterolemia, and 8% for diabetes; 65% had elevated blood pressure measures (systolic blood pressure ≧140 or diastolic blood pressure ≧90). The proportion of Mini-Mental State Examination scores below 24 was 7% and dementia was diagnosed in 2.2% of the participants. Conclusion: Distribution of baseline characteristics of the 3C Study participants suggests that this study will provide a unique opportunity to estimate the risk of dementia attributable to vascular factors.

Towards establishing MS prevalence in Latin America and the Caribbean

A very high prevalence of multiple sclerosis (MS) has been reported in some Western European and North American countries. The few surveys of MS epidemiology in South America reveal lower prevalence rates, implying that susceptibility varies between distinct ethnic groups, thus forming an important determinant of the geographic distribution of the disease. The objective of this study is to review MS prevalence estimates in different Latin American and Caribbean countries. We reviewed surveys of regional MS prevalence from 1991 to 2011. Sources included an online database, authors’ reports and proceedings or specific lectures from regional conferences. We obtained a total of 30 prevalence surveys from 15 countries, showing low/medium MS prevalence rates. Both the number and the quality of prevalence surveys have greatly improved in this region over recent decades. This is the first collaborative study to map the regional frequency of MS. Establishment of standardized methods and joint epidemiological studies will advance future MS research in Latin America and the Caribbean.

Is hypothermia useful in malignant ischemic stroke? Current status and future perspectives

BACKGROUND AND AIMS In acute stroke patients, mild and moderate hypothermia with a body temperature (T core) target of 32 degrees C to 34 degrees C is being tested and has shown some promising results. The feasibility of MH to control of ICP increases in patients with malignant ischemic stroke has been proven, but controversy as to its effectiveness and safety still continues. The most recent results of clinical trials and possible future applications of MH in acute stroke patients are analyzed in this review. DESIGN, METHODS AND MATERIAL: A search in MEDLINE/PubMed was performed. The references of selected articles were investigated and the Cochrane Library searched. Articles including severe, massive, malignant or hemispheric ischemic stroke, induced hypothermia, and animal studies with focal cerebral or brain ischemic models were considered. RESULTS 196 patients with ischemic stroke treated with hypothermia have been reported in eleven small clinical studies, with a mild benefit of MH over the mortality rate and final outcome. CONCLUSIONS Moderate hypothermia ameliorates ischemic injury by multiple mechanisms. Treatment of acute ischemic stroke patients is feasible, and additional studies, including randomized clinical trials, are warranted.

Frequency and Determinants of Poststroke Cognitive Impairment at Three and Twelve Months in Chile

Background: A higher risk of poststroke cognitive impairment (CI) has been reported in Hispanics in a US cohort but has not been systematically studied in Latin America. Objectives: Our purpose was to investigate the frequencies and determinants of poststroke CI in the hispano-mestizo population of Santiago, Chile. Methods: A prospective study of hospitalized patients aged >60 years admitted with an ischemic or hemorrhagic stroke was conducted. The cognitive status was determined at 3 and 12 months after the stroke by informant questionnaires, neuropsychological testing and clinical diagnosis. Cardiovascular risk factors, brain imaging and stroke features were analyzed using regression models to establish determinants for poststroke CI. Results: A total of 164 patients (mean age = 72 ± 7.5 years) were recruited. Out of 122 patients (74%) evaluated at 3 months, 81 (66%) had CI. Out of 101 patients (62%) evaluated at 12 months, 39 (39%) had CI no dementia, and 22 (22%) were demented. The new-onset dementia frequency at 1 year was 16%. Independent determinants for dementia were higher functional impairment at hospital egress (OR = 4.0), left-hemisphere large-vessel infarction (OR = 6.9) and a larger amount of white matter changes (OR = 1.3). Conclusions: In this first study on poststroke CI in Latin America, the frequencies and determinants of poststroke CI were similar to those in other cohorts of different ethnic origin.

Alcohol and Hemorrhagic Stroke in Santiago, Chile

Background and Purpose: Hemorrhagic stroke (HS) is a major cause of disability and death worldwide. There is a dearth of information on HS from geographically defined populations in Latin America. In this study we assessed the importance of alcohol consumption as a risk factor for HS in Chile. Methods: Case-control study in Santiago, Chile, of 140 consecutive patients with CT-confirmed HS, matched by sex and age with 140 hospital controls. Alcohol consumption was measured in grams (ethanol) per week, using a questionnaire administered to the patients or caregivers or both. We defined four categories of alcohol consumption: nondrinkers (0.0 g/week), light (0.1–115 g/week), moderate (116–402.5 g/week) and heavy drinkers (>402.5 g/week). Other variables measured included diabetes mellitus (DM), cigarette smoking, arterial hypertension, liver disease and chronic use of nonsteroidal anti-inflammatory drugs (NSAID). Statistical analysis was performed with STATA 6.0® software. Results: A total of 280 subjects with a mean age of 65.5 years were studied over a 3-year period, 122 men (43.5%) and 158 women (56.5%). Alcohol intake was 394.1 g/week among cases and 174.5 g/week in controls (p = 0.01). The following odds ratios (OR) with 95% confidence intervals (CI) were found: hypertension 4.89 (2.86–10.3) and chronic use of NSAID 3.44 (2.15–12.9). Using conditional logistic regression analysis high alcohol intake was found to have a statistically significant OR of 4.47 (CI 1.14–17.2). Conclusions: In Chile, a high alcohol intake (>402.5 g/week) increased more than 4 times the risk of HS and remained a significant risk factor for HS after controlling for hypertension, cigarette smoking, liver disease, blood cholesterol levels, and chronic use of NSAID. The risk was higher in younger patients (<65 years of age).

Prognosis of Cryptogenic Ischemic Stroke: A Prospective Single-Center Study in Chile

Approximately 25%-40% of ischemic strokes are considered of unknown cause (ie, cryptogenic). The available information on associated risk factors, functional outcome, and recurrence of this subtype of stroke is limited, especially for the Chilean population. We conducted a prospective cohort study of 380 patients aged ≥ 18 years admitted consecutively to a stroke unit with demonstrated ischemic stroke. The stroke subtypes were classified according to the Trial of Org 10172 in Acute Stroke Treatment criteria. The modified Rankin Scale score and Barthel Index were used to assess functional outcome. The Kaplan-Meier product-limit method and Cox proportional hazards regression analysis were used to identify predictors of recurrent stroke during the follow-up period (mean, 2.1 years). Cryptogenic stroke (CS) was diagnosed in 76 patients (20%), 55.2% of them male, with a mean age of 62 ± 17 years. CS was the third most common stroke subtype after the large-artery disease (29%) and cardioembolic (24.4%) subtypes. After adjustment for age and sex, no vascular risk factors or laboratory parameters assessed at the time of admission were found to be predictive of CS. The CS subtype had the lowest rate of stroke recurrence at the end of the follow-up period (n = 4; 2.5% per year; odds ratio, 0.32; 95% confidence interval, 0.11-0.91; P = .022), a favorable functional outcome (mean modified Rankin Scale score, 2; mean Barthel Index, 77), and no increase in mortality risk (odds ratio, 0.73; 95% confidence interval, 0.29-1.77; P = .48). Our findings demonstrate that patients with no definite etiology identified after an extensive workup are at lower risk of recurrence and more likely to have a favorable outcome. No risk factors distinguish CS from other stroke subtypes in our study population.

Incidence of multiple sclerosis in Chile. A hospital registry study

Díaz V, Barahona J, Antinao J, Quezada R, Delgado I, Silva C, Guiloff RJ. Incidence of multiple sclerosis in Chile. A hospital registry study. 
Acta Neurol Scand: 2012: 125: 71–75. 
© 2011 John Wiley & Sons A/S.

Socioeconomic and Cardiovascular Variables Explaining Regional Variations in Stroke Mortality in Chile: An Ecological Study

Background: Regional differences in stroke mortality rates have been described in Chile. These could be related to the distribution of cardiovascular risk factors, the quality of medical care or socioeconomic status influencing incidence or case fatality rates. Our objective was to investigate variables explaining the variability in stroke mortality rates in the different regions of Chile. Methods: Adjusted stroke mortality rates in different regions were calculated for the year 2003. Variables were added from three sources: the National Death Certificate Database, the National Socioeconomic Characterization Survey and the National Health Survey. A logistic regression model was used to investigate regions, demographic variables and socioeconomic variables associated with the risk of death from stroke. A linear regression model was used to study the association of socioeconomic variables and cardiovascular risk factors with the standardized mortality rate by region and the contribution of these to the variability. Results: A twofold increase was found in adjusted stroke mortality rates among regions. Greater risk was associated with older age, female gender and residence in regions V, VII, VIII and IX. Sixty-two percent of the regional variability rate was explained by the combined prevalence of poverty (34%), diabetes (17%), sedentarism (8%) and overweight (3%). Conclusion: The risk of death from stroke in Chile is associated with age, sex and living in four specific regions of the country. The majority of the increased risk in these regions is explained by the prevalence of poverty, diabetes, a sedentary lifestyle and overweight.

Domain modeling as a basis for building a meshing tool software product line

Meshing tools are highly complex software for generating and managing geometrical discretizations. Due to their complexity, they have generally been developed by end users - physicists, forest engineers, mechanical engineers - with ad hoc methodologies and not by applying well established software engineering practices. Different meshing tools have been developed over the years, making them a good application domain for Software Product Lines (SPLs). This paper proposes building a domain model that captures the different domain characteristics such as features, goals, scenarios and a lexicon, and the relationships among them. The model is partly specified using a formal language. The domain model captures product commonalities and variabilities as well as the particular characteristics of different SPL products. The paper presents a rigorous process for building the domain model, where specific roles, activities and artifacts are identified. This process also clearly establishes consistency and completeness conditions. The usefulness of the model and the process are validated by using them to generate a software product line of Tree Stem Deformation (TSD) meshing tools. We also present Meshing Tool Generator, a software that follows the SPL approach for generating meshing tools belonging to the TSD SPL. We show how an end user can easily generate three different TSD meshing tools using Meshing Tool Generator.

Trombolisis cerebral en el adulto mayor: Caso clínico

Most studies evaluating the usefulness of intravenous thrombolysisfor acute stroke have excluded subjects aged over 80 years. Therefore there is no evidence tosupport or contraindicate this therapy in this age group. We report a 93 year-old femalesubjected to intravenous thrombolysis using tissue plasminogen activator (r-tPA), according tothe National Institute of Neurological Disorders protocol. The treatment was successful, therewere no hemorrhagic complications and three months later, the patient was practically withoutany disability. Therefore age is not an absolute contraindication for intravenous thrombolysisin elderly subjects (Rev Med Chile 2008; 136: 502-6).(