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Biomedical subjects

B Burrows

Publications and source records attributed to B Burrows.

At least 37 records · Page 2Linked to original sources
PubMed1989

Association of asthma with serum IgE levels and skin-test reactivity to allergens.

We investigated the association of self-reported asthma or allergic rhinitis with serum IgE levels and skin-test reactivity to allergens in 2657 subjects in a general-population study. Regardless of the subjects' status with respect to atopy or their age group, the prevalence of asthma was closely related to the serum IgE level standardized for age and sex (P less than 0.0001), and no asthma was present in the 177 subjects with the lowest IgE levels for their age and sex (greater than 1.46 SD below the mean). The log odds ratio increased linearly with the serum IgE level after we controlled for possible confounders and the degree of reactivity to skin tests. In contrast, allergic rhinitis appeared to be associated primarily with skin-test reactions to common aeroallergens, independently of the serum IgE level. We conclude that asthma is almost always associated with some type of IgE-related reaction and therefore has an allergic basis, although not all the allergic stimuli that cause asthma appear to have been included in the battery of common aeroallergens we used to assess atopic status. These findings challenge the concept that there are basic differences between so-called allergic ("extrinsic") and nonallergic ("intrinsic") forms of asthma.

Adolescent↗
PubMed1989

The effects of cigarette smoking and smoking cessation on the carbon monoxide diffusing capacity of the lung in asymptomatic subjects.

The single-breath carbon monoxide diffusing capacity (DL) was measured together with standard spirometry as part of a survey of a randomly selected community population sample. Based on answers to a self-administered questionnaire, subjects free of respiratory symptoms or disease were identified. Data from subjects who had never regularly smoked cigarettes had been used to derive reference equations for the test variables, and data from the remaining subjects who had smoked were examined to determine the effect of smoking and smoking cessation on the DL. From this cross-sectional analysis, it is apparent that cigarette smoking is associated with a decrease in DL that occurs very soon after beginning the cigarette habit. There is an irreversible decrease in DL with cumulative cigarette consumption, but also a reversible phenomenon that leads to rapid improvement in DL on smoking cessation.

Adolescent↗
PubMed1989

The course and prognosis of different types of chronic airflow limitation in a general population sample from Arizona: comparison with the Chicago "COPD" series.

Recently reported data from a general population study in Tucson, Arizona have shown that subjects who have an "asthmatic bronchitic" type of chronic airways obstruction have a much more benign course than equally impaired subjects who have the typical smoking-induced, and presumably emphysematous, form of disease. These data are reviewed briefly. Findings in these subjects are then compared with those in "COPD" patients enrolled in an "emphysema clinic" in Chicago many years ago; patients with asthmatic features had been systematically excluded from the Chicago series. The rate of decline in FEV1 and mortality of Arizona subjects considered to have "typical COPD" were remarkably similar to those in the Chicago series after accounting for age and initial FEV1, but Arizona subjects with features suggesting "chronic asthmatic bronchitis" had a much more favorable prognosis than either of the "COPD" groups. These different forms of chronic airways obstruction should be distinguished in clinical or epidemiologic studies of airways obstructive disorders.

Adult↗
PubMed1989

A mathematical procedure for estimating the spatial relationships between lung function, somatic growth, and maturation.

A mathematical procedure is described for examining growth velocity rates of lung function (FEV1) in relationship to somatic growth and maturation. This procedure uses a polynomial smoothing spline model to yield a fitted curve through the data and to estimate the process first derivatives (i.e. growth velocity curves). We demonstrate this technique using data from children and adolescents enrolled in the Tucson Epidemiological Study of Airway Obstructive Diseases. The study group consisted of 772 healthy normal subjects, aged 3 to 25 y. The results for the normal subjects (male and female) indicate that the growth velocity peak (GVP) of somatic growth leads the GVP of functional growth (FEV1) by approximately 7 and 11 mo for females and male subjects, respectively, and that the GVP of maturation lags behind that of functional growth (FEV1) by approximately 1 y (male and female subjects). In addition, the normal subjects' growth velocity curves for FVC and FEV1/FVC were examined. The FEV1/FVC ratio was consistently high, and its growth velocity was not significantly different than 0 over the age range studied. This suggests that in normal children, the GVP seen in FEV1 is primarily due to a GVP in vital capacity or lung vol, rather than to a direct effect on expiratory flow rates alone. From this study we concluded that the polynomial smoothing spline procedure can adequately model the inherently noisy pulmonary function data and additionally yield an accurate estimate of the process first derivative.

Adolescent↗
PubMed1989

Decline of height with age in adults in a general population sample: estimating maximum height and distinguishing birth cohort effects from actual loss of stature with aging.

The decline in stature with age among adults is well documented. Although part of this represents a birth cohort effect, actual height declines among older individuals are known to contribute to the effect. In this study we used longitudinal changes in the heights of adults in a general population sample to determine the rate of decline in height over time in individuals of different ages. This allowed an estimation of the age at which decline in height begins, a value close to age 40 in both sexes. It also allowed derivation of equations from which the maximum height of subjects can be estimated on the basis of their sex, current height, and age. These equations should prove useful when examining the effect of aging per se on physiological measurements that are height dependent. The data also allow one to compare the magnitude of the effect of year of birth with that of the actual decline in height seen among the elderly. We estimate that approximately 60% of the smaller stature of older male subjects and 45% of the smaller stature of older female subjects is a birth cohort effect deriving from the secular trend toward greater stature; the remainder is a result of an actual decrement in height after the age of 40.

Adult↗
PubMed1988

A reexamination of risk factors for ventilatory impairment.

Previous cross-sectional analyses of data from the Tucson Epidemiological Study of Airways Obstructive Diseases have shown significant relationships of ventilatory impairment to a variety of risk factors, including smoking, chronic productive cough, a history of childhood respiratory illnesses, atopy, blood eosinophilia, and serum immunoglobulin E (IgE). In the present report, we reexamine these relationships in subjects 40 to 74 yr of age to determine the effect of excluding known asthmatics who, as a group, have markedly impaired lung function. After exclusion of asthmatics, atopy, eosinophilia, and IgE no longer appear to be significant risk factors for ventilatory impairment, and nonasthmatic nonsmokers show almost no remaining ventilatory impairment. In current smokers, quantitative relationships of FEV1 to pack-years of cigarette consumption and to chronic productive cough are changed little by excluding asthmatics. In nonasthmatic ex-smokers, however, age at quitting smoking adds significantly to prediction of FEV1 after accounting for pack-years. Young ex-smokers closely resemble nonsmokers, but they become increasingly similar to current smokers as their age at quitting increases. A history of respiratory trouble before 16 yr of age continues to appear to increase susceptibility to smoking effects, even after exclusion of asthmatics. But, as in previous studies, the possible bias of preferential recall of childhood illnesses by impaired subjects limits interpretations of this observation. On the other hand, present findings suggest that such factors as atopy, eosinophilia, and elevated serum IgE may well be risk factors for persistent asthma, but they have no relationship to nonasthmatic forms of chronic obstructive pulmonary disease (COPD).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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↗