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Biomedical subjects

W H Giles

Publications and source records attributed to W H Giles.

At least 19 recordsLinked to original sources
PubMed1998

Platelet glycoprotein receptor IIIa polymorphism P1A2 and ischemic stroke risk: the Stroke Prevention in Young Women Study.

BACKGROUND AND PURPOSE: Platelet glycoprotein IIb/IIa (GpIIb-IIIa), a membrane receptor for fibrinogen and von Willebrand factor, has been implicated in the pathogenesis of acute coronary syndromes but has not been previously investigated in relation to stroke in young adults. METHODS: We used a population-based case-control design to examine the association of the GpIIIa polymorphism P1A2 with stroke in young women. Subjects were 65 cerebral infarction cases (18 patients with and 47 without an identified probable etiology) 15 to 44 years of age from the Baltimore-Washington region and 122 controls frequency matched by age from the same geographic area. A face-to-face interview for vascular disease risk factors and a blood sample for the P1A2 allele and serum cholesterol were obtained from each participant. Logistic regression was used to estimate the odds ratio for one or more P1A2 alleles after adjustment for other risk factors. RESULTS: Among cases and controls, the prevalence rates of one or more P1A2 alleles were 21% and 22% among blacks and 36% and 28% among whites, respectively. This genotype was significantly associated with hypertension only in black control subjects but otherwise not with any of the established vascular risk factors. The adjusted odds ratio for cerebral infarction of one or more P1A2 alleles was 1.1 (confidence interval [CI], 0.6 to 2.3) overall, 0.5 (CI, 0.1 to 7.1) among blacks, and 1.4 (CI, 0.5 to 3.7) among whites. For the cases with an identified probable etiology, the corresponding odds ratios were 3.0 (CI, 0.9 to 10.4) overall, 0.7 (CI, 0.1 to 7.1) among blacks, and 12.8 (CI, 1.2 to 135.0) among whites. CONCLUSIONS: No association was found between the P1A2 polymorphism of GpIIIa and young women with stroke. However, subgroup analyses showed that the P1A2 polymorphism of GpIIIa appeared to be associated with stroke risk among white women, particularly those with a clinically identified probable etiology for their stroke. Further work with an emphasis on stroke subtypes and with multiracial populations is warranted.

Adolescent↗
PubMed1998

Impaired glucose tolerance and the likelihood of nonfatal stroke and myocardial infarction: the Third National Health and Nutrition Examination Survey.

BACKGROUND AND PURPOSE: Although diabetes mellitus (DM) is known to increase the risk of cardiovascular disease (CVD), the effect of impaired glucose tolerance (IGT) on the risk remains unclear. We determined whether IGT was associated with an increased likelihood for stroke and myocardial infarction in a nationally representative sample of US adults. METHODS: We evaluated the association between IGT (defined as a fasting glucose level of < 140 mg/dL and a plasma glucose level of between 140 and 200 mg/dL 2 hours after administration of 75 grams of an oral glucose load) and DM (defined as the current use of insulin or an oral hypoglycemic medication, a fasting plasma glucose level of > 140 mg/dL, or a plasma glucose level of > 200 mg/dL 2 hours after administration of an oral glucose load) with a self-reported physician diagnosis of stroke and myocardial infarction in 6547 adults aged 40 to 74 years participating in the Third National Health and Nutrition Examination Survey. Multivariate logistic regression analyses were used to investigate these relationships. RESULTS: IGT and DM were observed in 1494 and 1532 adults, respectively. After adjustment for differences in age, gender, race/ethnicity, education, hypertension, cholesterol, body mass index, and cigarette smoking, IGT was not associated with stroke (odds ratio [OR], 0.9; 95% confidence interval [CI], 0.5 to 1.6) or myocardial infarction (OR, 1.1; 95% CI, 0.7 to 1.6). DM was associated with both stroke (OR, 1.6; 95% CI, 1.0 to 2.6) and myocardial infarction (OR, 1.9; 95% CI, 1.3 to 2.8). CONCLUSIONS: In contrast to DM, IGT was not associated with an increased likelihood of prevalent nonfatal stroke or myocardial infarction.

Adult↗
PubMed1998

Thermolabile methylenetetrahydrofolate reductase polymorphism (C677T) and total homocysteine concentration among African-American and white women.

A polymorphism associated with a thermolabile variant (C677T) of the enzyme methylenetetrahydrofolate reductase has been associated with both elevated total homocysteine (tHcy) levels and risk for cardiovascular disease. Data from the Stroke Prevention in Young Women Study were used to determine the prevalence of the C677T genotype and to assess whether environmental factors modified the association between genotype and tHcy concentration. The C677T genotype prevalence was 80% -/-, 20% +/-, and 0% +/+ among 46 African-American women; and 39% -/-, 53% +/-, and 8% +/+ among 77 white women (P < 0.01). There was a trend toward higher tHcy levels in African-American women with the +/- genotype when compared with the -/- genotype (6.9 mumol/L vs 5.3 mumol/L respectively, p = 0.10); no association was found among the white women (6.0 mumol/L, -/-; 4.5 mumol/L, +/-; and 6.2 mumol/L, +/+; p = 0.67). Among African American women, those who smoked and were +/- genotype had the highest tHcy levels (8.0 mumol/L); while among white women, those who smoked and were -/- had the highest tHcy levels (8.1 mumol/L). Despite being hampered by a limited sample size, the thermolabile allele is significantly less common among African-American than white women. The association between genotype and tHcy concentration is influenced by smoking and multivitamin use.

Adolescent↗
PubMed1997

Number of pregnancies and risk for stroke and stroke subtypes.

OBJECTIVE: To examine the effect of the number of pregnancies on the subsequent risk for stroke and stroke subtypes. DESIGN: Prospective cohort study. PARTICIPANTS: National cohort of 3852 women aged 45 to 74 years who participated in the first National Health and Nutrition Examination Survey Epidemiology Follow-up Study. MAIN OUTCOME MEASURES: Stroke, cerebral infarction, and intracerebral hemorrhage during a 20-year follow-up period. RESULTS: After adjusting for differences in age, women with 6 or more pregnancies were at an increased risk for any type of stroke (relative risk [RR] = 1.7; 95% confidence interval [CI], 1.2-2.3) and cerebral infarction (RR = 1.6; 95% CI, 1.2-2.3). Adjustment for stroke risk factors explained some but not all of the risk associated with pregnancy (RR = 1.3; 95% CI, 0.9-1.9 for all stroke, and RR = 1.3; 95% CI, 0.9-1.9 for cerebral infarction). The rate of intracerebral hemorrhage was 3-fold higher among women who had been pregnant when compared with nulligravida women; however, this finding did not reach statistical significance possibly because of the small number of intracerebral hemorrhages (n = 33). CONCLUSION: The number of pregnancies may influence the risk for stroke, particularly cerebral infarction, in women.

Aged↗
PubMed1997

Social class and race disparities in premature stroke mortality among men in North Carolina.

The purpose of this work was to examine the association between social class and premature stroke mortality among blacks and whites. For black men and white men in North Carolina, aged 35-54 years, mortality data from vital statistics files and population data from Census Public Use Microdata Sample files were matched according to social class for the years 1984-1993. Four categories of social class were defined based upon a two-dimensional classification scheme of occupations. For each category of social class, race-specific age-adjusted stroke mortality rates were calculated, and race-specific prevalences of income, wealth, education, unemployment, and disability were estimated. Women were excluded because comparable information on social class was not available from the mortality and population data sources. For both black men and white men, the highest rates of premature stroke mortality were observed among the lowest social classes. The rate ratios (RR) between the lowest and highest social class were 2.8 for black men and 2.3 for white men. Within each social class, black men had substantially higher rates of premature stroke mortality than white men (black-to-white RR ranged from 4.0 to 4.9). Among both black men and white men, the highest social class consistently had the most favorable levels of income, wealth, education, and employment. The inverse association between social class and stroke mortality for both black men and white men supports the need for stroke prevention efforts that address the structural inequalities in economic and social conditions.

Adult↗
PubMed1997

Major depression and all-cause mortality among white adults in the United States.

PURPOSE: Depression is the most common psychiatric illness affecting adults. Despite the importance of a potential link between major depression and mortality, research has been surprisingly sparse. METHODS: Information on 57,897 white adults aged 25 years and older who were included in the mental health supplement of the 1989 National Health Interview Survey was linked with the National Death Index to examine the relationship of major depression to mortality. Death status was obtained through December 1991. Sex-specific hazard rate ratios for mortality were calculated by Cox proportional hazards regression and Poisson regression to adjust for potential confounders (age, education, marital status, body mass index, and whether the target subject or a family member completed the survey about the subject). RESULTS: Major depression was reported for 223 (0.8%) of 27,345 men and 392 (1.3%) of 30,552 women. During the 2.5-year follow-up, death certificate data were obtained for 848 (3.1%) men and 651 (2.1%) women. The adjusted hazard rate ratios for all-cause mortality associated with major depression were 3.1 (95% confidence interval; 2.0-4.9) for men and 1.7 (95% confidence interval; 0.9-3.1) for women. CONCLUSIONS: These results suggest that major depression increases risk of all-cause mortality, particularly among men. Further research is needed to explain the mechanism.

Adult↗
PubMed1997

Effect of body mass index on activity limitation and mortality among older women: the National Health Interview Survey, 1986-1990.

We assessed the impact of body mass on the association between activity limitations due to chronic conditions and mortality among 24,612 noninstitutionalized white or African American women aged > or = 65 years who participated in a National Health Interview Survey between 1986 and 1990. We found that more African American women had activity limitations than white women (59% vs 46%, respectively). The difference by race was greatest (19% vs 10%) for the most severe limitation (unable to perform the major activity). For women aged 65-69, the major activity was working or keeping house; for those aged > or = 70, it was the ability to live independently. For white women in all three categories of body mass index (BMI) and for African American women with BMI 15%-85%, the risk of dying was significantly higher for those unable to perform the major activity than for those with no limitations, controlling for the effects of education, marital status, and perceived health. The findings confirm the established link between low BMI and mortality and between activity limitations and mortality. Additionally, the findings further suggest that activity limitations linked to chronic conditions increase the risk of death within each stratum of BMI after adjusting for potential confounders.

Activities of Daily Living↗
PubMed1997

Pharmacologic and dietary therapies in epilepsy: conventional treatments and recent advances.

A number of treatment options are currently available for the medical management of epilepsy. Conventional antiepileptic drugs (AEDs) include phenytoin, carbamazepine, valproic acid, ethosuximide, barbiturates, and benzodiazepines. Although these drugs control seizures, they may also cause blood dyscrasias, sedation, and cognitive impairment. Felbamate, gabapentin, lamotrigine, and vigabatrin are new AEDs believed to cause fewer side effects than conventional medications. Felbamate, however, has been linked with substantially increased incidence of aplastic anemia, and the other new AEDs have been studied for relatively short periods of time. Ketogenic diets, comprised of foods high in fat and low in protein and carbohydrate content, have been reported to improve seizure control. However, these diets are widely acknowledged to be unpalatable, making sustained compliance with dietary restrictions difficult. To promote long-term control of seizures, physicians must consider the side effects of therapeutic interventions for epilepsy, as well as their anticonvulsant efficacy.

Acetates↗
PubMed1997

National trends in the initial hospitalization for heart failure.

OBJECTIVES: Heart failure is a major health care burden among older adults, but information on recent trends has not been available. We compare rates, sociodemographic characteristics, and discharge outcomes of the initial hospitalization for heart failure in the Medicare populations of 1986 and 1993. DESIGN: Information reported on the Medicare hospital claims record during initial hospitalization for heart failure was compared for patients aged 65 and older hospitalized in 1986 (N = 631,306) and those aged 65 and older hospitalized in 1993 (N = 803,506). RESULTS: Age-standardized hospitalization rates (per 1000 person-years) for any diagnosis of heart failure were higher in 1993 than in 1986 (white: 24.6 vs 22.4, black: 26.1 vs 22.4, respectively). Age-specific results suggested an earlier onset of heart failure in black adults. In 1993, compared with 1986, higher proportions of heart failure patients were discharged to another care facility (white: 23.9% vs 16.8%, black: 17.6% vs 10.5%, respectively) or to health service care at home (white: 11.3% vs 6.0%, black: 12.4% vs 6.5%, respectively). In contrast, in-hospital mortality was lower in 1993 than in 1986 (white: 10.4% vs 13.3%, black: 8.9% vs 11.1%, respectively). CONCLUSION: The increased numbers of hospitalizations for heart failure and the likelihood that these patients will require advanced nursing care after discharge have important implications for future national health care expenditures and resources.

Age Distribution↗
PubMed1997

Habitual sleep patterns and risk for stroke and coronary heart disease: a 10-year follow-up from NHANES I.

BACKGROUND: Habitual sleep patterns may independently affect morbidity and mortality. However, the effect of habitual sleep patterns on the risk for stroke and coronary heart disease is unclear. METHODS: We evaluated the association between sleep duration and daytime somnolence (often or almost always taking daytime naps) with the incidence of stroke and coronary heart disease in a national cohort of 7,844 adults who participated in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. Cox proportional hazards analyses were used to examine these relationships during the 10-year follow-up. RESULTS: After adjusting for differences in age, race, gender, education, cigarette smoking, body mass index, serum cholesterol, systolic blood pressure, and diabetes mellitus, the risk for stroke was increased in persons who reported sleeping greater than 8 hours at night compared with persons who slept between 6 and 8 hours (relative risk [RR] = 1.5, 95% confidence interval [CI] = 1.1 to 2.0). Daytime somnolence was also associated with stroke incidence (RR = 1.4, 95% CI = 1.1 to 1.8). Persons who reported both greater than 8 hours of sleep and daytime somnolence were at the greatest risk for stroke (RR = 1.9, 95% CI = 1.2 to 3.1). Similar results were also found for coronary heart disease, although the results did not reach statistical significance in the multivariate adjusted model. CONCLUSIONS: Habitual sleep patterns have significant effects on the risk for stroke.

Adult↗
PubMed1997

Pharmacologic management of heart failure among older adults by office-based physicians in the United States.

BACKGROUND: Despite the recent availability of new classes of heart failure medications, little is known about national patterns in the actual physician utilization of these drugs. METHODS: In the National Ambulatory Medical Care Survey, 2912 US physicians reported on 16,968 office visits in 1991-1992 with patients aged > or = 65 years. National estimates were obtained from weighted results that accounted for the complex sampling design. RESULTS: An estimated 8.3 million (2.6%) office visits with older adults involved heart failure. This included 9.3% of visits to cardiologists, 4.3% to internists, 3.5% to general and family physicians, and 0.6% to other physicians. The most frequently prescribed medications during visits with these patients were diuretics (69%), digitalis compounds (46%), angiotensin-converting enzyme inhibitors (30%), and nitrates (19%). Internists and general and family physicians prescribed angiotensin-converting enzyme inhibitors, digitalis compounds, and loop diuretics for patients with heart failure less often than did cardiologists. CONCLUSIONS: These are the first national surveillance estimates of physician practices in the management of heart failure. These data were collected during the same period in which heart failure clinical trial results were initially published, and they provide a baseline for monitoring the influence of recent clinical practice guidelines and professional education on changes in the management of heart failure by primary care physicians.

Aged↗
PubMed1996

Leisure-time physical activity among older adults. United States, 1990.

OBJECTIVE: To investigate the prevalence and selected correlates of leisure-time physical activity in a nationally representative sample of persons aged 65 years or older. METHODS: Data from 2783 older male and 5018 older female respondents to the 1990 National Health Interview Survey were used. Regular physical activity was defined as participation in leisure-time physical activities 3 times or more per week for 30 minutes or more during the previous 2 weeks. Odds ratios (ORs) were estimated from multivariate logistic regression analysis. RESULTS: Prevalence of regular physical activity was 37% among older men and 24% among older women. Correlates of regular physical activity included the perception of excellent to good health (men: OR, 1.5; 95% confidence interval [CI], 1.1-1.9; women: OR, 1.6; 95% CI, 1.3-1.9), correct exercise knowledge (men: OR, 2.4; 95% CI, 1.9-3.1; women: OR, 2.7; 95% CI, 2.2-3.4), no activity limitations (men: OR, 1.3; 95% CI, 1.0-1.6; women: OR, 1.7; 95% CI, 1.4-2.0) and not perceiving "a lot" of stress during the previous 2 weeks (men: OR, 1.7; 95% CI, 1.2-2.4; women: OR, 1.3; 95% CI, 1.0-1.6). Among those who had been told at least twice that they had high blood pressure, physician's advice to exercise was associated with regular physical activity (men: OR, 1.6; 95% CI, 1.2-2.3; women: OR, 1.5; 95% CI, 1.2-1.9). The 2 major activities among active older adults were walking (men, 69%; women, 75%) and gardening (men, 45%; women, 35%). CONCLUSIONS: Prevalence of regular physical activity is low among older Americans. Identifying the correlates of physical activity will help to formulate strategies to increase physical activity in this age group.

Adult↗
PubMed1996

Cognitive functioning and posttraumatic stress disorder.

OBJECTIVE: The authors examined the association of cognitive impairment with posttraumatic stress disorder (PTSD) and other psychiatric diagnoses known to affect cognitive functioning. METHOD: The results of standardized neuropsychological tests were compared in four groups of Vietnam veterans: veterans with both a lifetime history of PTSD and a current diagnosis of depression, anxiety, or substance abuse; veterans with only a PTSD diagnosis; veterans with only a current diagnosis of depression, anxiety, or substance abuse; and veterans with none of these diagnoses. RESULTS: Veterans with both PTSD and concurrent diagnoses. exhibited more impairment in cognitive functioning than did veterans without these diagnoses. CONCLUSIONS: Cognitive deficits seen among persons diagnosed with PTSD may be associated with their concomitant diagnoses.

Adult↗
PubMed1996

Trends in mortality and health behaviors: status of white and African-American women.

A substantial proportion of mortality in the United States can be attributed to three major behaviors: using tobacco, maintaining an unhealthy diet, and being physically inactive. Using data from the South Carolina mortality files and Behavioral Risk Factor Surveillance System we were able to document state trends in mortality, cigarette smoking, physical inactivity, and unhealthy dietary practices. We found that, in spite of the declines in heart disease and stroke mortality noted nationally and in the state, the risk factor profiles for most women in South Carolina did not improve. This analysis further suggests that physical inactivity and dietary issues (excess caloric intake, low fruit and vegetable consumption) would be good choices for lifestyle interventions among women in South Carolina, not only because they ultimately affect mortality, but also because they exert interim effects on morbidity, including physical functioning and independence.

Black or African American↗
PubMed1995

Determinants of black-white differences in the risk of cerebral infarction. The National Health and Nutrition Examination Survey Epidemiologic Follow-up Study.

OBJECTIVE: To determine whether blacks in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study remained at increased risk for cerebral infarction after adjusting for stroke risk factors and sociodemographic factors. METHODS: A cohort study involving 8203 whites and 1362 blacks who participated in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. During the 13-year follow-up, 538 and 122 cerebral infarctions occurred in whites and blacks, respectively. RESULTS: The black-white risk for cerebral infarction varied by age (P = .007 for race-age interaction). Compared with whites of the same age, blacks aged 35 to 44 years were at significantly increased risk for cerebral infarction (relative risk, 2.62; 95% confidence interval, 1.23 to 5.57), while older blacks, those older than 64 years, were not at increased risk (relative risk, 1.14; 95% confidence interval, 0.90 to 1.46). The relative risk for cerebral infarction decreased to 2.07 (95% confidence interval, 0.97 to 4.42) in younger blacks and 0.82 (95% confidence interval, 0.29 to 2.33) in older blacks after adjustment for age, sex, education, history of heart disease, diabetes, systolic blood pressure, treatment for hypertension, Quetelet index, and serum hemoglobin and magnesium levels. CONCLUSIONS: These results indicate that much of the increased risk for cerebral infarction experienced by blacks can be explained by their higher prevalence of stroke risk factors, especially diabetes, hypertension, and lower educational attainment. Younger blacks, however, may still be at increased risk after adjusting for stroke risk factors.

Adult↗
PubMed1995

Race and sex differences in rates of invasive cardiac procedures in US hospitals. Data from the National Hospital Discharge Survey.

BACKGROUND: Lower rates of invasive cardiac procedures have been reported for blacks and women than for white men. However, few studies have adjusted for differences in the type of hospital of admission, insurance status, and disease severity. SETTING, DESIGN, AND PARTICIPANTS: Data from the National Hospital Discharge Survey were used to investigate race and sex differences in rates of cardiac catheterization, percutaneous transluminal coronary angioplasty, and coronary artery bypass surgery among 10,348 persons hospitalized for acute myocardial infarction. RESULTS: White men consistently had the highest procedure rates, followed by white women, black men, and black women. After matching for the hospital of admission and adjusting for age, in-hospital mortality, health insurance, and hospital transfer rates (with white men as the referent), the odds ratios for cardiac catheterization were 0.67 (95% confidence interval [CI], 0.51 to 0.87) for black men, 0.72 (95% CI, 0.63 to 0.83) for white women, and 0.50 (95% CI, 0.37 to 0.68) for black women. Similar race-sex differences were noted for percutaneous transluminal coronary angioplasty and coronary artery bypass surgery. CONCLUSIONS: Race and sex differentials in the rates of invasive cardiac procedures remained despite matching for the hospital of admission and controlling for other factors that influence procedure rates, suggesting that the race and sex of the patient influence the use of these procedures.

Adult↗
PubMed1995

Serum folate and risk for ischemic stroke. First National Health and Nutrition Examination Survey epidemiologic follow-up study.

BACKGROUND AND PURPOSE: A serum folate concentration < or = 9.2 nmol/L has been associated with elevated levels of plasma homocyst(e)ine. Elevated homocyst(e)ine levels have been associated with ischemic stroke in case-control studies; however, the results from prospective studies have been equivocal. We investigated whether a folate concentration < or = 9.2 nmol/L was associated with ischemic stroke in a national cohort. METHODS: We used data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study (n = 2006). Cox proportional hazards analyses were used to adjust for differences in follow-up time and covariates. During the 13-year follow-up, 98 ischemic strokes occurred. RESULTS: After adjusting for age, race, sex, education, diabetes, history of heart disease, systolic blood pressure, body mass index, hemoglobin level, cigarette smoking, and alcohol intake, participants with a folate concentration < or = 9.2 nmol/L were at slightly increased risk for ischemic stroke (relative risk [RR], 1.37; 95% confidence interval [CI], 0.82 to 2.29). There was a folate-race interaction (P = .11 for interaction term). Whites with a folate concentration < or = 9.2 nmol/L had a relative risk of 1.18 (95% CI, 0.67 to 2.08), whereas blacks had a relative risk of 3.60 (95% CI, 1.02 to 12.71). CONCLUSIONS: These findings suggest that a folate concentration < or = 9.2 nmol/L may be a risk factor for ischemic stroke, especially in blacks. However, given the small number of stroke events, additional studies are needed to assess the role of folate in the epidemiology of ischemic stroke.

Adult↗