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Biomedical subjects

A Ascherio

Publications and source records attributed to A Ascherio.

99 records · Page 6Linked to original sources
PubMed1993

A retrospective cohort study of vasectomy and prostate cancer in US men.

OBJECTIVE: To examine the relationship between vasectomy and prostate cancer. DESIGN: Retrospective cohort study. SETTING: Husbands of nurses in 11 large states in the United States. PARTICIPANTS: In questionnaires administered in 1976 and 1978, 14,607 married female participants of the Nurses' Health Study reported vasectomy as the couple's form of contraception. In 1989, we contacted these 14,607 women and 14,607 age-matched participants whose husbands had not had a vasectomy prior to 1978 to ascertain their husband's disease status between 1976 and 1989. MAIN OUTCOME MEASURE: Diagnosis of prostate cancer. RESULTS: During the study period, from 1976 through 1989, 96 new cases of prostate cancer were diagnosed in the cohort. Vasectomy was associated with an increased risk of prostate cancer (age-adjusted relative risk, 1.56; 95% confidence interval, 1.03 to 2.37; P = .04). The relative risk of prostate cancer increased over time since vasectomy. Among men who had their vasectomy 20 or more years in the past, the relative risk of prostate cancer was 1.89 (95% confidence interval, 1.14 to 3.14; P = .005), and after excluding stage A and B cases, the relative risk was 2.06 (95% confidence interval, 0.95 to 4.43; P = .07). This elevated risk of prostate cancer among vasectomized men persisted when we adjusted for smoking, alcohol consumption, educational level, body mass index, and geographical area of residence. CONCLUSIONS: These results support evidence from other epidemiologic studies that vasectomy increases risk of prostate cancer. A biological mechanism whereby vasectomy influences the rate of prostate cancer may be related to a diminished secretory rate of prostatic fluid following vasectomy, or, alternatively, to the postvasectomy immune response to sperm antigens, which may cross-react with tumor-associated antigens and suppress tumor immunosurveillance mechanisms.

Adult↗
PubMed1993

A prospective cohort study of vasectomy and prostate cancer in US men.

OBJECTIVE: To examine prospectively the relationship between vasectomy and prostate cancer. DESIGN: Cohort study. SETTING: Health professionals (dentists, veterinarians, osteopaths, optometrists, pharmacists, and podiastrists) in the United States. PARTICIPANTS: There were 10,055 male members of the Health Professionals Follow-up Study, aged 40 to 75 years, who had had a vasectomy, and 37,800 members who had not had a vasectomy at the time of study entry in 1986. These participants had provided detailed information on various life-style variables including diet. MAIN OUTCOME MEASURE: Diagnosis of prostate cancer. RESULTS: Between 1986 and 1990, 300 new cases of prostate cancer were diagnosed in participants who were initially free of diagnosed cancer. Vasectomy was associated with an elevated risk of prostate cancer (age-adjusted relative risk, 1.66; 95% confidence interval, 1.25 to 2.21; P = .0004). This elevated risk persisted after excluding 21 stage A1 cases (age-adjusted relative risk, 1.56; 95% confidence interval, 1.15 to 2.11; P = .004). Among men who had their vasectomy at least 22 years in the past (before 1965), the risk of prostate cancer was even higher (relative risk, 1.85; 95% confidence interval, 1.26 to 2.72; P = .002). This elevated risk among men with vasectomy did not appear to be caused by detection bias and persisted when we controlled for diet, level of physical activity, smoking, alcohol consumption, educational level, body mass index, and geographical area of residence. CONCLUSIONS: These results support evidence from other epidemiologic studies that vasectomy increases risk of prostate cancer. The consistency of results among various epidemiologic studies, the increase of risk over time following vasectomy, the apparent lack of confounding or bias, and the existence of physiological changes in the prostate following vasectomy suggest that the association may be causal.

Adult↗
PubMed1992

Effect of the Gulf War on infant and child mortality in Iraq.

BACKGROUND: Increased malnutrition and morbidity among Iraqi children after the onset of the Persian Gulf war have been reported by several fact-finding missions. The magnitude of the effect of the war and the economic embargo on child mortality remains uncertain, however. METHODS: We conducted a survey of 271 clusters of 25 to 30 households each, chosen as a representative sample of the Iraqi population. The households were selected and the interviews conducted by an international team of public health professionals independent of Iraqi authorities. In each household all women 15 to 49 years of age were interviewed, and the dates of birth and death of all children born on or after January 1, 1985, were recorded. RESULTS: The study population included 16,076 children, 768 of whom died during the period surveyed (January 1, 1985, to August 31, 1991). The age-adjusted relative mortality for the period after the war began, as compared with the period before the war, was 3.2 (95 percent confidence interval, 2.8 to 3.7). No material change in the relative risk was observed after adjustment for region of residence, maternal education, and maternal age. The increase in mortality after the onset of the war was higher among children 1 to less than 12 months old (relative risk, 4.1; 95 percent confidence interval, 3.3 to 5.2) and among those 12 to less than 60 months old (relative risk, 3.8; 95 percent confidence interval, 2.6 to 5.4) than among those less than 1 month old (relative risk, 1.8; 95 percent confidence interval, 1.4 to 2.4). The association between the war and mortality was stronger in northern Iraq (relative risk, 5.3) and southern Iraq (relative risk, 3.4) than in the central areas (relative risk, 1.9) or in Baghdad (relative risk, 1.7). CONCLUSIONS: These results provide strong evidence that the Gulf war and trade sanctions caused a threefold increase in mortality among Iraqi children under five years of age. We estimate that more than 46,900 children died between January and August 1991.

Child, Preschool↗
PubMed1992

Correlations of vitamin A and E intakes with the plasma concentrations of carotenoids and tocopherols among American men and women.

The authors investigated the association of diet and other factors with the plasma concentrations of carotenoids, retinol and tocopherols in a sample of 121 men and 186 women participating in two prospective investigations of dietary etiologies of chronic diseases. Lycopene (mean concentration, 0.82 mumol/L in men, 0.76 mumol/L in women), beta-carotene (mean 0.46 mumol/L in men, 0.58 mumol/L in women) and lutein (mean 0.28 mumol/L in men, 0.27 mumol/L in women) were the major circulating carotenoids. Among nonsmokers, dietary carotenoid, as typically calculated in epidemiologic studies, was significantly correlated with plasma beta-carotene (r = 0.34 in men, r = 0.30 in women), alpha-carotene (r = 0.52 in men, r = 0.37 in women) and lutein (r = 0.36 in men, r = 0.19 in women), but not with plasma zeaxanthin (r = 0.11 and r = 0.02) or lycopene (r = 0.13 and r = 0.01) after adjusting for plasma cholesterol and triglycerides, body mass index and energy intake. Total vitamin E intake was positively associated with plasma concentrations of alpha-tocopherol (r = 0.51 in men, r = 0.41 in women) and inversely associated with plasma concentrations of gamma-tocopherol (r = -0.51 in men r = -0.42 in women), but this was primarily due to use of vitamin E supplements. Measurements of specific carotenoids can provide independent information beyond the usual calculation of carotene intake in epidemiologic studies.

Carotenoids↗
PubMed1992

A prospective study of nutritional factors and hypertension among US men.

BACKGROUND: An effect of diet in determining blood pressure is suggested by epidemiological studies, but the role of specific nutrients is still unsettled. METHODS AND RESULTS: The relation of various nutritional factors with hypertension was examined prospectively among 30,681 predominantly white US male health professionals, 40-75 years old, without diagnosed hypertension. During 4 years of follow-up, 1,248 men reported a diagnosis of hypertension. Age, relative weight, and alcohol consumption were the strongest predictors for the development of hypertension. Dietary fiber, potassium, and magnesium were each significantly associated with lower risk of hypertension when considered individually and after adjustment for age, relative weight, alcohol consumption, and energy intake. When these nutrients were considered simultaneously, only dietary fiber had an independent inverse association with hypertension. For men with a fiber intake of < 12 g/day, the relative risk of hypertension was 1.57 (95% confidence interval, 1.20-2.05) compared with an intake of > 24 g/day. Calcium was significantly associated with lower risk of hypertension only in lean men. Dietary fiber, potassium, and magnesium were also inversely related to baseline systolic and diastolic blood pressure and to change in blood pressure during the follow-up among men who did not develop hypertension. Calcium was inversely associated with baseline blood pressure but not with change in blood pressure. No significant associations with hypertension were observed for sodium, total fat, or saturated, transunsaturated, and polyunsaturated fatty acids. Fruit fiber but not vegetable or cereal fiber was inversely associated with incidence of hypertension. CONCLUSIONS: These results support hypotheses that an increased intake of fiber and magnesium may contribute to the prevention of hypertension.

Adult↗
PubMed1991

Prospective study of alcohol consumption and risk of coronary disease in men.

Although an inverse association between alcohol consumption and risk of coronary artery disease has been consistently found in several types of studies, some have argued that the association is due at least partly to the inclusion in the non-drinking reference group of men who abstain because of pre-existing disease. The association between self-reported alcohol intake and coronary disease was studied prospectively among 51,529 male health professionals. In 1986 the participants completed questionnaires about food and alcohol intake and medical history, heart disease risk factors, and dietary changes in the previous 10 years. Follow-up questionnaires in 1988 sought information about newly diagnosed coronary disease. 350 confirmed cases of coronary disease occurred. After adjustment for coronary risk factors, including dietary intake of cholesterol, fat, and dietary fibre, increasing alcohol intake was inversely related to coronary disease incidence (p for trend less than 0.001). Exclusion of 10,302 current non-drinkers or 16,342 men with disorders potentially related to coronary disease (eg, hypertension, diabetes, and gout) which might have led men to reduce their alcohol intake, did not substantially affect the relative risks. These findings support the hypothesis that the inverse relation between alcohol consumption and risk of coronary disease is causal.

Adult↗
PubMed1991

Nutrient intakes and blood pressure in normotensive males.

The association of dietary intakes with blood pressure levels was examined in a cross-sectional sample of 805 men aged 40-69 years free from clinical hypertension, coronary heart disease or cancer. After controlling for age, body habitus, and alcohol consumption, blood pressure levels were inversely associated with the intake of fruit (r = -0.09, p less than 0.05, for both systolic (SBP) and diastolic (DBP) blood pressure) and of fruit fibre (r = -0.07, p = 0.05 for SBP; r = -0.07, p = 0.07 for DBP). This association was independent of the intake of minerals and fibre from other sources. Calcium and magnesium intake were not significantly associated with blood pressure levels, but our results are statistically compatible with the modest inverse associations previously reported. These cross-sectional data suggest that some component of fruit has a blood pressure lowering effect.

Adult↗
PubMed1990

Field evaluation of measles vaccine efficacy in Mozambique.

Monitoring measles vaccine efficacy is an important form of quality control in immunization programs. Retrospective cohort studies of vaccine efficacy were conducted in Mozambique with the aim of adopting this method for regular use. The authors studied 1,215 and 790 children aged 12-35 months in the cities of Nampula and Beira, respectively. In Nampula (1985), vaccine efficacy was estimated to be 40%, and in Beira (1986), it was estimated to be 59%. To investigate the possibility of falsely low results due to poor specificity of maternal reporting of measles cases, a seroepidemiologic study of 600 children aged 12-47 months was conducted in Nampula in 1986. The specificity and sensitivity of a maternal history of measles in an unvaccinated child were estimated as 83% and 56%, respectively. These results were used to obtain an adjusted vaccine efficacy estimate of 66%, almost double the estimate of 37% obtained using data on history of vaccination and illness alone. The large bias introduced into the vaccine efficacy estimation by low specificity of disease diagnosis is a serious limitation to the use of retrospective cohort methods to assess efficacy.

Child, Preschool↗