Abstract
The Hispanic population caries a disproportionate burden of stroke compared to the non-Hispanic White population. Most studies have been conducted on Caribbean Hispanics, indicating a need to better understand the characteristics of stroke and its prevalence among the Hispanic populations of Mexican descent. In this report, data were collected in the El Paso/US-Mexico border region, where 82% of the population is Mexican Hispanic, through a retrospective study of ischemic stroke from 2005 to 2010. Odds ratios (OR), 95% confidence intervals (CI), logistic regression and multivariate analysis of the odds ratios adjusted for other variables, were used to analyze the effects of various risk factors on ischemic stroke. The metabolic syndrome and its components, specifically hypertension, diabetes, and dyslipidemia appeared to be strongly associated with ischemic stroke in the Mexican Hispanic population. Mexican Hispanic ischemic stroke patients were nearly seven times more likely to have this syndrome, compared to Mexican Hispanic controls from the National Health and Nutrition Examination Survey. Likewise, the patients were nearly forty times more likely to have hypertension and eleven times more likely to have diabetes. Efforts to prevent ischemic stroke and limit its impact in the Mexican Hispanic population should focus on controlling hypertension and diabetes.
Keywords: Metabolic Syndrome, risk factors, Ischemic Stroke, Mexican Hispanic, Epidemiology
Introduction
Stroke remains a major public health burden in the United States. Despite advances in treatment and prevention, stroke has remained a top five cause of mortality since 1935 (1). Recently, in the United States, stroke moved from the third leading cause of mortality to the fourth, but remains a significant cause of mortality (2). In addition to mortality, stroke is the leading cause of disability in the Western world (3) and is a dramatically increasing in developing countries (4). It is estimated that the health care costs of strokes, between 2005 and 2050, will approach $2.2 trillion (5).
A body of evidence has emerged for ethnic disparities in stroke incidence, subtype, severity, risk factors and mortality (6-10). The most alarming figures in relation to the stroke are the discrepancies of the burden of mortality, disability and the cost between ethnic groups, specifically among African Americans and Hispanics (11, 12). Among Hispanics, stroke represents 5.1% of all deaths and the projected per capita spending for stroke is $17,201, second only to African Americans (5); demonstrating that the burden of stroke is higher among Hispanic populations as compared to all others (14). It has also been documented that Hispanics have an earlier age of onset, an overall greater incidence, and a greater recurrence of stroke (15). A possible explanation for this discrepancy is the fact that Hispanics have a higher prevalence of the metabolic syndrome and diabetes mellitus compared to African Americans or non-Hispanic Whites (14).
Most studies have been conducted in Cuban, Dominican, Puerto Rican and South American Hispanic populations and not those of Mexican descent (16). A recent report found significant differences in the frequency of different risk factors, stroke subtypes and severity, and outcomes between Mexican and Caribbean Hispanics, highlighting the heterogeneity of the Hispanic ethnic group (17). Hispanics of Mexican origin are a unique population with different genetics and population dynamics and need to be considered separately from other Hispanic populations (18).
Being situated adjacent to Juarez, Mexico, El Paso is one of the few counties in the United States whose population is primarily Hispanic of Mexican origin. According to the 2010 census, El Paso County had a population of over 800,000 with 651,727 individuals of Hispanic origin, roughly 82% of the population. With these unique population dynamics, the population of El Paso County provides tremendous insight into ischemic stroke characteristics within the Mexican Hispanic population.
Aims
The El Paso Stroke (ElPasoStroke) database was established to characterize ischemic stroke among the Mexican Hispanic population in the US-Mexico border area for a better understanding of ethnic differences in risk factors and the association of risk factors with odds of ischemic stroke in the Mexican Hispanic population.
Methods
Study Population
ElPasoStroke is composed of 546 ischemic stroke subjects identified through a retrospective chart review of all subjects with the ICD-9 diagnosis codes of 434.00/.01 (cerebral thrombosis with/without infarction), 434.10/.11 (cerebral embolism with/without infarction), and 434.90/.91 (cerebral artery occlusion, unspecified with/without infarction) from 2005 to 2010 at University Medical Center, El Paso (UMC), the only level one trauma center and the primary referral hospital in the region. This study has been conducted in accordance with an approved protocol from the institutional review board (IRB) at Texas Tech University Health Sciences Center (TTUHSC). The database was compiled through detailed review of each chart acquired through the ICD-9 search. Charts were reviewed for the following information: demographic information (year of birth, year of admission, gender, and ethnicity), stroke information (type, family history of stroke, and personal history of stroke), comorbid conditions/risk factors [diabetes (including glucose level on admission), hypertension (including blood pressure on admission), dyslipidemia, height and weight, illicit drug use (including type), heart disease (including type), lung disease, tobacco use (including type and duration), and alcohol abuse]. Subjects were excluded based on the following criteria: incomplete medical record; age less than 18 years; traumatic, infectious, hemorrhagic or post-operative stroke etiology; presence of brain tumor; no radiographic evidence of infarct; Hispanic with birthplace outside of the border region (and therefore not of Mexican descent); Asian, Black, or Native American of White origin. Age of onset was calculated by subtracting year of birth from year of admission, without respect for months. BMI was calculated through standard formula (kg/m2). The metabolic syndrome was defined as the presence of three or more of: central obesity, elevated triglycerides, diminished high-density lipoprotein (HDL), dyslipidemia, systemic hypertension, or elevated fasting glucose (20).
Data Analysis
The prevalence of each of the gathered data-points was calculated, with means, medians, modes and ranges calculated for continuous data, specifically age and BMI. The data were then stratified by ethnicity for Mexican Hispanics and non-Hispanic Whites (with exceptions for age and BMI due to small sample size). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using SAS software comparing Mexican Hispanics and non-Hispanic Whites from the ElPasoStroke for family and personal history of stroke, and risk factors for ischemic stroke. The percentage of strokes by ethnicity in the study population was also compared to those ethnicities in the overall El Paso County population using a Chi-Squared statistical test.
Data from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) (21) were used as a comparison control group. These data years were chosen to match the average dates of our data collection. Subjects were assigned a random number via a random number generator to more effectively utilize the data. Survey data were used to mimic the accuracy of a patient interview (the source of most information in the medical records) as both are based on recollection, with the exception of age and BMI. In the case that multiple variables were used in NHANES for a single ElPasoStroke data-point, the subject was counted as having the condition if one or more of the variables was positive. Presence or absence of the metabolic syndrome was calculated in the same manner as ElPasoStroke. Alcohol abuse was considered present if subjects consumed more than three drinks per day in the last year. Subject exclusion criteria were followed as in ElPasoStroke. In order to match the controls, a 1:2 case to control ratio was used, so the last 1,010 cases (ordered by random number) were chosen from NHANES as the control group. Odds ratios and 95% confidence intervals (CI) were calculated for the aforementioned study risk factors. Data were stratified by age into the following age groups: age from 18 to 49, age 50 to 59, age 60 to 69, and age 70 to 98. ORs and 95% CIs were calculated for each stratified age group, on one occasion there was no subject that met the criteria for the risk factor (in the 70 to 98 age group for illicit drug use in the NHANES group) in which case one (1) was substituted for zero (0) to allow for calculation of odds ratios.
Logistic regression and multivariate analysis of the odds ratios adjusted for other variables, was used to analyze the effects of various risk factors on ischemic stroke. In order to perform this analysis, we selected 82 (there were 41 Non-Hispanic White stroke subjects from ElPasoStroke and using the same 1:2 ratio of cases : controls as previously used, 82 controls were required for this group) random non-Hispanic White stroke-free NHANES subjects, using the method as previously explained, as controls making a total population (n) of 1638 for this analysis. These data were tabulated using the Logistic Procedure in SAS software. From the total population, 6 observations were dropped due to lack of response giving a 1632 total observations used.
Results
Characteristics of ElPasoStroke
Of the 546 cases of stroke that met the inclusion criteria 272 (49.82%) were male, 274 (50.18%) were female, and 505 were Hispanic of Mexican origin (92.49%). Of all the ICD-9 codes gathered, code 434.91 was the most prevalent with 517 (94.69%) subjects assigned. Only 58 (10.62%) subjects had a family history of stroke, with the mother and father being nearly equal (23 and 21, respectively) in prevalence, while 160 (29.30%) subjects had suffered a previous stroke themselves, with 28 having suffered more than one previous stroke. Of the risk factors for stroke assessed, hypertension was the most prevalent with 493 (90.29%) subjects meeting this criterion. Diabetes was the next most prevalent with 304 (55.68%) subjects meeting this criterion. The other risk factors and co-morbidities had the following prevalence counts and percentages, respectively: dyslipidemia (244, 44.69%), obesity (110, 20.15%), illicit drug use (30, 5.49%), heart disease (232, 42.49%), lung disease (19, 3.48%), tobacco use (214, 39.19%), alcohol abuse (119, 21.79%), metabolic syndrome (207, 37.91%). The demographic data for the group are detailed in Table 1. The expected number of strokes over the five year study period in the study population based on the population of El Paso County, stratified by ethnicity, was 467 for Mexican Hispanic and 79 for non-Hispanic White. The Chi-squared statistic calculated to compare the expected number and the actual number returned a two-tailed p value of <.0001.
Table 1. Summary of ElPasoStroke Database.
| Summary of ElPasoStroke | |||||
|---|---|---|---|---|---|
| Entire ElPasoStroke Database | ElPasoStroke Hispanic Group | ||||
| Category | Sub-Category | Count | Prevalence | Count | Prevalence |
| Total Cases | Total | 546 | 100.00% | 505 | 100.00% |
| Gender | Male | 272 | 49.82% | 248 | 49.11% |
| Female | 274 | 50.18% | 257 | 50.54% | |
| Ethnicity | Hispanic | 505 | 92.49% | ||
| White | 41 | 7.51% | |||
| ICD-9 Code | 434.01 | 11 | 2.01% | ||
| 434.11 | 14 | 2.56% | |||
| 434.90 | 4 | 0.73% | |||
| 434.91 | 517 | 94.69% | |||
| Family History | Total | 58 | 10.62% | 54 | 10.69% |
| Mother | 23 | 4.21% | |||
| Father | 21 | 3.85% | |||
| Sibling | 9 | 1.65% | |||
| Personal History | at least 1 | 160 | 29.30% | 152 | 30.10% |
| more than 1 | 28 | 5.13% | 26 | 5.15% | |
| Diabetes | Total | 304 | 55.68% | 291 | 57.62% |
| Hypertension | Total | 493 | 90.29% | 454 | 89.90% |
| Dyslipidemia | Total | 244 | 44.69% | 227 | 44.95% |
| Obesity | Total | 110 | 20.15% | 104 | 20.59% |
| Illicit Drug Use | Total | 30 | 5.49% | 26 | 5.15% |
| Heart Disease | Total | 232 | 42.49% | 212 | 41.98% |
| Lung Disease | Total | 19 | 3.48% | 17 | 3.37% |
| Tobacco Use | Total | 214 | 39.19% | 198 | 39.21% |
| Alcohol Abuse | Total | 119 | 21.79% | 113 | 22.38% |
| Metabolic Syndrome | Total | 207 | 37.91% | 196 | 38.81% |
| Summary Statistics | |||||
| Age | Mean | 64.91 | 64.95 | ||
| Median | 65 | 65 | |||
| Mode | 64 | 64 | |||
| Range | 24 to 98 | 24 to 98 | |||
| Body Mass Index | Mean | 29 | 29 | ||
| Median | 28 | 28 | |||
| Mode | 31 | 31 | |||
| Range | 15 to 54 | 18 to 49 | |||
Mexican Hispanic Group in ElPasoStroke
Since Mexican Hispanic stroke subjects dominate ElPasoStroke population (92.49%), most epidemiological characteristics were similar, including gender ratio (49.11/50.89), percentage of family history of stroke (10.69%) with nearly equal mother/father ratio (20/21), percentage of personal history of stroke (30.10%), with 26 subjects having suffered more than one stroke. Likewise, of the risk factors for stroke assessed, hypertension (89.90%) and diabetes (57.62%) were the most prevalent. Other risk factors and co-morbidities had the similar prevalence respectively: dyslipidemia (227, 44.95%), obesity (104, 20.59%), illicit drug use (26, 5.15%), heart disease (212, 41.98%), lung disease (17, 3.37%), tobacco use (198, 39.21%), alcohol abuse (113, 22.38%), metabolic syndrome (196, 38.81%). The epidemiological and demographic data for the group are detailed in Table 1.
Comparison of ElPasoStroke Ethnic Groups
The ORs for total thirteen risk factors and comorbidities generated by comparing the Mexican Hispanic ischemic stroke group to the non-Hispanic White ischemic stroke group were as follows (95% CI): family history of stroke 1.11 (0.38, 3.23), personal history of stroke 1.78 (0.80, 3.94), male gender 0.68 (0.36, 1.30), diabetes 2.93 (1.48, 5.79), hypertension 0.46 (0.11, 1.95), dyslipidemia 1.15 (0.60, 2.20), obesity 1.51 (0.62, 3.69), illicit drug use 0.50 (0.17, 1.52), heart disease 0.76 (0.40, 1.44), lung disease 0.70 (0.15, 3.05), tobacco use 1.01 (0.52, 1.94), alcohol abuse 1.68 (0.69, 4.10), metabolic syndrome 1.73 (0.85, 3.53). OR (95% CI) for only one risk factor, diabetes, was significant (Table 2).
Table 2. Results of ElPasoStroke Ethnic Group Comparison.
| Univariate Analysis of Risk Factors for Ischemic Stroke Between Ethnic Groups of Stroke Subjects within ElPasoStroke | |||||||
|---|---|---|---|---|---|---|---|
| Mexican Hispanic | Non-Hispanic White | ||||||
| Total | 505 | 41 | 95% Confidence Interval | ||||
| n | % | n | % | OR | Lower Bound | Upper Bound | |
| Male Gender | 248 | 49.11% | 24 | 58.54% | 0.683527886 | 0.36 | 1.30 |
| Diabetes* | 291 | 57.62% | 13 | 31.71% | 2.928828181 | 1.48 | 5.79 |
| Hypertension | 454 | 89.90% | 39 | 95.12% | 0.456510809 | 0.11 | 1.95 |
| Dyslipidemia | 227 | 44.95% | 17 | 41.46% | 1.1527719 | 0.60 | 2.20 |
| Obesity | 104 | 20.59% | 6 | 14.63% | 1.512884456 | 0.62 | 3.69 |
| Metabolic Syndrome | 196 | 38.81% | 11 | 26.83% | 1.729920565 | 0.85 | 3.53 |
| Heart Disease | 212 | 41.98% | 20 | 48.78% | 0.759726962 | 0.40 | 1.44 |
| Lung Disease | 17 | 3.37% | 2 | 4.88% | 0.679303279 | 0.15 | 3.05 |
| Tobacco Use | 198 | 39.21% | 16 | 39.02% | 1.007736156 | 0.52 | 1.94 |
| Alcohol Abuse | 113 | 22.38% | 6 | 14.63% | 1.681547619 | 0.69 | 4.10 |
| Illicit Drug Use | 26 | 5.15% | 4 | 9.76% | 0.502087683 | 0.17 | 1.52 |
| Family History of Stroke | 54 | 10.69% | 4 | 9.76% | 1.107538803 | 0.38 | 3.23 |
| More than One Previous Stroke | 152 | 30.10% | 8 | 19.51% | 1.776203966 | 0.80 | 3.94 |
| More than Two Previous Strokes | 26 | 5.15% | 2 | 4.88% | 1.058455115 | 0.24 | 4.63 |
Statistically Significant
Comparison between ElPasoStroke Ischemic Stroke and NHANES normal Mexican Hispanics
Evaluating the ORs for all eleven risk factors and co-morbidities of the ElPasoStroke Mexican Hispanic ischemic stroke group compared to the NHANES Mexican Hispanic stroke-free group identified seven significant risk factors (95% CI): diabetes 11.01 (8.45, 14.35), hypertension 39.70 (28.53, 55.24), dyslipidemia 2.82 (2.24, 3.54), obesity 0.44 (0.34, 0.57), illicit drug use 0.15 (0.10, 0.23), heart disease 15.16 (10.74, 21.40), metabolic syndrome 6.56 (4.95, 8.70) (Table 3).
Table 3. Odds Ratios Comparing ElPasoStroke Mexican Hispanic Ischemic Stroke Group to NHANES Mexican Stroke-free Group.
| Univariate Analysis of Risk Factors for Ischemic Stroke in the Mexican Hispanic Population | |||||||
|---|---|---|---|---|---|---|---|
| Cases (ElPasoStroke) | Controls (NHANES) | ||||||
| Total | 505 | 1010 | 95% Confidence Interval | ||||
| n | % | n | % | OR | Lower Bound | Upper Bound | |
| Male Gender | 248 | 49.11% | 494 | 48.91% | 1.01 | 0.81 | 1.25 |
| Diabetes* | 291 | 57.62% | 111 | 10.99% | 11.01 | 8.45 | 14.35 |
| Hypertension* | 454 | 89.90% | 185 | 18.32% | 39.70 | 28.53 | 55.24 |
| Dyslipidemia* | 227 | 44.95% | 227 | 22.48% | 2.82 | 2.24 | 3.54 |
| Obesity* | 104 | 20.59% | 374 | 37.03% | 0.44 | 0.34 | 0.57 |
| Metabolic Syndrome* | 196 | 38.81% | 89 | 8.81% | 6.56 | 4.95 | 8.70 |
| Heart Disease* | 212 | 41.98% | 46 | 4.55% | 15.16 | 10.74 | 21.40 |
| Lung Disease | 17 | 3.37% | 39 | 3.86% | 0.87 | 0.49 | 1.55 |
| Tobacco Use | 198 | 39.21% | 372 | 36.83% | 1.11 | 0.89 | 1.38 |
| Alcohol Abuse | 113 | 22.38% | 223 | 22.08% | 1.02 | 0.79 | 1.32 |
| Illicit Drug Use* | 26 | 5.15% | 265 | 26.24% | 0.15 | 0.10 | 0.23 |
Statistically Significant
Stratification by Age
Among the eleven risk factors and co-morbidities examined in the 18 to 49 year old group, the ORs (95% CI) were significant for following six risk factors: diabetes 22.88 (10.98, 47.67), hypertension 52.24 (26.03, 104.84), dyslipidemia 5.14 (2.85, 9.28), illicit drug use 0.48 (0.24, 0.94), heart disease 58.83 (20.72, 167.04), and metabolic syndrome 30.90 (12.48, 76.53).
In the 50 to 59 year old group, the ORs (95% CI) were significant for following five risk factors: diabetes 4.92 (2.91, 8.33), hypertension 13.10 (6.95, 24.69), obesity 0.32 (0.19, 0.55), heart disease 6.35 (3.22, 12.54), and metabolic syndrome 2.25 (1.30, 3.87).
In the 60 to 69 year old group, the ORs (95% CI) were significant for following five risk factors: diabetes 6.86 (4.06, 11.59), hypertension 30.19 (12.50, 72.94), obesity 0.40 (0.24, 0.66), heart disease 5.23 (2.67, 10.23), and metabolic syndrome 4.17 (2.48, 7.02).
In the 70 to 98 year old group, the ORs (95% CI) were significant for following six risk factors: diabetes 2.67 (1.54, 4.61), hypertension 13.59 (6.93, 26.67), obesity 0.37 (0.20, 0.68), heart disease 5.32 (2.84, 9.98), lung disease 0.35 (0.14, 0.87), and alcohol abuse 3.43 (1.29, 9.11) (Table 4).
Table 4. Odds Ratios Stratified by Age Comparing ElPasoStroke Mexican Hispanic Ischemic Group to NHANES Mexican Hispanic Stroke-free Group.
| Risk Factors for Ischemic Stroke | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cumulative (n=1515) | 18 to 49 (n=682) | 50 to 59 (n=275) | 60 to 69 (n=282) | 70 to 98 (n=271) | ||||||||||||||||
| Odds Ratio | 95% CI | Odds Ratio | 95% CI | Odds Ratio | 95% CI | Odds Ratio | 95% CI | Odds Ratio | 95% CI | |||||||||||
| Diabetes | 11.01 | * | 8.45 | 14.35 | 22.88 | * | 10.98 | 47.67 | 4.92 | * | 2.91 | 8.33 | 6.86 | * | 4.06 | 11.59 | 2.67 | * | 1.54 | 4.61 |
| Hypertension | 39.70 | * | 28.53 | 55.24 | 52.24 | * | 26.03 | 104.84 | 13.10 | * | 6.95 | 24.69 | 30.19 | * | 12.50 | 72.94 | 13.59 | * | 6.93 | 26.67 |
| Dyslipidemia | 2.82 | * | 2.24 | 3.54 | 5.14 | * | 2.85 | 9.28 | 1.20 | 0.74 | 1.95 | 1.54 | 0.96 | 2.46 | 1.16 | 0.68 | 1.98 | |||
| Obesity | 0.44 | * | 0.34 | 0.57 | 0.80 | 0.44 | 1.47 | 0.32 | * | 0.19 | 0.55 | 0.40 | * | 0.24 | 0.66 | 0.37 | * | 0.20 | 0.68 | |
| Metabolic Syndrome | 6.56 | * | 4.95 | 8.70 | 30.90 | * | 12.48 | 76.53 | 2.25 | * | 1.30 | 3.87 | 4.17 | * | 2.48 | 7.02 | 1.70 | 0.94 | 3.08 | |
| Gender | 1.01 | 0.81 | 1.25 | 1.05 | 0.61 | 1.81 | 1.12 | 0.70 | 1.81 | 1.11 | 0.69 | 1.77 | 1.18 | 0.70 | 2.00 | |||||
| Heart Disease | 15.16 | * | 10.74 | 21.40 | 58.83 | * | 20.72 | 167.04 | 6.35 | * | 3.22 | 12.54 | 5.23 | * | 2.67 | 10.23 | 5.32 | * | 2.84 | 9.98 |
| Lung Disease | 0.87 | 0.49 | 1.55 | 0.69 | 0.09 | 5.33 | 0.79 | 0.19 | 3.39 | 0.45 | 0.11 | 1.77 | 0.35 | * | 0.14 | 0.87 | ||||
| Tobacco Use | 1.11 | 0.89 | 1.38 | 0.98 | 0.53 | 1.79 | 0.75 | 0.46 | 1.20 | 1.15 | 0.71 | 1.88 | 0.76 | 0.45 | 1.29 | |||||
| Alcohol Abuse | 1.02 | 0.79 | 1.32 | 1.57 | 0.89 | 2.77 | 1.81 | 0.99 | 3.30 | 1.41 | 0.75 | 2.64 | 3.43 | * | 1.29 | 9.11 | ||||
| Illicit Drug Use | 0.15 | * | 0.10 | 0.23 | 0.48 | * | 0.24 | 0.94 | 0.18 | * | 0.08 | 0.39 | 0.30 | 0.06 | 1.45 | 1.72 | 0.19 | 15.64 | ||
Statistically Significant
Logistic Regression and Multivariate Analysis
Of all variables tested, only age, hypertension, heart disease, metabolic syndrome, and Mexican Hispanic ethnicity were jointly significant using this model. Using the results of this model, each year increase in age increases the odds of having an ischemic stroke 1.039 times (1.028, 1.050). Further data demonstrate that the odds of suffering a stroke were 11.83 (8.20, 17.09) times greater with hypertension, 4.77 (3.19, 7.15) times with heart disease, 3.46 (2.26, 5.31) times with the metabolic syndrome, and 1.577 (0.92, 2.71) times for being of Mexican Hispanic origin (although this parameter was not significant) (Table 5).
Table 5.
Logistic Regression Analysis comparing ElPasoStroke to NHANES Stroke-free Group.
| Logistic Regression Analysis of Risk Factors for Ischemic Stroke in the Mexican Hispanic Population | |||
|---|---|---|---|
| 95% Confidence Interval | |||
| Risk Factor | Odds Ratio | Lower Bound | Upper Bound |
| Age* | 1.039 | 1.028 | 1.05 |
| Hypertension* | 11.83 | 8.2 | 17.09 |
| Heart Disease* | 4.77 | 3.19 | 7.15 |
| Metabolic Syndrome* | 3.46 | 2.26 | 5.31 |
| Mexican Hispanic Ethnicity | 1.577 | 0.92 | 2.71 |
Statistically Significant
Discussion
Our results demonstrate the unique characteristics of ischemic stroke within the Mexican Hispanic population of the El Paso border region. The burden of ischemic stroke on the Mexican Hispanic population was significantly higher than expected (p <.0001); demonstrating the importance of targeting preventative measures specifically to the Mexican Hispanic population.
Metabolic syndrome may have a greater impact on Mexican Hispanics
Ischemic stroke in the Mexican Hispanic population had a greater recurrence as demonstrated by the higher percentage of subjects with a past history of stroke (30.10% compared to 19.51% in non-Hispanic Whites), although this difference was not statistically significant probably due to the small sample size of non-Hispanic Whites. These findings are consistent with those published from the Brain Attack Surveillance in Corpus Christi (BASIC) dataset (22, 23). Our findings of association of ischemic stroke with diabetes and hypertension are similar with those published from the BASIC study (24), although our study is specifically focused on ischemic stroke. Additional findings from the BASIC study demonstrated some linkage between family history of stroke and certain factors of stroke onset, severity, and outcome (25), but did not compare the prevalence of family history of stroke between ethnic groups. We found that there was no significant contribution of genetic or familial link. Our data illustrate the increased role of diabetes and the metabolic syndrome among Mexican Hispanics (Table 2), making diabetes an important focus for ischemic stroke screening and prevention.
Our results suggest that patients with ischemic stroke were nearly seven times more likely to have the metabolic syndrome, nearly forty times more likely to have hypertension, over eleven times more likely to have diabetes and almost three times more likely to have dyslipidemia (Table 3). These values were especially pronounced when the data were stratified (Table 4), which suggest that these risk factors have the greatest impact on the younger age group (age 18 to 49) whereas their impact declines with advancing age. This demonstrates the vascular instability from these conditions occurs at a far earlier age than would occur without these conditions. This is further demonstrated by the impact of heart disease on ischemic stroke in the younger age group (age 18 to 49), where the odds of ischemic stroke are over 48 times the risk compared to those without heart disease.
It is interesting to note the apparent protective value of obesity on stroke. Curtis et. al. suggested that “among patients with chronic disease excess weight is paradoxically associated with a decreased risk of adverse outcomes” (26). This is consistent with other published findings which confirm the presence of the “Obesity Paradox” (27-29). Cumulatively and among those 18 to 59 years of age, illicit drug use was a protective factor; as paradoxical as the obesity findings. This may be due to reporting bias or due to the fact that any illicit drug was considered as drug abuse, as not all illicit drugs have been linked to an increased risk of cardiovascular diseases (30). Alcohol abuse and lung disease were only significant in the 70 to 98 year old age group. This may be due to study artifact or may demonstrate the deleterious effects of alcohol and lung disease (possibly from tobacco) that accumulate over time rather than immediate impact (31). Although moderate alcohol consumption has been linked with a reduced risk of ischemic stroke (32), these findings may suggest that chronic moderate to heavy consumption of alcohol increases the risk of ischemic stroke in Mexican Hispanics, although further research would be necessary. The logistic regression and multivariate analysis shown in Table 5, suggests that Mexican Hispanic ethnicity itself is nearly a significant independent risk factor for ischemic stroke and likely would be with an increased sample size (24).
Limitations
The retrospective nature and the reliance on subjective data found in medical records may be considered a limitation. Some important risk factors for stroke, such as atrial fibrillation, were not included in this study due to missing data caused by diversified clinical attentions. Prevalence parameters defined in this study may be underestimated. Every effort was made to ensure that the data collection was accurate and complete. But these efforts did require assumptions to be made about missing data which could have had an adverse impact on the results. Further, the age ranges and mean ages of the ElPasoStroke Mexican Hispanic group and the NHANES Mexican Hispanic group were different making the data harder to match, which we tried to overcome with the aforementioned match of gender and age stratification. Further efforts to overcome these differences came through the use of logistic regression and multivariate analysis which allowed us to control for other factors and still demonstrated the impact of hypertension and the metabolic syndrome on the odds of stroke. In addition, a prospective study has been initiated to validate these initial findings.
The potential guidance for future assessment
Based on the results, consideration for more aggressive treatment of hypertension among Mexican Hispanic patients is warranted to lower the risk of ischemic stroke. Additionally, if a patient of Mexican Hispanic origin is found to have the metabolic syndrome but has blood pressures, blood glucose levels, or cholesterol levels below the standard range of treatment, they may be candidates for early pharmacological treatment and have goals lower than the general population in order to reduce the risk of ischemic stroke. These potential guidelines and goals are especially important for those under the age of fifty, as the metabolic syndrome and its risk factors have the greatest negative impact among this age group. This proposed assessment for risk of ischemic stroke is validated by a recent study on ischemic stroke outcomes, indicating that risk-adjusted rates of longer length of stay in hospital were higher among Hispanic and African American stroke patients (12).
Conclusions
The uniqueness of this study, as to the location performed and the population sampled, in addition to the sample size and comprehensive nature of the data are significant strengths. This study has demonstrated that the metabolic syndrome and its components have a significant impact on odds of stroke among the Mexican Hispanic population of the El Paso border region. Efforts to prevent stroke and its associated burdens of disability and mortality should be aimed at the control of hypertension and diabetes, specifically among Mexican Hispanic population.
Acknowledgments
We would like to thank Kathrene Tajnert, Benjamin Buchanan, Katrina DeLeon, Chau Vu, Nancy Casner and Rod Chiodini for their efforts and help with this project. This study was partially funded by Coldwell foundation (JZ). JZ is also supported by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health.
References
- 1.Hoyert D. 75 years of mortality in the United States, 1935-2010. NCHS Data Brief. 2012;(88):1–8. Epub 2012/05/24. [PubMed] [Google Scholar]
- 2.Towfighi A, Saver JL. Stroke declines from third to fourth leading cause of death in the United States: historical perspective and challenges ahead. Stroke; a journal of cerebral circulation. 2011;42(8):2351–5. doi: 10.1161/STROKEAHA.111.621904. Epub 2011/07/23. [DOI] [PubMed] [Google Scholar]
- 3.Della-Morte D, Guadagni F, Palmirotta R, Testa G, Caso V, Paciaroni M, et al. Genetics of ischemic stroke, stroke-related risk factors, stroke precursors and treatments. Pharmacogenomics. 2012;13(5):595–613. doi: 10.2217/pgs.12.14. Epub 2012/04/03. [DOI] [PubMed] [Google Scholar]
- 4.Norrving B, Kissela B. The global burden of stroke and need for a continuum of care. Neurology. 2013;80(3 Suppl 2):S5–12. doi: 10.1212/WNL.0b013e3182762397. Epub 2013/01/18. [DOI] [PubMed] [Google Scholar]
- 5.Brown DL, Boden-Albala B, Langa KM, Lisabeth LD, Fair M, Smith MA, et al. Projected costs of ischemic stroke in the United States. Neurology. 2006;67(8):1390–5. doi: 10.1212/01.wnl.0000237024.16438.20. Epub 2006/08/18. [DOI] [PubMed] [Google Scholar]
- 6.Ovbiagele B, Levine SR. Addressing racial and ethnic disparities in stroke: the time is now. Neurology. 2006;67(8):1328–9. doi: 10.1212/01.wnl.0000243251.36208.12. Epub 2006/10/25. [DOI] [PubMed] [Google Scholar]
- 7.Stansbury JP, Jia H, Williams LS, Vogel WB, Duncan PW. Ethnic disparities in stroke: epidemiology, acute care, and postacute outcomes. Stroke; a journal of cerebral circulation. 2005;36(2):374–86. doi: 10.1161/01.STR.0000153065.39325.fd. Epub 2005/01/08. [DOI] [PubMed] [Google Scholar]
- 8.Ayala C, Greenlund KJ, Croft JB, Keenan NL, Donehoo RS, Giles WH, et al. Racial/ethnic disparities in mortality by stroke subtype in the United States, 1995-1998. American journal of epidemiology. 2001;154(11):1057–63. doi: 10.1093/aje/154.11.1057. Epub 2001/11/29. [DOI] [PubMed] [Google Scholar]
- 9.Sacco RL, Boden-Albala B, Abel G, Lin IF, Elkind M, Hauser WA, et al. Race-ethnic disparities in the impact of stroke risk factors: the northern Manhattan stroke study. Stroke; a journal of cerebral circulation. 2001;32(8):1725–31. doi: 10.1161/01.str.32.8.1725. Epub 2001/08/04. [DOI] [PubMed] [Google Scholar]
- 10.Nguyen TV, Chandrashekar K, Qin Z, Parent AD, Zhang J. Epidemiology of intracranial aneurysms of Mississippi: a 10-year (1997-2007) retrospective study. Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2009;18(5):374–80. doi: 10.1016/j.jstrokecerebrovasdis.2008.12.004. Epub 2009/09/01. [DOI] [PubMed] [Google Scholar]
- 11.Keppel KG, Pearcy JN, Heron MP. Is there progress toward eliminating racial/ethnic disparities in the leading causes of death? Public Health Rep. 2010;125(5):689–97. doi: 10.1177/003335491012500511. Epub 2010/09/29. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Hanchate AD, Schwamm LH, Huang W, Hylek EM. Comparison of ischemic stroke outcomes and patient and hospital characteristics by race/ethnicity and socioeconomic status. Stroke; a journal of cerebral circulation. 2013;44(2):469–76. doi: 10.1161/STROKEAHA.112.669341. Epub 2013/01/12. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Kendall BE, Claveria LE. The use of computed axial tomography (CAT) for the diagnosis and management of intracranial angiomas. Neuroradiology. 1976;12(3):141–60. doi: 10.1007/BF00341859. Epub 1976/01/01. [DOI] [PubMed] [Google Scholar]
- 14.Cruz-Flores S, Rabinstein A, Biller J, Elkind MS, Griffith P, Gorelick PB, et al. Racial-ethnic disparities in stroke care: the American experience: a statement for healthcare professionals from the American Heart Association/American Stroke Association. Stroke; a journal of cerebral circulation. 2011;42(7):2091–116. doi: 10.1161/STR.0b013e3182213e24. Epub 2011/05/28. [DOI] [PubMed] [Google Scholar]
- 15.Trimble B, Morgenstern LB. Stroke in minorities. Neurol Clin. 2008;26(4):1177–90. doi: 10.1016/j.ncl.2008.05.010. xi. Epub 2008/11/26. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Boden-Albala B, Sacco RL, Lee HS, Grahame-Clarke C, Rundek T, Elkind MV, et al. Metabolic syndrome and ischemic stroke risk: Northern Manhattan Study. Stroke; a journal of cerebral circulation. 2008;39(1):30–5. doi: 10.1161/STROKEAHA.107.496588. Epub 2007/12/08. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Romano JG, Arauz A, Koch S, Dong C, Marquez JM, Artigas C, et al. Disparities in Stroke Type and Vascular Risk Factors Between 2 Hispanic Populations in Miami and Mexico City. Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2012 doi: 10.1016/j.jstrokecerebrovasdis.2012.05.016. Epub 2012/07/04. [DOI] [PubMed] [Google Scholar]
- 18.Crimmins EM, Kim JK, Alley DE, Karlamangla A, Seeman T. Hispanic paradox in biological risk profiles. Am J Public Health. 2007;97(7):1305–10. doi: 10.2105/AJPH.2006.091892. Epub 2007/06/01. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Waybright EA, Selhorst JB, Rosenblum WI, Suter CG. Blue rubber bleb nevus syndrome with CNS involvement and thrombosis of a vein of galen malformation. Ann Neurol. 1978;3(5):464–7. doi: 10.1002/ana.410030522. Epub 1978/05/01. [DOI] [PubMed] [Google Scholar]
- 20.Mottillo S, Filion KB, Genest J, Joseph L, Pilote L, Poirier P, et al. The metabolic syndrome and cardiovascular risk a systematic review and meta-analysis. J Am Coll Cardiol. 2010;56(14):1113–32. doi: 10.1016/j.jacc.2010.05.034. Epub 2010/09/25. [DOI] [PubMed] [Google Scholar]
- 21.Zimmerman RA, Bilaniuk LT. Computed tomography of choroid plexus lesions. J Comput Tomogr. 1979;3(2):93–103. doi: 10.1016/0149-936x(79)90001-8. Epub 1979/06/01. [DOI] [PubMed] [Google Scholar]
- 22.Morgenstern LB, Smith MA, Lisabeth LD, Risser JM, Uchino K, Garcia N, et al. Excess stroke in Mexican Americans compared with non-Hispanic Whites: the Brain Attack Surveillance in Corpus Christi Project. American journal of epidemiology. 2004;160(4):376–83. doi: 10.1093/aje/kwh225. Epub 2004/08/03. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Lisabeth LD, Smith MA, Brown DL, Moye LA, Risser JM, Morgenstern LB. Ethnic differences in stroke recurrence. Ann Neurol. 2006;60(4):469–75. doi: 10.1002/ana.20943. Epub 2006/08/24. [DOI] [PubMed] [Google Scholar]
- 24.Smith MA, Risser JM, Lisabeth LD, Moye LA, Morgenstern LB. Access to care, acculturation, and risk factors for stroke in Mexican Americans: the Brain Attack Surveillance in Corpus Christi (BASIC) project. Stroke; a journal of cerebral circulation. 2003;34(11):2671–5. doi: 10.1161/01.STR.0000096459.62826.1F. Epub 2003/10/25. [DOI] [PubMed] [Google Scholar]
- 25.Lisabeth LD, Smith MA, Brown DL, Uchino K, Morgenstern LB. Family history and stroke outcome in a bi-ethnic, population-based stroke surveillance study. BMC Neurol. 2005;5:20. doi: 10.1186/1471-2377-5-20. Epub 2005/11/03. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Curtis JP, Selter JG, Wang Y, Rathore SS, Jovin IS, Jadbabaie F, et al. The obesity paradox: body mass index and outcomes in patients with heart failure. Archives of internal medicine. 2005;165(1):55–61. doi: 10.1001/archinte.165.1.55. Epub 2005/01/12. [DOI] [PubMed] [Google Scholar]
- 27.Tseng CH. Obesity paradox: differential effects on cancer and noncancer mortality in patients with type 2 diabetes mellitus. Atherosclerosis. 2013;226(1):186–92. doi: 10.1016/j.atherosclerosis.2012.09.004. Epub 2012/10/09. [DOI] [PubMed] [Google Scholar]
- 28.Marques MB, Langouche L. Endocrine, metabolic, and morphologic alterations of adipose tissue during critical illness. Crit Care Med. 2013;41(1):317–25. doi: 10.1097/CCM.0b013e318265f21c. Epub 2012/11/09. [DOI] [PubMed] [Google Scholar]
- 29.Dixon JB, Lambert GW. The obesity paradox--a reality that requires explanation and clinical interpretation. Atherosclerosis. 2013;226(1):47–8. doi: 10.1016/j.atherosclerosis.2012.11.005. Epub 2012/12/12. [DOI] [PubMed] [Google Scholar]
- 30.Fonseca AC, Ferro JM. Drug abuse and stroke. Curr Neurol Neurosci Rep. 2013;13(2):325. doi: 10.1007/s11910-012-0325-0. Epub 2013/01/10. [DOI] [PubMed] [Google Scholar]
- 31.Rehm J, Gmel G, Sempos CT, Trevisan M. Alcohol-related morbidity and mortality. Alcohol Res Health. 2003;27(1):39–51. Epub 2004/08/11. [PMC free article] [PubMed] [Google Scholar]
- 32.Elkind MS, Sciacca R, Boden-Albala B, Rundek T, Paik MC, Sacco RL. Moderate alcohol consumption reduces risk of ischemic stroke: the Northern Manhattan Study. Stroke; a journal of cerebral circulation. 2006;37(1):13–9. doi: 10.1161/01.STR.0000195048.86810.5b. Epub 2005/11/25. [DOI] [PubMed] [Google Scholar]