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Biomedical subjects

A R Dyer

Publications and source records attributed to A R Dyer.

At least 19 recordsLinked to original sources
PubMed1992

Random digit dialing in Chicago CARDIA: comparison of individuals with unlisted and listed telephone numbers.

Young adult blacks and whites aged 18-30 years of both low and high educational levels were recruited through random digit dialing to participate in the Chicago, Illinois, portion of a longitudinal study, Coronary Artery Risk Development in Young Adults (CARDIA). Overall, 31% of randomly selected persons eligible to participate had unlisted telephone numbers--about 50% of black men and women and 11% and 17% of white men and women, respectively. There was no difference in proportions of numbers unlisted by educational level, except for white men, who were more likely to have unlisted numbers at a low educational level than at a high educational level. There was no consistent pattern of differences in rates of participation across race, sex, or education subgroups for unlisted and listed numbers, and there were no significant differences for selected health measures, except smoking. The findings suggest that in Chicago, there is a potential bias in estimates of sociodemographic characteristics from the exclusion of unlisted numbers, but it is likely to be insignificant if recruitment is stratified according to race, sex, and education. Within strata, there was little bias with respect to the attributes measured. Ideally, to guard against possible bias, random digit dialing is recommended as the preferred way to select a representative population-based sample.

Adolescent↗
PubMed1992

Distributed data analysis in a multicenter study: the CARDIA Study.

Unlike distributed data entry, which is used in many large epidemiologic studies and multicenter clinical trials, distributed data analysis is a relatively new concept. This paper reports on the usefulness of such a system in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. CARDIA distributes the entire examination dataset to participating centers soon after completion of each round of data collection. The process was designed to encourage more numerous, diverse, and rapid publications, and to allow for more efficient use of the manpower and expertise in centers. Responsibilities of the coordinating center have changed from a conventional coordinating center but remain substantial due to the need for collating, monitoring, verifying, and documenting the distributed data analysis (DDA) system. DDA is successful from the standpoint of implementation and operation--21 manuscripts representing work analyzed at six participating centers had been submitted for publication within 3.5 years of the completion of the baseline examination.

Adolescent↗
PubMed1991

Sister chromatid exchange analysis of human cells exposed to diagnostic levels of ultrasound.

Lymphocyte and lymphoblastoid cells were exposed in vitro to diagnostic levels of ultrasonic beams delivered by a Hewlett-Packard CE 30001 and a GE system with a 5 MHz linear transducer for 20 sec, 1 min, 5 min, and 20 min. Temperature and cavitation effects were controlled and there were matched sham exposures. The synergistic effects of theophylline with ultrasonography also were investigated. Small increases in sister chromatid exchange levels were observed after ultrasonic exposure, but increases were so small as to be unlikely to have clinical relevance. Theophylline was found to have no effect and ultrasonography had no effect on cell viability.

Adult↗
PubMed1990

Alcohol intake and blood pressure in young adults: the CARDIA Study.

Associations between self-reported average daily alcohol intake and blood pressure were assessed in 5031 black and white men and women ages 18-30 from the Coronary Artery Risk Development in Young Adults Study (CARDIA). In general, intake was positively but weakly related to both systolic and diastolic blood pressure. Associations with systolic pressure were generally stronger than those with diastolic pressure. With average daily alcohol intake categorized as none, 0.1-9.9 ml, 10.0-19.9 ml, 20.0-29.9 ml, and 30.0+ ml, mean systolic pressure, adjusted for age, body mass index, education, smoking, and physical activity, increased progressively with increasing intake in black and white men and in white women. Mean diastolic pressure increased progressively with increasing intake only in white men and women, but was highest for those averaging 30.0+ ml per day in black women as well as white men and women. Mean pressures were also compared for those averaging 75.0+ ml per day (men) or 50.0+ ml per day (women) vs those reporting no intake. Differences in adjusted mean pressures for white men were 3.2 mmHg (95% confidence limits (CL) -0.3, 6.8) for systolic pressure and 1.7 mmHg (-1.6, 5.0) for diastolic pressure. In black men differences were 4.4 mmHg (1.4, 7.4) and 3.4 mmHg (0.6, 6.3), respectively. Differences in white women were 1.4 mmHg (-2.5, 5.3) for systolic pressure and 0.9 mmHg (-2.7, 4.5) for diastolic pressure and for black women, -0.2 mmHg (-4.3, 3.8) and 1.9 mmHg (-1.9, 5.8). Separate analyses in smokers and nonsmokers of the associations between alcohol intake and blood pressure suggested that associations may differ by smoking status in some sex-race groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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↗
PubMed1990

Body mass index versus height and weight in relation to blood pressure. Findings for the 10,079 persons in the INTERSALT Study.

In INTERSALT, an international study of electrolytes and blood pressure, body mass index (kg/m2) was found to relate independently to blood pressure. These relations were assessed in 10,079 men and women aged 20-59 years from 52 centers around the world, based on a standardized protocol, central training of observers, a central laboratory, and extensive quality control. The purpose of the present analyses was to determine whether weight, directly adjusted for height, related to blood pressure as strongly as did body mass index. For all men and women combined, with adjustment for age, sex, alcohol intake, smoking, and sodium and potassium excretion in addition to height, the partial correlations of blood pressure with weight were 0.221 for systolic blood pressure and 0.238 for diastolic blood pressure. These values were slightly larger than the partial correlations for body mass index with blood pressure, which were 0.215 and 0.229, respectively. Although the regression coefficients for body mass index with systolic pressure had been larger in men than in women, suggesting a stronger association of systolic pressure with weight in men, the models with weight directly adjusted for height indicated that the difference in systolic pressure associated with a 10-kg difference in weight was 3.0 mmHg in both men and women. The corresponding weight-associated diastolic pressure differences ranged from 2.00 mmHg in women aged 40-59 years to 2.7 mmHg in men aged 20-39. In addition, with control for weight, height had a significant inverse association with blood pressure. The results of these analyses support the use of weight, with direct adjustment for height, as a useful and practical substitute for body mass index in analyses of the association of adiposity with blood pressure.

Adult↗
PubMed1990

Prerandomization: an alternative to classic randomization. The effects on recruitment in a controlled trial of arthroscopy for osteoarthrosis of the knee.

Possibly the greatest threat to the success of a randomized clinical trial is the inability to recruit an adequate number of subjects. Concern that the randomized clinical trial will adversely affect the physician-patient relationship is the most common reason for physicians' reluctance to enroll patients in such trials. We report a modification of a prerandomized design, first described by Zelen, which was implemented in a randomized clinical trial of arthroscopy for patients who had osteoarthrosis of the knee. The method was associated with a sixfold increase in the rate of accrual of patients as compared with the use of a classic randomization trial. We propose the design as a potential solution to the problem of recruitment of subjects, particularly for clinical studies.

Arthroscopy↗
PubMed1989

Primary prevention of hypertension by nutritional-hygienic means. Final report of a randomized, controlled trial.

A 5-year trial involving 201 men and women with high-normal blood pressure at baseline demonstrated the ability to reduce the incidence of hypertension in participants randomized to nutritional-hygienic intervention compared with a control group. The incidence of hypertension was 8.8% among 102 intervention group participants vs 19.2% among 99 control group members. The odds ratio for the incidence of hypertension in the control group was 2.4. Mean trial blood pressure also was lower in the intervention compared with the control group (-1.2 and -1.9 mm Hg, respectively, for diastolic blood pressure at work-site and office visits and -1.3 and -2.0 mm Hg, respectively, for systolic blood pressure at the two sites). Net weight loss in the intervention group averaged 2.7 kg during the trial; sodium intake was reduced by 25% and reported alcohol intake decreased by 30%. The majority of intervention participants also reported an increase in physical activity. Effect on blood pressure was related particularly to degree of weight loss. Results indicate that even a moderate reduction in risk factors for hypertension among hypertension-prone individuals contributes to the primary prevention of the disease.

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

Validity of reported pain as a measure of clinical state in juvenile rheumatoid arthritis.

Reported pain is one valid indicator of clinical state which should be used in the assessment and management of children with juvenile rheumatoid arthritis. Parents' reports of children's pain for 101 children with juvenile rheumatoid arthritis differed significantly by type of juvenile rheumatoid arthritis. When multiple regression was used separately for pauciarticular and polyarticular classifications of juvenile rheumatoid arthritis a measure of clinical state, which reflected joint activity, morning stiffness, and overall disease activity as rated by the doctor, had a significant and independent effect upon pain reported by parents. The child's age was not significantly related to the pain reported by parents. Children's pain reports did not differ significantly between older and younger children.

Adolescent↗
PubMed1989

Blood pressure in four remote populations in the INTERSALT Study.

Four remote population samples (Yanomamo and Xingu Indians of Brazil and rural populations in Kenya and Papua New Guinea) had the lowest average blood pressures among all 52 populations studied in INTERSALT, an international cooperative investigation of electrolytes and blood pressure. Average systolic blood pressure was 103 versus 120 mm Hg in the remaining INTERSALT centers; diastolic blood pressure in these four population samples averaged 63 versus 74 mm Hg in the 48 other centers. There was little or no upward slope of blood pressure with age; hypertension was present in only 5% of the rural Kenyan sample and virtually absent in the other three centers. Also in marked contrast with the rest of the centers was level of daily salt intake, as estimated by 24-hour urinary sodium excretion. Median salt intake ranged from under 1 g to 3 g daily versus more than 9 g in the rest of INTERSALT populations. Average body weight was also low in these four centers, with no or low average alcohol intake, again unlike the other centers. The association within these four centers between the above variables and blood pressure was low, possibly reflecting their limited variability. While several other INTERSALT centers also had low average body weight or low prevalence of alcohol drinking, when this was accompanied by much higher salt intake (7-12 g salt or 120-210 mmol sodium daily), hypertension prevalence ranged from 8% to 19%. These findings confirm previous reports that in populations with a low salt intake, there is little or no hypertension or rise of blood pressure with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Cardiac status after four years in a trial on nutritional therapy for high blood pressure.

A randomized controlled trial demonstrated the ability of nutritional intervention in place of antihypertensive drugs to maintain blood pressure at normal levels for four years in 39% of less severely hypertensive patients whose blood pressure was previously well controlled by pharmacologic treatment. However, average blood pressures during the trial for patients in the intervention group were higher than those for a comparison group that continued to receive drug therapy throughout the study. Holter monitoring, echocardiography, roentgenography, and electrocardiography done at four years to determine whether blood pressure differences between groups were associated with differences in cardiac status did not indicate any differences in cardiac status favorable to one group compared with the other. Further investigation in larger samples is needed to assess any long-term differences in cardiac status based on such alternate therapies.

Adult↗
PubMed1989

The INTERSALT study: relations of body mass index to blood pressure. INTERSALT Co-operative Research Group.

In INTERSALT, the relationship between body mass index (kg/m2) and blood pressure was studied in 10,079 men and women aged 20-59, sampled from 52 centres around the world, based on a standardised protocol with central training of observers, a central laboratory and extensive quality control. Body mass index-blood pressure relationships were first studied in men and women within each centre, and results of these regression analyses were then pooled for all 52 centres. With adjustment for age, alcohol intake, smoking, and sodium and potassium excretion, body mass index was positively associated with systolic blood pressure among men in 51 of 52 centres and among women in 47, significantly so in 24 and 27, respectively. Body mass index was positively associated with diastolic blood pressure in 51 and 49 centres in men and women, respectively, significantly so in 33 and 31. When the within centre regression coefficients were pooled, the pooled coefficients were highly significant in all analyses (P less than 0.001), and were similar for those aged 20-39 and 40-59. Overall, a 10 kg difference in body weight was associated on average with a 3.0 mmHg difference in systolic and a 2.2 mmHg difference in diastolic pressure. In further analyses across centres, median body mass index was related significantly to median systolic blood pressure, median diastolic pressure and the prevalence of hypertension in both men and women. Body mass index was related to the slopes of systolic and diastolic blood pressure with age in women, but not in men. These INTERSALT findings confirm the importance of the association between body weight and blood pressure. Differences of 2-3 mmHg in systolic blood pressure on a population basis have been shown to be associated with differences in stroke mortality rates of 6-9 per cent and in coronary death rates of 4-6 per cent.

Adult↗
PubMed1988

Education, smoking and non-cardiovascular mortality: findings in three Chicago epidemiological studies.

The interrelationships among education, smoking, and non-cardiovascular (non-CVD) mortality were examined in middle-aged white males from the Chicago Peoples Gas Company Study (PG), the Chicago Western Electric Company Study (WE), and the Chicago Heart Association Detection Project in Industry (CHA). In each study, college graduates had the lowest prevalence of current smokers and the highest prevalence of former smokers. The associations between education and smoking were strongest in CHA, a study with baseline measurements 10-14 years after those of PG and WE and 3-8 years after the US Surgeon General's report on smoking and health in 1964. In PG and WE, the relative risks of non-CVD death for those who did not attend college compared to those who did were 1.50 and 1.38 (95% limits, 1.04 to 2.18 and 0.95 to 2.02). In CHA, the relative risk for those who did not graduate from college compared to those who did was 1.55 (1.17, 2.05). Differences in baseline cigarette smoking could account for only 23-29% of these increased risks. Because the associations between education and non-CVD mortality may have been confounded by changes in smoking status over the course of follow-up in these studies, non-CVD deaths were subdivided into those from causes related to smoking and causes not related to smoking. For smoking-related causes, the relative risk of death for those who did not attend/graduate from college was 1.95 (0.96, 3.95) in WE, 2.13 (1.18, 3.87) in PG, and 2.34 (1.47, 3.84) in CHA, while the relative risks for causes not related to smoking were 1.17, 1.12 and 1.16, respectively. These findings suggest that education is related inversely to non-CVD mortality primarily through smoking and smoking-related causes of death. With smoking becoming increasingly a habit of the less well-educated, these findings underscore the need for smoking prevention and cessation programmes targeted at the lower end of the socioeconomic scale.

Adult↗
PubMed1988

A comparison of the random-zero and standard mercury sphygmomanometers.

Both the standard mercury sphygmomanometer and the random-zero sphygmomanometer have been used in epidemiological studies and clinical trials. Problems arise in comparing studies since, in addition to other methodological differences, the readings obtained with the random-zero sphygmomanometer have been found to be lower than those obtained with the standard mercury sphygmomanometer. In the present study, blood pressures were measured in 66 subjects to examine the comparability of findings with the two instruments. Trained observers measured blood pressures simultaneously using a double-headed stethoscope and one cuff connected to the two sphygmomanometers. Use of instrument was randomly assigned for each blood pressure measurement; each observer was unaware of the other's blood pressure reading. Readings were lower with the random-zero sphygmomanometer; mean difference ranged from 2.5 to 3.3 mm Hg for systolic pressure and 1.9 to 2.7 mm Hg for diastolic pressure. Digit distributions recorded by the two observers for the standard mercury sphygmomanometer and the random-zero sphygmomanometer were not significantly different for either systolic or diastolic blood pressure. Intraindividual variation was greater with the random-zero sphygmomanometer than with the standard mercury sphygmomanometer. These data do not indicate that one instrument is clearly superior to the other, although in studies where the observer seeks to reduce the bias of multiple readings per person, the random-zero sphygmomanometer may be the more appropriate instrument. Critical to the use of either instrument are careful training, standardization, certification, and periodic recertification of observers.

Adult↗