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Biomedical subjects

B Burrows

Publications and source records attributed to B Burrows.

At least 55 records · Page 3Linked to original sources
PubMed1987

The course and prognosis of different forms of chronic airways obstruction in a sample from the general population.

We examined the course and prognosis in subjects selected from the general population who had chronic airflow obstruction at the time of their enrollment in a longitudinal epidemiologic study. Mortality and the rate of change in lung function were analyzed in relation to the initial clinical characteristics of the subjects. Twenty-seven subjects with symptoms and signs of asthma (Group I) had a higher survival rate and a much lower rate of decline in pulmonary function than the 45 subjects in Group III, whose clinical characteristics were more compatible with an emphysematous form of chronic obstructive pulmonary disease (COPD). The 10-year mortality among subjects in Group III (non-atopic smokers without a history of asthma) was close to 60 percent, whereas it was only 15 percent in Group I (atopic subjects or nonsmokers with known asthma). The mean overall rate of decline in forced expiratory volume in one second was 70 ml per year in Group III but less than 5 ml per year in Group I. Forty-five patients (Group II) who did not clearly fit into either Group I or III had intermediate values for survival and decline in pulmonary function. Previous data on mortality from COPD and the rate of progression of the condition, although compatible with our findings in patients who had an emphysematous form of disease, are not applicable to those with an asthmatic-bronchitic form. Better control of the progression of asthmatic bronchitis with therapy may explain its more favorable prognosis.

Asthma↗
PubMed1987

A longitudinal study of serum IgE in a community cohort: correlations with age, sex, smoking, and atopic status.

A number of factors, including age, sex, smoking habits, and atopic status have been reported in cross-sectional studies to influence levels of serum IgE. We have examined the effects of these variables on serum IgE in a community population cohort of 1109 subjects during a longitudinal study in which two serum samples were obtained 8 years apart from each subject. For the entire cohort, mean serum IgE level changed little during the follow-up period (28.9 versus 26.0 IU/ml). Most of the decreases were observed in children and young adults. Subjects more than the age of 35 years demonstrated no systematic change in serum IgE levels. By the end of follow-up (when there were few subjects still less than 16 years of age), significant relationships of IgE to age could no longer be demonstrated in nonatopic subjects. Also, in the nonatopic subjects of this cohort, there were no significant differences in IgE levels between the sexes. Among atopic subjects, there was a clear tendency for IgE to decrease with age, with atopic women more than 35 years of age demonstrating greater declines in IgE levels during follow-up than men of comparable age. The IgE levels in atopic male subjects were significantly higher than in atopic female subjects after the age of 35 years. Smoking was associated with an elevation in serum IgE. In this cohort, the smoking effect appeared to be limited to male subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Longitudinal changes in allergen skin test reactivity in a community population sample.

A cohort of 1333 subjects, aged 3 years and older, was followed for a mean of 8.1 years to assess changes in allergen skin test reactivity. The overall prevalence of reactivity to the five antigen mixtures was 39.1% during the initial survey and 50.7% after the follow-up period. The greatest increase in prevalence occurred among children and teenagers (22.2% and 19.5%) with only minimal increases after the age of 65 years (6.0%). No difference in prevalence between male and female subjects was apparent, either initially or at the end of the follow-up period. In-migration to the Tucson area was a major factor in determining changes in reaction prevalence. Among subjects more than 35 years of age, recent in-migrants accounted for most of the increased prevalence. Comparisons of atopy among consistent smoking groups confirmed the previous observation that smokers are less atopic than either nonsmokers or exsmokers, probably because of a self-selection process. In contrast, exsmokers were generally the most atopic, both initially and at the end of the longitudinal observation period. The high overall prevalence of allergen reactivity in this population is believed to be due in large measure to high year-round concentrations of multiple aeroallergens in the Tucson environment.

Adult↗
PubMed1987

Contrasting diet and body mass among users and nonusers of oral contraceptives and exogenous estrogens: the Lipid Research Clinics Program Prevalence Study.

Mean dietary constituent levels using the 24-hour recall method and body mass measures were examined among oral contraceptive and exogenous estrogen users and nonusers in the Lipid Research Clinics Program Prevalence Study. Among women aged 20-44 years, oral contraceptive users had a significantly lower mean Quetelet index of body mass and triceps skinfold thickness and a significantly higher total caloric intake. Among women aged 45-69 years, those taking exogenous estrogens had a significantly lower mean Quetelet index. No significant differences between hormone users and nonusers were seen for per cent of calories from fat (saturated or unsaturated), protein, carbohydrates, starch, sucrose, or alcohol. The higher total caloric intake in oral contraceptive users in contrast to nonusers and the lower body mass in both groups of gonadal hormone users may in part be indicative of other differences in life-style and behavior between the study groups. Further documentation of specific eating patterns, nutrient intake, and energy metabolism in women consuming gonadal hormones and in suitable control subjects seems to be indicated.

Adult↗
PubMed1987

Longitudinal study of pulmonary function development in childhood, adolescence, and early adulthood. Development of pulmonary function.

The growth of pulmonary function between 5.5 and 25 yr of age was determined using 1,511 observations over time on 353 subjects from a representative population sample of white non-Mexican-Americans in Tucson. There was an average of 8.8 yr of follow-up, with a maximum of 12. The method used was shown to be robust for span of follow-up from 3 to 12 yr (3 to 7 observations), and the results were verified by standard statistical methods. The standard error of the estimate decreased linearly with follow-up, indicating the need for longitudinal evaluation. Respiratory symptoms and diagnoses had the biggest negative impact on growth of lung function, using FVC, FEV1, Vmax50, and size-compensated flows (Vmax50/FVC). Smoking had the next biggest negative impact. Smoking cessation was shown to have a positive impact on growth of pulmonary function. Using a second linear model to adjust for individual variability and the random variability over surveys, individual growth showed similar trends. Further negative impacts were due to parental smoking, especially as it interacts with active smoking and respiratory disease. Flows at end of follow-up (Vmax50, Vmax50/FVC) were more sensitive than FEV1 to the effects of concurrent disease and smoking, and more persistent effects of these factors in early adulthood.

Adolescent↗
PubMed1987

The "horse-racing effect" and predicting decline in forced expiratory volume in one second from screening spirometry.

Longitudinal spirometric data on adults in a general population sample confirmed an overall relationship between rate of change in FEV1 (delta FEV1) and mean FEV1/Ht3. This relationship between FEV1 "slope" and "level" has been called a "horse-racing effect" and is the basis for the widely accepted concept that detecting a low FEV1 will predict a rapid decline in FEV1 and the development of clinically significant COPD. However, when both age and smoking habits were taken into account, the effect persisted only in male smokers. Even in them, it was dependent on the inclusion of part of the delta FEV1 in calculation of the mean FEV1 value. While neither a low initial FEV1/Ht3 nor percent predicted FEV1 significantly predicted a subsequent rapid fall in FEV1, presumably because of regression toward the mean, other initial spirometric variables proved better predictors, at least among male smokers. In them, a low FEV1/FVC ratio on entry was almost uniformly associated with a high rate of decline in FEV1. This was not seen in ex-smokers with similar initial spirometric findings. Also, delta FEV1 could not be predicted with any precision in women regardless of their smoking status. The findings strongly support the concept that detection of early airway disease by spirometric screening will identify those male smokers who are likely to develop clinically significant illness if they continue to smoke and that smoking cessation, even at this point, can markedly improve the prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Longitudinal changes in forced expiratory volume in one second in adults. Effects of smoking and smoking cessation.

Longitudinal changes in FEV1 (delta FEV1) in relationship to smoking habits were examined in 1,705 adults enrolled in a prospective study of a general population sample. In both men and women, there were excessive rates of decline in FEV1 in smokers, at least in those smoking more than 10 cigarettes per day. The excess decline of smokers was age dependent, particularly in men, with much of the excess loss of function occurring between 50 and 70 yr of age. Effects of smoking on delta FEV1, observed minus expected delta FEV1 and observed minus expected percent delta FEV1, were greater in men than in women even when controlled for current cigarette dose. Ex-smokers show delta FEV1 values similar to those of nonsmokers. In subjects younger than 35 yr of age, quitting smoking during follow-up was associated with an actual increase in FEV1. In men 50 to 70 yr of age, smoking cessation early in the study appeared to lead to a relatively prompt return to normal rates of functional decline. Thus, the findings suggest relatively prompt beneficial effect of smoking cessation even in late middle age.

Age Factors↗
PubMed1987

The single-breath carbon monoxide diffusing capacity. Reference equations derived from a healthy nonsmoking population and effects of hematocrit.

Measurements of the single-breath carbon monoxide diffusing capacity (DL) were obtained on a randomly selected sample representative of the white non-Mexican-American population of Tucson, Arizona. Methods of measurement followed the guidelines set forth in the ATS-sponsored Epidemiology Standardization Project. There were 228 healthy nonsmokers who had duplicate tests that met the criteria for being acceptable. On the basis of data from these subjects, reference equations were derived for DL, alveolar volume (VA), and DL/VA. The data demonstrate the effects of growth and development, height, and age on these variables. Because a significant proportion of women, but not of men, had low hematocrit values, an effect of hematocrit on DL and DL/VA could be demonstrated only in females in this population sample.

Adult↗
PubMed1986

Pneumococcus-specific immunoglobulin E in cigarette smokers.

A relationship between elevated serum immunoglobulin E levels and smoking has been demonstrated in epidemiological studies. Allergy skin test data suggest that the excess immunoglobulin E of smokers is not specific for aeroallergens. It is possible that the excess immunoglobulin E is specific for microorganisms that often infect the lower respiratory tract of smokers. To investigate this possibility we utilized a radioallergosorbent test assay for detecting serum immunoglobulin E specific for Streptococcus pneumoniae, an organism commonly isolated from the respiratory tract of smokers with chronic bronchitis. We assayed sera of thirty smokers and thirty nonsmokers for immunoglobulin E specific for Streptococcus pneumoniae. Individual sera were considered positive for pneumococcus-specific immunoglobulin E if the binding was at least twice the non-specific binding at the total immunoglobulin E concentration of the particular serum. Eleven of the thirty sera of smokers and two of the thirty nonsmokers were positive for pneumococcus-specific immunoglobulin E. By chi-square analysis of these data, the prevalence of pneumococcus-specific immunoglobulin E was significantly greater in the smoking group compared with the non-smoking group (P less than 0.02). These results suggest that the excess immunoglobulin E of smokers is, at least in part, specific for microorganisms that infect the airways.

Adult↗
PubMed1986

Longitudinal changes in forced expiratory volume in one second in adults. Methodologic considerations and findings in healthy nonsmokers.

Longitudinal changes in FEV1 (delta FEV1) have been examined in a sample of the general population of Tucson, Arizona. Adults with satisfactory spirometric tests in all 7 surveys performed over a period of 11 yr showed some between-survey differences in mean FEV1. Although small in absolute magnitude, such survey biases (which would be impossible to detect unless multiple spirometric tests were carried out on a relatively large group of subjects) could have a marked effect on calculated changes in FEV1 and may explain the widely divergent delta FEV1 values reported in the literature. After adjusting for survey biases, the relationships of delta FEV1 to age, sex, and body size were examined in "healthy" nonsmokers in the population who were followed for an average of 9.6 yr. The FEV1 showed an accelerating decline with age, and delta FEV1 was best explained by a model of proportional change in which it is a function of Age X Height3. Longitudinally determined delta FEV1 showed much less decline in function and a later apparent age of onset of decline than suggested by cross-sectional analyses. While small "learning effects" in longitudinal calculations cannot be excluded, most of the cross-sectional versus longitudinal differences are probably ascribable to past events that have adversely affected the FEV1 in older adults, thereby increasing cross-sectional age effects. Present findings also suggest that generally applicable "prediction equations" for delta FEV1 probably cannot be developed and that delta FEV1 values should only be compared between groups studied in an identical manner within a given study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Comparisons of asthma, emphysema, and chronic bronchitis diagnoses in a general population sample.

This report is an analysis of cases of obstructive lung disease diagnosed during the first 8 yr of a community study. Of 351 subjects who received a new diagnosis of asthma, emphysema, or chronic bronchitis from community physicians, 152 (44.5%) had a prior or concomitant diagnosis of another obstructive disease. Asthma developed most often in young subjects, emphysema in older subjects, and chronic bronchitis occurred in all age groups. Among older subjects, disease groups were surprisingly similar, with wheeze, dyspnea, and attacks of shortness of breath with wheeze all occurring frequently in diagnosed subjects, including those with emphysema. The majority of subjects who developed emphysema were males. In contrast, 72.8% of the asthma and chronic bronchitis subjects were females. These results suggest that physician bias may result in labeling male patients as emphysematous and female patients as asthmatic or bronchitic.

Adolescent↗
PubMed1986

Vectorcardiographic and blood pressure correlates of obstructive pulmonary diseases in a community population.

Vectorcardiography was performed on 2,449 subjects, aged six years and older, in the Tucson (Ariz) Epidemiological Study of Airway Obstructive Diseases (AOD), 95 percent of the white non-Mexican Americans in the stratified cluster population sample. The objectives were to confirm previous relationships and to determine if hypothesized changes in the vectorcardiogram (VCG) could predict AOD. Trained nurse technicians performed the VCGs, which were read and interpreted by a cardiologist. Vectorcardiographic results were broadly interpreted for abnormalities. Also, calculated vector means and angles were compared to standard questionnaire responses for medical history, to maximum expiratory flow-volume variables, and to values for blood pressure; these were all corrected for sex, age, height, weight, and the ponderal index. Values were expressed as percentages of predicted. Over 80 percent of the VCGs were found to be normal. Measured hypertrophy was related to disease; there were significantly more abnormalities in those with histories of heart disease, hypertension, arteriosclerosis, and AOD, when examined by types of ventricular hypertrophy and VCG-identified heart disease or hypertension; findings of AOD and heart disease were also correlated significantly. Of all the ventricular hypertrophy, right ventricular hypertrophy (RVH), type C, was confirmed to be the predominant type associated with decreased pulmonary function in all smoking groups. Systolic blood pressure was related to RVH, type A, and diastolic 4 and 5 blood pressure with RVH, types A and B. The vectors' magnitude and angles were related to abnormality of pulmonary function in those with and without heart disease and AOD.

Adolescent↗
PubMed1986

A prospective study of the natural history of asthma. Remission and relapse rates.

In this longitudinal study of a general population sample, remissions of asthma were common only during the second decade of life and were especially unusual in subjects ages 30 to 60 years on enrollment. Asthmatic subjects with severe symptoms, with reduced ventilatory function, or with a concomitant diagnosis of chronic bronchitis or emphysema on entry to the study were very unlikely to be in remission nine years later. Relapses of disease were common in subjects with a past history of asthma who were considered to be quiescent on enrollment to the study. Relapse rates tended to increase with age, at least up to the age of 70. Relapses were especially frequent among those "ex-asthmatics" who had persisting respiratory symptomatology on entry to the study.

Adolescent↗
PubMed1985

Methodological considerations of epidemiological diagnoses in respiratory diseases.

Since epidemiological research depends extensively on questionnaire responses, a comparison of such responses with a standardized medical evaluation was conducted. It was found that standardized questionnaires do well in comparison for certain kinds of information on chronic conditions. However, clinical evaluations will elicit more information, specifically of a milder nature. It was concluded that standardized epidemiological questionnaires are satisfactory for survey of chronic conditions.

Adolescent↗
PubMed1985

The epidemiology of asthma.

Significant strides have been made in recent years in the epidemiologic study of obstructive lung diseases including asthma. Community population samples are being evaluated prospectively and followed up longitudinally to document the appearance of morbidity and clinical diagnoses. Also, a variety of environmental, physiologic, and immunologic variables are being collected on a serial basis to correlate changes with the appearance (or disappearance) of recognizable disease. Unfortunately, until the semantics and diagnostic labeling of airway abnormalities becomes more precise, especially in the older population, the incidence and prevalence of disease will lack the precision it should have.

Adolescent↗