The epidemiology of emphysema.
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Biomedical subjects
Publications and source records attributed to B Burrows.
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In this study of a general population sample in Tucson, Ariz., smokers showed higher levels of serum IgE despite having a lower rate of allergy skin-test reactivity to common aeroallergens than nonsmokers. The prevalence of rhinitis was closely related to the level of serum IgE in atopic subjects regardless of smoking habits. In nonatopic smokers, elevated IgE levels were not associated with high rhinitis rates. However, high IgE levels in nonatopic smokers were related to increased rates of diagnosed asthma, wheeze, and chronic cough and/or sputum (C/S). These relationships were especially striking in subjects over the age of 54. In older nonatopic smokers, reported prevalences of "chronic bronchitis" and of functional impairment also increased in relation to the level of serum IgE. Reduced ventilatory function showed this relationship to IgE only when accompanied by C/S. It is suggested that the excess IgE related to smoking is qualitatively different than that found in subjects reacting to aeroallergens, is not important in the pathogenesis of upper respiratory tract disease, but may play a role in the development of some lower respiratory tract disorders.
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To examine criteria to assess significant changes of measurements derived from the forced expiratory vital capacity (FVC), and to examine changes in the peak expiratory flow (PEF) maneuvers, ten subjects were tested on approximately 30 occasions. Since mini Wright peak flow meters are increasingly used for clinical and research purposes, peak flow intraindividual variability and relations to FVC peak flow were examined, each set of tests consisting of five FVC maneuvers and one peak flow. Measurements on a pneumotachograph included FVC, (FEV1), maximum mid-expiratory flow (MMF or FEF25-75%), and instantaneous maximum expiratory flow after 50 and 75 percent expiration of the FVC. PEF measurements were derived using the mini Wright peak flow meter and the pneumotachograph. The coefficients of variation for the FVC measurements were greatest for maximum expiratory flow measurements and least for the FVC and FEV1. Maximum values from each set of tests reduced the variability. From these values, criteria and estimates were derived to evaluate significant intraindividual change. The PEF measurements were evaluated also to determine intraindividual changes. The coefficients of variation were only 2 percent to 14 percent. The peak flows obtained were shown to correlate well with the PVC peak flow.
The distribution of total serum IgE determined by the paper radioimmunosorbent test (PRIST) is examined in a large random stratified community population. Prior to logarithmic conversion the distribution of this immunoglobulin is not normal, with almost 40% of values below 20 IU/ml. A normal distribution occurs following such conversion, with a geometric mean value of 32.1 IU/ml. Both age and sex, in addition to atopic status, relate to IgE level. In both sexes highest levels occur among 6- to 14-year-olds, and males have higher levels than females at any given age. Women over age 75 yr have the lowest levels (geometric mean 9.2 IU/ml). Subjects with positive skin test results have several times the concentration of IgE as their nonatopic counterparts.
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Data from adults enrolled in a general population study in Tucson, Arizona, indicated that smokers have higher serum IgE concentrations than nonsmokers, despite a lower rate of allergy skin test reactivity, at least after 35 yr of age. After 15 yr of age there was a significant decline in serum IgE with age in both allergy skin test positive and skin test negative nonsmokers but no significant age decline was noted in similar groups of smokers. Ex-smokers showed a decline in serum IgE concentrations since quitting cigarettes. Also, the marked increase in geometric mean IgE that was seen in nonsmokers during the spring was not observed in smokers. The data suggested that smoking leads, directly or indirectly, to an increase in serum IgE and that this excess IgE may be qualitatively different from that seen in nonsmokers. Possible mechanisms for the effect are discussed. The observations raised the possibility that some of the adverse health effects of smoking might be immunologically mediated.
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Lung cancer was found in 20 (9.8%) of 205 patients with cryptogenic fibrosing alveolitis (CFA) or 12.9% of the 155 patients in this series followed to death. An excess relative risk of lung cancer of 14.1 was found in patients with CFA compared to the general population of comparable age and sex, allowing for the lengths of follow-up of the CFA patients. The relative risk for male smokers was (observed/expected) 15+1.06 = 14.2, and for female smokers (O/E) 2/0.3 = 6.7. Only one male and one female non-smoker had lung cancer. These data suggest that there is an excess risk of lung cancer not wholly accounted for by age, sex, or smoking habit. The distribution of histological types was not obviously different from that found in lung cancer without pulmonary fibrosis. Large opacities suggestive of lung cancer were present at the time of first hospital attendance for symptoms relating to CFA in four of the 20 patients. Finger clubbing was present in 19 (95%) compared with 116/185 (63%) of those so far not developing cancer. There were no other clinical differences at presentation. In particular, cancer was not found especially in those with longer survival from the onset of symptoms of CFA or with a greater initial radiographic change.
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We have examined the prevalence of incidence of asthma and other wheezing syndromes in subjects in a longitudinal epidemiologic study. The point prevalence of asthma was 6.6%, with the highest rates occurring in children. Rates were also relatively high in older subjects, in most of whom "chronic bronchitis and/or emphysema" had been concomitantly diagnosed. Other wheezing was very common in this population sample; in most age groups, the point prevalence rates of some form of wheezing exceeded 30%. New asthma developed in 1.4% of the subjects who were followed over a period of approximately 4 yr. New attacks of shortness of breath with wheeze occurred in 10.3% of the subjects at risk over the same time period. The incidence of asthma was greatest in young children, was least in late adolescence, and increased again in early adult life. The incidence was 1.5 times greater in young boys than in young girls but was much greater in women older than 40 yr of age, perhaps reflecting the diagnostic biases of physicians. In subjects younger than 40 yr of age, onset of the disease was strongly associated with previously demonstrated allergy skin test reactivity. New disease in this age group occurred de novo, primarily within the first few years of life or during early adult life. Subjects in whom asthma developed after 40 yr of age usually had prior symptoms of chronic bronchial irritation and often had obvious spirometric abnormalities. The disease in these subjects was not associated with positive allergy skin test reactions. Because in these older subjects it does not appear possible to clearly distinguish "asthma" from "chronic bronchitis," the label "asthmatic bronchitis" appears to be a reasonable descriptive term for this syndrome.
The percentage of eosinophils (%EOS), determined from a differential blood smear, was measured in 2,311 subjects enrolled in a general population study in Tucson, Arizona. A subgroup of 290 subjects was tested in more detail during a later evaluation in which absolute eosinophil counts, leukocyte counts, and nasal smears for eosinophils were obtained. In men, but not in women, there was a significant tendency for the %EOS to decrease with age. The highest %EOS was noted during the months of February through May, the time when most plants in this region are in bloom. Blood eosinophils were significantly related to allergy skin test reactivity, circulating IgE concentrations, several respiratory symptoms and disease diagnoses, as well as to reduced ventilatory function. Among subjects younger than 55 yr of age, however, ventilatory function was significantly low, and symptom rates increased only when there was allergy skin test reactivity in addition to eosinophilia. Neither allergy skin test reactivity nor eosinophilia alone was related to ventilatory function in this age group. Among older subjects, blood eosinophilia was associated with definite impairment of ventilatory function, regardless of skin test reactivity and independent of smoking habits. The presence of eosinophilia identified a predominantly female group of elderly nonsmokers with markedly impaired ventilatory function. These subjects appeared to fall into the clinical category of "asthmatic bronchitis".
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The relative usefulness of various initial findings in predicting survival is reported for 200 patients with chronic obstructive pulmonary disease who have been followed for approximately 15 years. After 5 years of follow-up, subjects 62 or more years of age showed a poorer survival rate than younger subjects. After controlling for age, the per cent predicted forced expiratory volume in 1 sec after administration of bronchodilator was the best indicator of prognosis. In subjects less than 65 years of age, the presence or absence of cor pulmonale further improved the prediction of subsequent mortality. Regardless of initial findings, however, there was wide individual variability in prognosis, and factors relating to this variability remain obscure. No difference in survival rate was noted between the 178 male patients who were enrolled in Chicago 15 years ago and the 100 similarly impaired men enrolled in Tucson approximately 7 years ago.
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The response of forced expiratory flow to inhalation of isoproterenol was evaluated in a general population sample of 1,063 subjects. Percentage changes in the forced expiratory volume in 1 sec and in the maximal flow measured at 50 percent of the initial expired forced vital capacity appeared to be the best indicators of responsiveness to bronchodilator. Subjects with a history of asthma more often showed responsiveness than did the remainder of the population, even when their initial function was within normal limits. Over-all, a high proportion of subjects with abnormalities in baseline forced expiratory volume in 1 sec or maximal flow after exhalation of 50 per cent of the forced vital capacity showed sufficient improvement after bronchodilator to cause their values after isoproterenol to fall within the normal range. The data suggest that responsiveness to bronchodilator aerosol may be a useful guide to the presence of bronchial reactivity in epidemiologic studies of obstructive airway diseases.