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M D Lebowitz

Publications and source records attributed to M D Lebowitz.

At least 55 records · Page 3Linked to original sources
PubMed1994

Physiologic measures: pulmonary function tests. Asthma outcome.

When the effectiveness of asthma interventions are evaluated in the research setting, the physiologic manifestation of asthma-variable airways obstruction-is always objectively measured by some of the following pulmonary function tests: (1) Baseline spirometry gives a highly accurate "snapshot" of asthma severity and the degree of airways obstruction. The FEV1, derived from spirometry, is the most reproducible pulmonary function parameter and is linearly related to the severity of airways obstruction. There are no contraindications for the test, spirometers are widely available at reasonable cost, and methods and result interpretation are comprehensively standardized. (2) The post-bronchodilator FEV1 measures the best lung function that can be achieved by bronchodilator therapy on the day of the visit and therefore is a more stable measure in asthmatics than comparing visit-to-visit baseline FEV1. Although a positive acute response to bronchodilator helps to confirm the diagnosis of asthma, the degree of bronchodilator reversibility from visit-to-visit (change in reversibility) is not a useful index of asthma outcome. (3) Airway responsiveness (bronchial challenge) measures the degree to which an individual withstands nonspecific stimuli that trigger asthmatic attacks. The methacholine challenge test is safe and requires less than an hour, but it requires more technical skill than baseline spirometry and is contraindicated in some situations. (4) Ambulatory monitoring, using peak flow meters or hand-held spirometers, provides multiple measurements of the degree of obstruction for days to weeks in the patient's natural setting. PEF meters are very inexpensive and almost all asthmatics can use them, but PEF results are less reliable than the FEV1. The often asymptomatic obstruction of an asthmatic has both short-term (within a day and day-to-day) and longer-term variations that are triggered by naturally occurring stimuli. These changes are measured by PEF lability but not by spirometry during clinic visits. (5) Other pulmonary function tests, such as absolute lung volumes and airways resistance, may provide confirmatory data, but the instruments are large, expensive, and technically demanding. The results of all the above pulmonary function tests are significantly correlated with each other and with symptom scores and medication use in large groups of patients with widely varying degrees of asthma severity. Since a "gold standard" with which to measure asthma severity does not currently exist, all of these tests contribute an additional amount of unique information when measuring asthma outcome in a clinical trial.

Adolescent↗
PubMed1994

Determinants of percent predicted FEV1 in current asthmatic subjects.

We analyzed the determinants of the percent predicted FEV1 of a large group of diagnosed asthmatic subjects in the Tucson Study of Airway Obstructive Diseases. The 261 subjects were 6 to 88 years old, and 150 (57.5 percent) were female. Although 29.1 percent of the subjects were current smokers and 24.1 percent were ex-smokers, we found that pack-years of smoking was not related to lung function. In addition, age of onset of disease, duration of asthma, eosinophil count, serum IgE level, and allergy skin test reactivity status did not influence the %FEV1. We did find that both severity of wheezing and age of the subject related significantly to %FEV1, and an interaction term of these two variables replaced wheeze and age in the multiple regression equation. Current physician-diagnosed chronic bronchitis and the reported severity of exertional dyspnea also related to %FEV1.

Adult↗
PubMed1993

Antecedent features of children in whom asthma develops during the second decade of life.

In this report we compare 36 subjects in whom asthma was first diagnosed between the ages of 10 and 20 with 297 control subjects. All subjects were studied at age 5 to 9. Among the subjects who acquired a new diagnosis of asthma (NDA), the diagnosis was usually preceded by lower respiratory tract symptoms (31 of the 36 subjects had respiratory symptoms or a diagnosis of rhinitis or chronic bronchitis before asthma developed). Among those tested, more of those with NDA had positive allergy skin test results (56.5%) before diagnosis than control subjects (29.6%; p < 0.05), and the subjects with NDA had higher levels of serum IgE than control subjects (mean log serum IgE = 2.27 in subjects with NDA, 1.76 in control subjects; p < 0.05). Pulmonary function tests revealed no significant differences in the groups before diagnosis. Using logistic regression, we determined that wheezing, cough, a diagnosis of chronic bronchitis, and a positive allergy skin test result were independent risk factors for asthma. When combinations of variables were used, subjects with wheezing and a positive allergy skin test result, cough and a positive test result, and also those with a prior diagnosis of chronic bronchitis alone were at highest risk of a subsequent diagnosis of asthma.

Adult↗
PubMed1993

Smoking cessation and changes in respiratory symptoms in two populations followed for 13 years.

To investigate the relationship between persistence and incidence rates of respiratory symptoms, and the cessation of cigarette smoking, the data from longitudinal studies conducted in Cracow, Poland and Tucson, USA were analysed jointly. Among 1722 subjects smoking at the beginning of the study, 468 had given up smoking at the 13-year follow-up. The persistence and incidence rates of chronic cough, chronic phlegm, wheeze and attacks of breathlessness were reduced by 50% in ex-smokers compared to the subjects continuing to smoke. The beneficial effects of smoking cessation were decreased in subjects smoking more cigarettes per day in the past and starting to smoke at a younger age. The symptoms were less likely if smoking ceased before the onset of any respiratory disease. These results were similar in the Cracow and Tucson populations, confirming the universal nature of the observations.

Adult↗
PubMed1993

Passive smoking and chronic respiratory disease symptoms in non-smoking adults.

A prospective study was conducted to investigate the possible effects of environmental tobacco smoke (ETS) on the development of definite symptoms of airway obstructive disease (AOD) in a non-smoking adult population. In all 3914 subjects completed a standardized respiratory symptoms questionnaire in 1977 and 1987 and a computerized algorithm was used to identify new cases of definite symptoms of AOD during the follow-up period. In multivariate logistic regression models which adjusted for age, gender, income, educational level, years smoked in the past, and concentrations of ambient air pollutants, ETS exposure during childhood only was associated with a relative risk (RR) of 1.09 (95% confidence interval [CI]: 0.69-1.79), during adulthood only with an RR of 1.28 (95% CI: 0.90-1.79), and during both childhood and adult life with an RR of 1.72 (95% CI: 1.31-2.23). Results were not significantly changed when only lifetime never-smokers were used in analyses, and no interaction between ETS exposure and concentrations of ambient air pollutants was observed.

Air Pollution↗
PubMed1993

An alternative method for comparing and describing methacholine response curves.

Tests of nonspecific airway hyperresponsiveness are frequently used in the study of asthma both in the clinical settings and in epidemiologic studies. However, standard methods for characterizing individual tests and comparing results between subgroups have not been established. The most frequently used method of characterizing response curves is to report the dose that results in a 20% fall in FEV1 from the initial or baseline FEV1 value (PD20FEV1). Other investigators have suggested using the response slopes. In this study we demonstrate an alternative method of analysis that uses all of each subject's response data, makes comparisons between subgroups, and can include explanatory covariables. This approach is demonstrated using methacholine challenge data obtained in New Zealand children at 9 and 11 yr of age. The results showed significant differences between the mean dose-response curves of wheezers and nonwheezers, that responsiveness increased with the frequency of reported wheeze, and that initial pulmonary function and serum IgE are significantly related to responsiveness. These factors were not always significant using more traditional methods of analysis, indicating an increased sensitivity with this method of analysis.

Adolescent↗
PubMed1993

Longitudinal methods for describing the relationship between pulmonary function, respiratory symptoms and smoking in elderly subjects: the Tucson Study.

In this study recently developed longitudinal techniques are used to examine the relationship between respiratory symptoms, smoking and pulmonary function measures in elderly subjects. The subjects were participants in the Tucson Epidemiological Study of Airways Obstructive Disease, aged > or = 55 yrs at the first survey 1972-1973, who had received pulmonary function testing and completed questionnaires in at least one of the six selected surveys. There were 633 males and 891 females, with up to 14 yrs follow-up included in the analysis. Based on their questionnaire responses, subjects were classified according to their respiratory symptoms and smoking habits at each survey. The pulmonary function testing included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and their ratio (FEV1/FVC). The pulmonary function data were analysed gender specific, with and without stratifying on vital status. The results indicate that respiratory symptoms are generally associated with lower levels of lung function, and that the impairment associated with chronic cough was observed predominantly in male subjects. The negative association of smoking was apparent in most measures, but was largest and most progressive in the FEV1/FVC ratios. Ex-smokers, in all cases, had better lung function values than current smokers, but their mean curves were always significantly below the values of nonsmokers.

Aged↗
PubMed1992

Effects of passive smoking on lung growth in children.

The objective of this study was to determine the effects of passive smoking on functional lung growth in children and adolescents. It was hypothesized that passive smoking might reduce lung function growth, especially in susceptible children. The assumption was that those most susceptible would be children who started with low lung function, as it had been shown that they had slower growth of lung function, and start to decline earlier. There were 138 non-Hispanic Caucasian children and adolescents, ages 5 through 15, who had at least three satisfactory longitudinal lung function tests over a 13 year period in the Tucson epidemiological study of airway obstructive diseases. Those who started in childhood with normal function did not show any effect of passive smoking, nor did females who started with low lung function. Males starting with low lung function whose parents smoked showed definite changes. Their forced expiratory volume in 1 second (FEV1) grew even more slowly between ages 13 through 16, related primarily to continuous parental smoking. They also had higher rates of decline for FEV1 to forced vital capacity (FVC) ratio and maximum flow at 50% vital capacity to FVC ratios than either the low function group without passive smoking or the normal function groups. This was independent of any symptoms or diagnoses present in this male low function group.

Adolescent↗
PubMed1992

The effects of airway hyperresponsiveness, wheezing, and atopy on longitudinal pulmonary function in children: a 6-year follow-up study.

We examined growth of spirometric lung function in 696 children of European ancestry who were followed from ages 9 to 15 years and stratified according to their degree of responsiveness to methacholine inhalation challenge, atopic status, and respiratory symptoms. Subjects were participants in the longitudinal Multidisciplinary Health and Development Study in Dunedin, New Zealand. Forced expired volume in 1 second (FEV1), and vital capacity (VC) were measured at 9, 11, 13, and 15 years of age, concurrently with assessment of airway responsiveness determined by the concentration of methacholine causing a 20% fall in FEV1 (PC20 FEV1). Atopic status was assessed at age 13 by skin-prick testing to 11 allergens. In children demonstrating airway hyperresponsiveness, FEV1 increased with age at a slower rate, and the FEV1/VC ratio had a faster rate of decline through childhood, compared to non-responsive children. Subjects with positive skin tests to house dust mite and cat dander also had lower mean FEV1/VC ratios than the control group. Any reported wheezing was associated with slower growth of FEV1 and VC in males. We conclude that in New Zealand children with airway responsiveness and/or atopy to house dust mite or cat growth of spirometric lung function is impaired.

Adolescent↗
PubMed1992

Longitudinal effects of passive smoking on pulmonary function in New Zealand children.

In this study we examined the longitudinal effects of smoke exposure on lung function in a cohort of New Zealand children observed from 9 to 15 yr of age. Possible exposures included in utero exposure from mothers smoking during pregnancy, passive smoke from parents, and active smoking by the children. Lung function measures of forced expiratory volume in one second (FEV1) and vital capacity (VC) were measured biennially and ratios (FEV1/VC) were computed. The data were analyzed using longitudinal methodology, and all subjects with at least one pulmonary function test and responses to the questions concerning smoke exposures were included (n = 634). Subjects reporting wheeze or asthma were examined as a separate subgroup. In the whole cohort, no significant detrimental effects were detected for absolute FEV1 or VC in either sex, related to active or passive smoke exposures. Parental smoking was, however, associated with persistent but mild and nonprogressive impairment of the FEV1/VC ratio in males, an effect that was present at the time lung function measurements were first made. This effect was not seen in females. In children with reported wheeze or asthma, parental smoking had progressive, more serious, and clinically significant effects on the FEV1/VC ratio among adolescents of both sexes, causing a mean reduction in FEV1/VC ratios by age 15 of 3.9% in males and 2.3% in females, in contrast to the observed increase in FEV1/VC ratios with age seen in nonexposed wheezing children. We conclude that passive smoking is a major contributing factor to the development and persistence of airflow limitation in wheezing children.

Adolescent↗
PubMed1992

Risk factors associated with complaints of insomnia in a general adult population. Influence of previous complaints of insomnia.

BACKGROUND: Insomnia is a common complaint both in the general population and also in physician's offices. However, risk factors for the development of insomnia complaints have not been completely identified. METHODS: To identify population characteristics associated with increased prevalence of insomnia complaints, we surveyed a large general adult population in 1984 through 1985. We evaluated the relationship among current complaints of initiating and maintaining sleep and obesity, snoring, concomitant health problems, socioeconomic status, and documented complaints of difficulty with insomnia 10 to 12 years previously. RESULTS: The strongest risk factor for complaints of initiating and maintaining sleep was previous complaints of insomnia (odds ratio, 3.5). In addition, female gender (odds ratio, 1.5), advancing age (odds ratio, 1.3), snoring (odds ratio, 1.3), and multiple types of concomitant health problems (odds ratios, 1.1 to 1.7) were all risk factors associated with an increased rate of complaints of initiating and maintaining sleep. CONCLUSION: Complaints of insomnia tend to be a persistent or recurrent problem over long periods of time. Female gender, advancing age, and concomitant health problems also are important risk factors.

Adult↗
PubMed1992

Continuous longitudinal regression equations for pulmonary function measures.

The data from a longitudinal population study in Tucson, Arizona, were used to describe the development and decline of maximal expiratory flow-volume (MEFV) measures with age. On the basis of their answers to self-administered questionnaires, in 9 of the first 10 surveys (1972-1988) and having performed at least one MEFV test, 930 nonsmoking healthy subjects were selected, providing 3,848 individual observations. The data were analysed using statistical methods that yield continuous piecewise linear regression equations and allow subjects to have repeated measures which are unequally spaced and at different times for different subjects. In addition, the age intervals for the piecewise linear line segments are estimated for each of the MEFV indices, as part of the modelling procedure. The resulting predicted values are compared between sexes and to previously published cross-sectional results from the same population. All MEFV measures in healthy subjects have an early increase in the rate of development corresponding to the onset of the adolescent growth spurt. This rapid growth period is followed by a plateau phase which lasts around 10 yrs for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in males, in which growth continues, but at a much lower rate. The plateau phase, is followed by a constant rate of decline which lasts throughout adulthood. In contrast, flow measures did not have a detectable plateau period, but did have points of increased rates of decline much later in life.

Adult↗
PubMed1992

Changes in chronic respiratory symptoms in two populations of adults studied longitudinally over 13 years.

Data from two longitudinal studies conducted in Cracow, Poland, and Tucson, Arizona, USA, were used to evaluate the differences in period prevalence, incidence and remission rates of respiratory symptoms between two populations, as well as to assess the between-cities similarities in the relationships of the symptoms to age and smoking habit. The analysis was based on data from 3,082 adult Cracow residents, interviewed twice 13 yrs apart, and from 1,452 Tucson adults, with mean period between initial and final survey of 12.2 yrs. Log-linear models were used to consider possible interactions of the symptoms, age, smoking, gender and city. The relationship of the symptoms to smoking was similar in both cities, after adjustment for age and gender, with at least doubled incidence rates of most symptoms in continuous smokers compared to lifetime nonsmokers. The between-population differences in the symptoms were related to age, indicating onset of bronchitic symptoms occurring earlier in life in Cracow, and of asthmatic symptoms in Tucson. These differences were due to factors other than tobacco smoking e.g. various types of ambient air pollution.

Adult↗
PubMed1991

Risk factors for respiratory syncytial virus-associated lower respiratory illnesses in the first year of life.

The relation of breast feeding and other factors to the incidence of respiratory syncytial virus-associated lower respiratory tract illness (RSV-LRI) in the first year of life is examined. The study population is 1,179 healthy infants enrolled at birth between May 1980 and January 1984 into the Tucson Children's Respiratory Study, Tucson, Arizona. Each subject's data were assessed at each month of age during the first year of life, during those months when respiratory syncytial virus was isolated. A number of significant relations were observed, particularly between 1 and 3 months of age. At this age, the risk of having a RSV-LRI increased in association with less than 1-month or no breast feeding, with being male, and with increasing numbers of others sharing the child's bedroom. In multivariate analysis, only sex and the number of others sharing the room remained as significant direct effects. However, a significant interaction demonstrated that breast feeding has a protective role in relation to RSV-LRIs for those infants of mothers with a lower education level. The risk of having a RSV-LRI increases with combinations of risk factors. Being in day care was a significant risk factor in the 7- to 9-month age range. The RSV-LRI rate also varies by birth month. A separate case-control study assessed relations of RSV-LRIs with cord serum RSV antibody. Those with lower cord serum RSV antibody, who also have minimal breast feeding, were found to be especially at risk for RSV-LRIs in the first 5 months of life.

Antibodies, Viral↗
PubMed1991

Death certificate reporting of confirmed airways obstructive disease.

Death certificate reporting of chronic airways disease was examined during 13 years of follow-up in the Tucson Epidemiologic Study of Airways Obstructive Disease. The Tucson study population is a geographically clustered stratified random sample of white, non-Mexican-American households in Tucson, Arizona. The initial survey was performed in 1972-1973. Using clinical and physiologic criteria from nine surveys to define airways obstructive disease in the population, the authors compared death certificate reporting with these criteria as the underlying cause and as reported anywhere on the death certificate. Reporting was related to the degree of antemortem airways obstruction. Sex differences in reporting were also noted. Females showed greater rates of reporting at low levels of impairment while males showed greater reporting at high levels of impairment. When airways obstructive disease was not the underlying cause of death, the type of underlying cause was found to affect reporting of airways obstructive disease on the death certificate.

Adult↗
PubMed1991

Methodology for generating continuous prediction equations for pulmonary function measures.

A mathematical procedure is described for fitting piecewise linear equations constrained to join at estimable multiple junctions or breakpoints. The model parameters, a combination of both linear and nonlinear, are estimated using a "Separable Least Squares" algorithm. In this algorithm the linear parameters, estimated using the General Linear Model, are nested within the iterations of a nonlinear optimization routine. This formulation allows additional covariates to be included in the model and can be easily expanded to include any number of line segments, both linear and nonlinear. The procedure is demonstrated by estimating continuous lung function reference equations for healthy normal subjects. Comparison of these reference equations with previously published equations derived for the same subjects, illustrates the advantages of having continuous equations throughout the age range of the data.

Adolescent↗