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Biomedical subjects

R B Shekelle

Publications and source records attributed to R B Shekelle.

At least 19 recordsLinked to original sources
PubMed1992

Serum cholesterol, beta-carotene, and risk of lung cancer.

This paper hypothesizes that beta-carotene mediates the association between low serum cholesterol and increased risk of lung cancer, predicts that the association should be greater in population strata with low intake of beta-carotene than in those with high intake if the hypothesis is correct, and investigates this prediction with data from a 24-year cohort study of 1,960 middle-aged employed men. In the total cohort, serum cholesterol was not related to risk of lung cancer. The relative risk associated with a difference of -1.0 mmol per liter in serum cholesterol was 1.01 (95% confidence interval of 0.80-1.27) after adjustment for cigarette smoking, age, and intake of beta-carotene. In contrast, however, when the study group was restricted to men with intake of beta-carotene less than 5,000 (N = 929) or less than 3,000 IU per day (N = 272), comparable relative risks were 1.10 and 1.21, respectively. Although the 95% confidence intervals for these relative risks were broad and included unity, the result is consistent with expectation. We conclude that the hypothesis warrants further investigation.

Adult↗
PubMed1992

A delicate subject.

Explore the source record for details and available documents.

Epidemiologic Methods↗
PubMed1992

Does body fatness modify the association between dietary cholesterol and risk of coronary death? Results from the Chicago Western Electric Study.

The hypothesis that body fatness modifies the relation between dietary cholesterol and 25-year coronary mortality was examined in a cohort of 1,792 middle-aged men employed by the Western Electric Company in Chicago. Relative risks of coronary death (and 95% confidence intervals) associated with a 225 mg/day greater intake of dietary cholesterol for men with a subscapular skinfold thickness less than or equal to 14, 15-20, and greater than or equal to 21 mm were 1.44 (1.10-1.90), 1.07 (0.84-1.36), and 0.95 (0.76-1.20), respectively, after adjustment for age; serum total cholesterol level; systolic blood pressure; cigarette smoking; family history of cardiovascular disease; evidence of major organ system disease at baseline; and intake of saturated fatty acids, polyunsaturated fatty acids, energy, and ethanol. Adjusted relative risks associated with a 15-mm greater subscapular skinfold thickness for men with a dietary cholesterol intake less than or equal to 649, 650-799, and greater than or equal to 800 mg/day were 1.76 (1.04-2.98), 1.64 (1.04-2.57), and 1.00 (0.69-1.55), respectively. Fatter men apparently did not benefit from a diet lower in cholesterol, while men who ate a diet high in cholesterol apparently did not benefit from leanness. These results support the hypothesis that body fatness modifies the relation between dietary cholesterol and coronary mortality, perhaps because leaner men are more responsive than fatter men to the effects of dietary cholesterol on the concentration of low density lipoprotein cholesterol.

Adipose Tissue↗
PubMed1991

Dietary cholesterol and incidence of lung cancer: the Western Electric Study.

The hypothesis that dietary cholesterol is positively associated with lung cancer was investigated in a 24-year cohort study of 1,878 middle-aged men who were employed in 1958 by the Western Electric Company in Chicago. The relative risk of lung cancer associated with an increment in dietary cholesterol of 500 mg/day was 1.9 (95 percent confidence interval 1.1-3.4) after adjustment for cigarettes, age, and intake of beta-carotene and fat. Results suggested that the association was specific to cholesterol from eggs. Further research is needed to understand the basis for this association.

Adenocarcinoma↗
PubMed1990

Post-load plasma glucose and cancer mortality in middle-aged men and women. 12-year follow-up findings of the Chicago Heart Association Detection Project in Industry.

The relation of post-load plasma glucose to 12-year cancer mortality was studied in 11,521 white men and 8,591 white women aged 35-64 years at entry in the Chicago Heart Association Detection Project in Industry. There were 298 deaths in which cancer was the underlying cause in men and 186 such deaths in women. Plasma glucose levels at baseline measured one hour after a 50 g oral glucose load were positively related to cancer mortality in men but not in women. This increased mortality in men persisted after controlling for age, body mass index, smoking, serum cholesterol, systolic blood pressure, education, and anti-hypertensive treatment. A site-specific analysis of the male cancer deaths demonstrated higher mean plasma glucose levels for decedents for nearly all sites except oral cancers, liver cancer, and other respiratory cancers. For women, elevations existed for those who died of colon, lung, and hematologic/lymphatic tumors, but not for most other sites. The associations between baseline post-load plasma glucose levels and cancer mortality were similar for earlier and later cancer deaths, which indicates that incipient or occult neoplasm at baseline was not responsible for elevated glucose levels in men who subsequently died of cancer. Cancer mortality rates were also higher for those with a clinical diagnosis of diabetes than for those without, but the numbers of persons with diabetes were small as were the numbers of cancer deaths (19 in the men and 10 in the women).

Administration, Oral↗
PubMed1989

Dietary cholesterol and ischaemic heart disease.

In a cohort of 1824 middle-aged men followed for 25 years, intake of dietary cholesterol was associated with risk of death from ischaemic heart disease, from other cardiovascular diseases combined, from all cardiovascular diseases combined, and from all causes combined. The relative hazard of death from all cardiovascular diseases combined, associated with the difference between the mean of the first and fifth quintiles of cholesterol intake (a difference of 184 mg cholesterol/1000 kcal intake) was 1.46 (95% confidence interval 1.10-1.94) after adjustment for age, intake of other dietary lipids, and other coronary risk factors (including serum cholesterol). When stratified into three groups according to serum cholesterol (less than 220 mg/dl, 220-259 mg/dl, and 260 mg/dl or above), the corresponding relative hazards were 1.58, 1.50, and 1.41, respectively. These results are further evidence for the concepts that dietary cholesterol is atherogenic in man, and that the effect is partly independent of total serum cholesterol. They reinforce the recommendation that intake of dietary cholesterol should be low in people without overt hyperlipidaemia as well as those with raised serum cholesterol.

Adult↗
PubMed1989

Serum uric acid and 11.5-year mortality of middle-aged women: findings of the Chicago Heart Association Detection Project in Industry.

The relationships of serum uric acid to mortality from all causes, the cardiovascular diseases, and cancer were evaluated in 6797 white women age 35-64 years followed for an average of 11.5 years in the Chicago Heart Association Detection Project in Industry (CHA). Serum uric acid levels at baseline were strongly and significantly associated with all causes mortality in this cohort, with control for multiple risk factors and with exclusion of hypertensives on treatment. When the analysis was performed on age-specific groups 35-44, 45-54, and 55-64 years of age, the association was observed primarily in women in the oldest age group. All cardiovascular deaths, deaths due to coronary heart disease, and all cancer deaths were also associated with serum uric acid levels in the 55-64 year old group. The relationships persisted with control for multiple risk factors and with exclusion of treated hypertensives. A site-specific analysis of cancer deaths demonstrated elevations in mean serum uric acid levels for nearly all sites. Differences in mean serum uric acid levels between decedents and survivors tended to be largest in the first 5 years of follow-up for the cardiovascular deaths, but for cancer decedents they tended to be larger for subsequent years of follow-up. As an initial report on the association of serum uric acid and cancer in women in this age group, the results of this study require confirmation. Although hormonal influences may play a role, pathophysiologic mechanisms relating serum uric acid to mortality in white women aged 55-64 are currently unknown.

Adult↗
PubMed1989

Large fluctuations in body weight during young adulthood and twenty-five-year risk of coronary death in men.

The hypothesis that large fluctuations in weight during young adulthood are associated with increased risk of coronary heart disease was investigated by comparing the 25-year mortality of three groups of middle-aged men with distinctly different patterns of self-reported weight during young adulthood: 98 men who reported large gains and large losses, 133 who reported large gains and no losses, and 178 who reported no substantial change in weight. They were selected from a cohort of 2,107 men aged 40-56 years who participated in the Western Electric Study from 1957 through 1983. The 25-year crude risk of coronary death was 26% in the "gain and loss" group, 15% in the "gain only" group, 14% in the "no change" group, and 17% in the remaining 1,550 men. After adjustment for age and major coronary risk factors, the relative risk of coronary death in the gain and loss group as compared with the no change group was 2.0 (95% confidence interval 1.2-3.5). Risk of death from cancer was highest in the gain only group, and risk of death from all causes combined was lowest in the no change group. These results support the concept that large changes in weight during young adulthood increase the risk of coronary disease and of cancer.

Adult↗
PubMed1988

Major and minor electrocardiographic abnormalities and risk of death from coronary heart disease, cardiovascular diseases and all causes in men and women.

The independent contributions of baseline major and minor electrocardiographic (ECG) abnormalities to subsequent 11.5 year risk of death from coronary heart disease, all cardiovascular diseases and all causes were explored among 9,643 white men and 7,990 white women aged 40 to 64 years without definite prior coronary heart disease in the Chicago Heart Association Detection Project in Industry. At baseline, prevalence rates of major ECG abnormalities were higher in women than in men, with age-adjusted rates of 12.9 and 9.6% (p less than 0.01), respectively. Minor ECG abnormalities were more common in men than in women (7.3 versus 4.5%, p less than 0.01). Both major and minor ECG abnormalities were associated with an increased risk of death from coronary heart disease, all cardiovascular diseases and all causes. The strength of these associations was greater in men than in women. When baseline age, diastolic pressure, serum cholesterol, cigarettes smoked per day, diabetes and use of antihypertensive medication were taken into account, major abnormalities continued to be significantly related to each cause of death in both genders with much larger adjusted absolute excess risk and relative risk for men than for women. In multivariate analyses, minor ECG abnormalities contributed independently to risk of death in men, but not clearly so in women. The results indicate the independent association between ECG abnormalities and mortality from coronary heart disease, all cardiovascular diseases and all causes, with greater relative significance in middle-aged United States men than women.

Adult↗
PubMed1985

Dietary vitamin D and calcium and risk of colorectal cancer: a 19-year prospective study in men.

Mortality rates from colon cancer in the USA are highest in populations exposed to the least amounts of natural sunlight; differences in endogenous vitamin D production and calcium absorption could be responsible. To investigate this possibility, the association of dietary vitamin D and calcium with 19-year risk of colorectal cancer was examined in 1954 men who had completed detailed, 28-day dietary histories in the period 1957-59. Risk of colorectal cancer was inversely correlated with dietary vitamin D and calcium. In the quartiles of a combined index of dietary vitamin D and calcium, from lowest to highest, observed risks of colorectal cancer were 38.9, 24.5, 22.5, and 14.3/1000 population. This association remained significant after adjustment for age, daily cigarette consumption, body mass index, ethanol consumption, and percentage of calories obtained from fat.

Adult↗
PubMed1979

Racial patterns of heart rate in an employed adult population.

This study explored racial patterns of heart rate in a large population of employed Chicagoans: 39,665 adults screened in Chicago firms between late 1967 and early 1973. Of these, 30,876 were white or black adults age 18--64 with complete data, and not on drug therapy for hypertension. Mean heart rates of young black men and women were significantly lower than mean heart rates of young white men and women. This difference was not present for the age groups 35 and older. The difference was present in both smokers and non-smokers; in normotensives and in persons with elevated blood pressure; and could not be explained by differences in relative body weight. The difference persisted after simultaneous adjustment for differences in the mean values of systolic blood pressure, relative weight, serum cholesterol, post-loaded plasma glucose, and number of cigarettes smoked per day.

Adolescent↗
PubMed1979

Uric acid: a risk factor for coronary heart disease?

The association between serum uric acid and the prevalence of ECG abnormalities was analyzed for 24.997 employed men and women, white and black, age 18--64 years, from the Chicago Heart Association (CHA) Detection Project in Industry. In addition, the relationships between uric acid and 5-year mortality from all causes, from cardiovascular diseases (CVD), and from coronary heart disease (CHD) were analyzed for 7804 white men and women age 45--64 years from this study and 967 white men age 44--63 years from the Chicago People's Gas Company Study. For men, the association between uric acid and the prevalence of ECG abnormalities and with mortality appear to be secondary to associations between uric acid and other risk factors. For women, however, the associations could not be explained by other risk factors.

Arrhythmias, Cardiac↗
PubMed1979

Evaluation of an automated blood pressure measuring device intended for general public use.

Responding to Chicago newspaper reports, measurements of blood pressure by a publicly available, automated coin-operated device were compared with those of human observers using the standard cuff and auscultatory technique. One machine was examined in the laboratory, and eight others at randomly selected sites. Analysis of readings made on 100 persons in the laboratory and 227 in the field led to the following conclusions: 1) On the average, the machines measured fifth phase diastolic blood pressure at nearly the same level as did human observers; 2) The machines were more variable measuring systolic blood pressure with four differing from the average human reading by 1mm Hg or less, but two differing by 8mm Hg or more; 3) The agreement between machine-human pairs of readings was not as good as between human-human pairs, but the differences in level of agreement--both in determining the actual value and in categorizing the values as normal, borderline, or high--were small and have little practical importance; 4) Linear regression analyses of the relationship between simultaneously determined machine and human readings indicated that the average human-machine difference was the same over the range of pressures tested. Publicly available blood pressure measuring devices should be labeled concerning their purposes, capabilities, and limitations. Rules and regulations governing their use in the City of Chicago are being prepared by this city's Legal Department.

Blood Pressure Determination↗
PubMed1978

Public beliefs about causes and prevention of heart attacks.

Interviews with a probability sample of 617 adults in the Chicago area indicated widespread lack of information about major probable causes of heart attacks in persons younger than 60 years: 28% named cigarette smoking, 21% named high blood pressure, and 13% named cholesterol or fat in the diet or blood. Half did not name any of these risk factors, and only 1% named all three. Although three fourths believed that heart attacks are preventable, few named specific behaviors that would effectively reduce risk factors other than smoking. Sustained community-wide educational programs about reducing coronary risk factors are clearly needed and can be effective.

Adult↗
PubMed1978

The "false negative" treadmill exercise test and left ventricular dysfunction.

One hundred and fifteen consecutive symptomatic patients undergoing graded exercise testing, selective coronary angiography and left ventriculography were retrospectively evaluated. The sensitivity, specificity, and false negative response rates of the exercise tests were 79%, 81%, and 21%, respectively. Although the magnitude of a positive ST-segment response was related to more extensive vascular disease, the frequency of false negative responses was nearly identical in patients with single, double, or triple vessel disease (22%, 21%, 19%). Analysis of the false negative group demonstrated significant ventriculographic and hemodynamic abnormalities when compared to the true positive responders. Five out of six patients with the most serious motion disorders in the study fell into the false negative group. There were no significant differences in the extent, distribution and severity of vascular involvement, or in the development of collateral circulation in the two groups. However, occluded vessels supplied abnormal ventricular segments more frequently in the false negative group (88% vs 38%); the absence of an "ischemic response" and the presence of segments of abnormal myocardium may be related. Left ventricular dysfunction appears to be an important reason for a false negative response to exercise.

Angiography↗