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Biomedical subjects

W O Spitzer

Publications and source records attributed to W O Spitzer.

At least 55 records · Page 3Linked to original sources
PubMed1993

Is the association between inhaled beta-agonist use and life-threatening asthma because of confounding by severity?

We have previously reported an increasing dose-response relationship between the regular use of beta-agonist inhalers and the risk of asthma death and near death among a cohort of 12,301 subjects who had been dispensed 10 or more prescriptions of asthma drugs from January 1980 to April 1987. That analysis was based solely on information obtained from linkable computerized data bases. Such an association might be explained in part by the tendency of patients with more severe asthma, that is, those at greatest risk for an adverse outcome, to use more beta-agonist medication. To further examine this potential confounding by severity, we gathered clinical information independently from the field on the 129 case patients and their 655 control patients from the matched case-control analysis of 12,301 subjects. In 68% of the control patients with a life-threatening episode and 75% of the matched control subjects, we obtained a valid questionnaire from at least one physician who had seen the patient during the previous 2 yr. Acceptable information on hospitalizations because of asthma was obtained in 87% of those hospitalized. Clinical features associated with an increased risk of fatal and near-fatal asthma were: a history of loss of consciousness or seizures during a previous asthma attack (odds ratio, 10.2; 95% CI, 3.9 to 26.7), a history of attacks of asthma precipitated by eating certain foods (odds ratio, 5.1; 95% CI, 2.4 to 11.1), a clinical score designed to reflect the severity of prior attacks of asthma leading to hospitalization, and prior respiratory acidosis among those in whom a blood gas determination was recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1992

Effect of negative pressure ventilation in severe chronic obstructive pulmonary disease.

The hypothesis that patients with chronic obstructive pulmonary disease (COPD) have chronic inspiratory muscle fatigue was tested in an effectiveness trial in which negative pressure ventilation (NPV) was used to produce inspiratory muscle rest. In a double-blind study 184 patients with severe COPD were randomly allocated active or sham NPV treatment for a 12-week period of home use. The distance walked in a 6 min walk test was the primary outcome variable. Secondary outcome measures were cycle exercise endurance time, severity of dyspnoea, quality of life, arterial blood gas tensions, and respiratory muscle strength. The percentage reduction in amplitude of the diaphragmatic electromyographic signal multiplied by hours of NPV was used to reflect the dose of NPV so we could examine dose-response relations. Analysis was based on intention to treat. We found no evidence of a clinically or statistically significant difference in any outcome measure between active and sham groups. No dose-response relation was observed. Moreover, the intervention was poorly accepted despite substantial clinical support. We conclude that NPV as used in this study is difficult to apply and ineffective when used with the aim of resting the respiratory muscles in patients with stable COPD.

Aged↗
PubMed1992

The use of beta-agonists and the risk of death and near death from asthma.

BACKGROUND: Morbidity and mortality from asthma appear to be increasing, and it has been suggested that medications used to treat asthma are contributing to this trend. We investigated a possible association between death or near death from asthma and the regular use of beta 2-agonist bronchodilators. METHODS: Using linked health insurance data bases from Saskatchewan, Canada, we conducted a matched case-control study of subjects drawn from a cohort of 12,301 patients for whom asthma medications had been prescribed between 1978 and 1987. We matched 129 case patients who had fatal or near-fatal asthma with 655 controls (who had received medications for asthma but had not had fatal or near-fatal events) with respect to region of residence, age, receipt of social assistance, and previous hospitalization for asthma. RESULTS: The use of beta-agonists administered by a metered-dose inhaler was associated with an increased risk of death from asthma (odds ratio, 2.6 per canister per month; 95 percent confidence interval, 1.7 to 3.9) and of death or near death from asthma, considered together (odds ratio, 1.9; 95 percent confidence interval, 1.6 to 2.4). For death from asthma, use of the beta-agonist fenoterol was associated with an odds ratio of 5.4 per canister, as compared with 2.4 for the beta-agonist albuterol. On a microgram-equivalent basis, the odds ratio for this outcome with fenoterol was 2.3, as compared with 2.4 with albuterol. CONCLUSIONS: An increased risk of death or near death from asthma was associated with the regular use of inhaled beta 2-agonist bronchodilators, especially fenoterol. Regardless of whether beta-agonists are directly responsible for these adverse effects or are simply a marker for more severe asthma, heavy use of these agents should alert clinicians that it is necessary to reevaluate the patient's condition.

Administration, Inhalation↗
PubMed1992

Acute low back pain and economics of therapy: the iterative loop approach.

We use the measurement iterative loop as a conceptual framework to examine the economics of common therapies for acute non-specific low back pain. The measurement iterative loop systematically assesses the interlocking facets of an illness from the community health perspective, including quantifying burden of illness, etiology, assessment of therapeutic effectiveness, and economic evaluation of therapies. The iterative loop reveals that: (1) burden of illness, although known to be substantial, is so far inaccurately measured, (2) little is known about such factors as provider and patient compliance; and (3) the economics of therapy can guide us in this time of clinical uncertainty when no therapy appears clearly superior. For therapies with at least some support from randomized controlled trials, bedrest appears to be economically superior. Besides burden of illness, compliance, and current therapies, future research should address such "therapeutic" options as early return to work and patient self-management.

Acute Disease↗
PubMed1991

A randomized clinical trial of negative pressure ventilation in severe chronic obstructive pulmonary disease: design and methods.

This report documents the design and methods of a randomized clinical trial designed to test the effectiveness of home negative pressure ventilation in patients with severe chronic obstructive pulmonary disease. Active negative pressure ventilation was compared with a sham version of the treatment after a pre-trial assessment had indicated the feasibility of the latter. Over 1200 patients in the metropolitan Montreal area were screened. Of these, 348 patients were recruited to enter a 4-week stabilization period, and 184 were subsequently randomized to receive either active or sham negative pressure ventilation. A 5-day in-hospital period was used to train patients in ventilator use and obtain baseline measures of exercise capacity, lung function, respiratory symptoms, and quality of life. Home ventilation treatment took place during a following 12-week period. Respirator use was recorded both from patient logs and from concealed meters installed in the units. Patients received four home visits by physiotherapists during the 12-week period and returned for follow-up to the hospital 4 and 12 weeks post-discharge for reassessment.

Aged↗
PubMed1990

The use of biomarkers in the prediction of survival in patients with pulmonary carcinoma.

Data on ten variables and 16 biomarkers were obtained on 119 patients with newly diagnosed pulmonary cancer. The prognostic value of 16 biomarkers (alpha-1-antitrypsin [AAT], adrenocorticotropic hormone [ACTH], alpha-fetoprotein [AFP], carcinoembryonic antigen [CEA], human chorionic gonadotropin [HCG], immune complexes, immunoglobulins, N-terminal peptide of proopiomelanocortin [NTERM], and tumor-associated antibody [TAA]) was tested by adding these to the model of age, gender, stage, morphology, Feinstein's classification of symptoms, Karnofsky scale, leukocyte count, recent weight loss, and liver enzymes. Using Cox's regression method and a forward stepwise procedure, seven biomarkers (ACTH, AAT, AFP, calcitonin, HCG, TAA, and prolactin) entered the model. Elevated levels of cortisol and TAA were associated with longer survival. The selection of biomarkers by stepwise regression needs to be interpreted with caution, especially since the Z scores were found to be dependent on the particular variables included in the model. Furthermore, when dichotomized on maximum of the normal laboratory values, HCG and AFP were infrequently (2%) elevated. The lack of correlation among the biomarkers supports the hypothesis of random derepression of the genome of cancer cells. Further studies in improved modeling and the formulation of a biomarker index could enhance our understanding of the biology of cancer.

Adenocarcinoma↗
PubMed1990

Links between passive smoking and disease: a best-evidence synthesis. A report of the Working Group on Passive Smoking.

We reviewed the toxicologic, clinical, and epidemiologic evidence on the health effects of environmental tobacco smoke (ETS). For each type of exposure to environmental tobacco smoke we have sought articles in the English language reporting studies of effects on human health. Formal criteria that stressed study design, quality of execution and generalizability of results were used to select 116 scientifically admissible reports from over 2,900 articles. We concluded that: (a) there is strong evidence of an association between residential exposure to environmental tobacco smoke and both respiratory illness and reduction of lung function, and also between maternal smoking and reduced birth weight; (b) the weight of evidence is compatible with an association between active maternal smoking during pregnancy and increased infant mortality, and also between residential exposure to environmental tobacco smoke (primarily spousal smoking) and the risk of lung cancer; (c) there is evidence consistent with a relationship between exposure to environmental tobacco smoke in the workplace and respiratory symptoms, (d) the evidence is insufficient to implicate residential exposure to environmental tobacco smoke in relation to other forms of malignant disease or congenital malformations; (e) there is no evidence in the literature of an association between nonresidential exposure to environmental tobacco smoke and any form of cancer. Further studies are required to address the effects of exposure to environmental tobacco smoke, especially nonresidential exposure, in carcinogenesis and as a risk factor for atherosclerosis. Further work is also needed to improve measurement of exposure in such studies and to assess the importance of confounding factors.

Adolescent↗
PubMed1989

The public's health is too important to be left to public health workers. A commentary on Guide to Clinical Preventive Services.

Practicing physicians are the key to effective health promotion and disease prevention in their communities, according to the Guide to Clinical Preventive Services released in May by the United States Preventive Services Task Force. The Guide focuses on the clinical practitioner and strongly advocates integrating preventive activities into clinical practice. It also shows how required interventions can be done by the physician normally responsible for ongoing care. Case-finding is emphasized as a viable and desirable strategy in early detection of disease. The report also acknowledges behavioral and lifestyle components of risk factors for disease and the physician's opportunities to promote change in patients' risky behavior. We discuss the implications of including patient education and counseling in the physician's clinical armamentarium, highlighting changes in educational and health care delivery systems that can make such interventions work in preventive programs. The soundness of a best-evidence synthesis method to formulate recommendations and the use of a priori scientific rules to determine the effectiveness of many current and proposed preventive activities are hallmarks of the task force's approach to integrating science and clinical practice.

Canada↗
PubMed1989

Chronic exposure to sour gas emissions: meeting a community concern with epidemiologic evidence.

For 25 years residents of a rural area in southwestern Alberta have complained of health problems attributed to sour gas emissions from nearby natural gas refineries. We undertook a large epidemiologic study of the current health status and the selected morbidity rates among 2152 people in the exposed area. We established two comparison groups: one was a demographically similar unexposed population and the other a demographically different group also exposed to sour gas emissions in another region. The methods included a cross-sectional survey of current residents and separate historical cohort studies involving registry linkage to investigate cancer incidence and all-cause mortality. The cross-sectional survey involved a comprehensive health questionnaire, standardized clinical examinations by physicians blinded to the subjects' symptoms and concerns, and several laboratory tests. We were able to contact just under 60% of the people who we knew had moved from each area since 1958 and found no evidence of selective migration for health reasons. Although the residents of the exposed area reported an excess number of symptoms and health problems there were no significant differences in the mortality rate, incidence of cancer, reproductive problems, major ailments, hair levels of arsenic and certain metals or respiratory function between the groups.

Adolescent↗