scispace - formally typeset
Search or ask a question
Author

Walter O. Spitzer

Bio: Walter O. Spitzer is an academic researcher from McGill University. The author has contributed to research in topics: Cohort study & Asthma. The author has an hindex of 34, co-authored 99 publications receiving 5467 citations. Previous affiliations of Walter O. Spitzer include McMaster University & University of Potsdam.
Topics: Cohort study, Asthma, Desogestrel, Cohort, Population


Papers
More filters
Journal ArticleDOI
13 Jan 1996-BMJ
TL;DR: Risks of venous thromboembolism was slightly increased in users of third generation oral contraceptives compared with users of second generation products and the need for clinical prudence is indicated but doctors and women seeking contraception should exercise informed choice.
Abstract: Objective: To test whether use of combined oral contraceptives containing third generation progestogens is associated with altered risk of venous thromboembolism. Design: Matched case-control study. Setting: 10 centres in Germany and United Kingdom. Subjects: Cases were 471 women aged 16-44 who had a venous thromboembolism. Controls were 1772 women (at least 3 controls per case) unaffected by venous thromboembolism who were matched with corresponding case for age and for hospital or community setting. Main outcome measures: Odds ratios derived with stratified analyses and unconditional logistic regression to adjust for potential confounding variables. Results: Odds ratios (95% confidence intervals) for venous thromboembolism were: for any oral contraceptives versus no use, 4.0 (3.1 to 5.3); for second generation products (low dose ethinyloestradiol, no gestodene or desogestrel) versus no use, 3.2 (2.3 to 4.3); for third generation products (low dose ethinyloestradiol, gestodene or desogestrel) versus no use, 4.8 (3.4 to 6.7); for third generation products versus second generation products, 1.5 (1.1 to 2.1); for products containing gestodene versus second generation products, 1.5 (1.0 to 2.2); and for products containing desogestrel versus second generation products, 1.5 (1.1 to 2.2). Probability of death due to venous thromboembolism for women using third generation products is about 20 per million users per year, for women using second generation products it is about 14 per million users per year, and for non-users it is five per million per year. Conclusions: Risk of venous thromboembolism was slightly increased in users of third generation oral contraceptives compared with users of second generation products. Key messages Key messages This case-control study examined risk of venous thromboembolism associated with different types of oral contraceptive Overall, there was a fourfold higher relative risk of thromboembolism associated with current use of any oral contraceptive versus no current use The risk of thromboembolism was 1.5 times higher for third generation contraceptives compared with second generation products Our data indicate the need for clinical prudence but allow doctors and women seeking contraception to exercise informed choice

540 citations

Journal ArticleDOI
TL;DR: A randomized controlled trial was conducted to assess the effects of substituting nurse practitioners for physicians in primary-care practice, and the quality of care rendered seemed similar, as assessed by a quantitative "indicator-condition" approach.
Abstract: From July, 1971, to July, 1972, in a large suburban Ontario practice of two family physicians, a randomized controlled trial was conducted to assess the effects of substituting nurse pract...

421 citations

Journal ArticleDOI
TL;DR: This paper examines the question of asthma and non-asthma mortality using data from the entire cohort of 12,301 users of asthma drugs followed during the period 1980 through 1987 and finds that the risk of asthma death began to escalate drastically at about 1.4 canisters per month of inhaled beta-agonist, the recommended limit.
Abstract: The association between the use of inhaled beta-agonists and the risk of death and near-death from asthma has previously been reported. It was based on a nested case-control study of 129 cases and 655 control subjects selected from a cohort of 12,301 users of asthma drugs followed during the period 1980 through 1987. In this paper we examine the question of asthma and non-asthma mortality using data from the entire cohort of 12,301 asthmatics. There were 46 asthma and 134 non-asthma deaths in this cohort, for which there were 47,842 person-years of follow-up. The overall rate of asthma death was 9.6 per 10,000 asthmatics per year. This rate varied significantly according to the use of fenoterol, albuterol, or oral corticosteroids in the prior 12 months and the number of asthma hospitalizations in the prior 2 years. The rate decreased significantly, by 0.6 asthma deaths per 10,000 asthmatics per year over the study period, after controlling for the effect of the four other risk factors. It also increased significantly with the use of all beta-agonists, and more so for fenoterol than for albuterol, although this difference was partly explained by the dose inequivalence of the two drugs. Change-point dose-response curves showed that the risk of asthma death began to escalate drastically at about 1.4 canisters (of 20,000 micrograms each) per month of inhaled beta-agonist, the recommended limit. For non-asthma death, the overall rate of 28 deaths per 10,000 asthmatics per year was not related to the use of inhaled beta-agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

371 citations

Journal ArticleDOI
23 Dec 1992-JAMA
TL;DR: Data support recent guidelines from several countries that recommend the use of inhaled corticosteroids in moderate and severe asthma.
Abstract: Objective. —To examine the relationship between patterns of use of inhaled beclomethasone dipropionate and the risk of fatal and near-fatal asthma. Design. —Nested case-control analysis of a historical cohort; a further analysis. Setting. —The 12 301 residents of Saskatchewan aged 5 to 54 years who were dispensed 10 or more asthma drugs from 1978 to 1987. Patients. —The 129 persons who experienced asthma death (n=44) and near-death (n=85) and their 655 controls matched as to age and date of entry into the cohort, with the additional matching criteria of at least one hospitalization for asthma in the prior 2 years, region of residence, and having received social assistance. Main Outcome. —Life-threatening attacks of asthma defined as death due to asthma or the occurrence of hypercarbia, intubation, and mechanical ventilation during an acute attack of asthma. Results. —After accounting for the risk associated with use of other medications and adjustment for markers of risk of adverse events related to asthma, subjects who had been dispensed, on average, one or more metered-dose inhalers of beclomethasone per month over a 1-year period had a significantly lower risk of fatal and near-fatal asthma (odds ratio, 0.1; 95% confidence interval, 0.02 to 0.6). Conclusion.—These data support recent guidelines from several countries that recommend the use of inhaled corticosteroids in moderate and severe asthma. ( JAMA . 1992;268:3462-3464)

283 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this review the usual methods applied in systematic reviews and meta-analyses are outlined, and the most common procedures for combining studies with binary outcomes are described, illustrating how they can be done using Stata commands.

31,656 citations

Journal ArticleDOI
TL;DR: It is recommended that spirometry is required for the clinical diagnosis of COPD to avoid misdiagnosis and to ensure proper evaluation of severity of airflow limitation.
Abstract: Chronic obstructive pulmonary disease (COPD) remains a major public health problem. It is the fourth leading cause of chronic morbidity and mortality in the United States, and is projected to rank fifth in 2020 in burden of disease worldwide, according to a study published by the World Bank/World Health Organization. Yet, COPD remains relatively unknown or ignored by the public as well as public health and government officials. In 1998, in an effort to bring more attention to COPD, its management, and its prevention, a committed group of scientists encouraged the U.S. National Heart, Lung, and Blood Institute and the World Health Organization to form the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Among the important objectives of GOLD are to increase awareness of COPD and to help the millions of people who suffer from this disease and die prematurely of it or its complications. The first step in the GOLD program was to prepare a consensus report, Global Strategy for the Diagnosis, Management, and Prevention of COPD, published in 2001. The present, newly revised document follows the same format as the original consensus report, but has been updated to reflect the many publications on COPD that have appeared. GOLD national leaders, a network of international experts, have initiated investigations of the causes and prevalence of COPD in their countries, and developed innovative approaches for the dissemination and implementation of COPD management guidelines. We appreciate the enormous amount of work the GOLD national leaders have done on behalf of their patients with COPD. Despite the achievements in the 5 years since the GOLD report was originally published, considerable additional work is ahead of us if we are to control this major public health problem. The GOLD initiative will continue to bring COPD to the attention of governments, public health officials, health care workers, and the general public, but a concerted effort by all involved in health care will be necessary.

17,023 citations

Journal ArticleDOI
TL;DR: In this article, cross-sectional data from the Medical Outcomes Study (MOS) were analyzed to test the validity of the MOS 36-Item Short-Form Health Survey (SF-36) scales as measures of physical and mental health constructs.
Abstract: Cross-sectional data from the Medical Outcomes Study (MOS) were analyzed to test the validity of the MOS 36-Item Short-Form Health Survey (SF-36) scales as measures of physical and mental health constructs. Results from traditional psychometric and clinical tests of validity were compared. Principal

8,553 citations

Journal ArticleDOI
12 Oct 2016-BMJ
TL;DR: Risk of Bias In Non-randomised Studies - of Interventions is developed, a new tool for evaluating risk of bias in estimates of the comparative effectiveness of interventions from studies that did not use randomisation to allocate units or clusters of individuals to comparison groups.
Abstract: Non-randomised studies of the effects of interventions are critical to many areas of healthcare evaluation, but their results may be biased. It is therefore important to understand and appraise their strengths and weaknesses. We developed ROBINS-I (“Risk Of Bias In Non-randomised Studies - of Interventions”), a new tool for evaluating risk of bias in estimates of the comparative effectiveness (harm or benefit) of interventions from studies that did not use randomisation to allocate units (individuals or clusters of individuals) to comparison groups. The tool will be particularly useful to those undertaking systematic reviews that include non-randomised studies.

8,028 citations