Abstract:
RATIONALE:Recent cohort studies in chronic obstructive pulmonary disease (COPD) have questioned the validity of previously reported associations between inhaled corticosteroids (ICS) and reductions in mortality and rehospitalization in observational studies. Using time-dependent versions of statistical survival models, these studies have suggested immortal time bias as responsible for the proposed beneficial association. OBJECTIVES:We explored the extent of this bias in a study of patients with COPD monitored for a year from COPD discharge with two designs free of any immortal time bias in the General Practice Research Database in the United Kingdom. METHODS:In Design 1, we used only patients whose treatment status was defined on the same day of discharge to obtain a matched cohort based on propensity scores, which were derived from the patient-level baseline characteristics. In Design 2, we identified all in the study cohort who experienced death or rehospitalization and then matched each case to up to four noncases by randomly sampling from the cohort risk sets without regard to treatment status. MEASUREMENTS AND MAIN RESULTS:The propensity scores matched cohort analysis of 786 patients without a wait time found a significant risk reduction associated with use of ICS: hazard ratio, 0.69 (95% confidence interval, 0.52-0.93). The matched nested case-control analysis of 2,222 patients, designed without regard to exposure status and hence free of immortal time bias, gave a similar association with exposure to ICS in the last 6-month period: hazard ratio, 0.71 (0.56-0.90). CONCLUSIONS:We conclude that immortal time bias cannot account for the risk reduction associated with ICS exposure in observational studies.
journal_name
Am J Respir Crit Care Medauthors
Kiri VA,Pride NB,Soriano JB,Vestbo Jdoi
10.1164/rccm.200502-210OCkeywords:
subject
Has Abstractpub_date
2005-08-15 00:00:00pages
460-4issue
4eissn
1073-449Xissn
1535-4970pii
200502-210OCjournal_volume
172pub_type
杂志文章abstract:RATIONALE:Poor adherence is common in difficult-to-control asthma. Distinguishing patients with difficult-to-control asthma who respond to inhaled corticosteroids (ICS) from refractory asthma is an important clinical challenge. OBJECTIVES:Suppression of fractional exhaled nitric oxide (FeNO) with directly observed ICS...
journal_title:American journal of respiratory and critical care medicine
pub_type: 杂志文章
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abstract:RATIONALE:Patients of Hispanic origin with cystic fibrosis (CF) are the largest growing minority, representing 8.5% of patients with CF in the United States. No national survival analysis of this group has ever been undertaken. OBJECTIVES:We aimed to determine whether Hispanic ethnicity within the CF population is ass...
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journal_title:American journal of respiratory and critical care medicine
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doi:10.1164/ajrccm.150.1.8025770
更新日期:1994-07-01 00:00:00
abstract::E-selectin, an early mediator of leukocyte-endothelial adhesion, is expressed on activated endothelium. Soluble E-selectin is present in the supernatant of cytokine-activated endothelial cells and elevated serum levels are found in a variety of inflammatory conditions. We documented elevated E-selectin serum levels in...
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abstract::Genes for the chemokine receptors CCR5 and CCR2 are characterized by polymorphisms resulting in a nonfunctional receptor expression. Ligands for CCR2 and CCR5 (chemokines monocyte chemotactic protein-1 [MCP-1] and RANTES) are implicated in the pathogenesis of sarcoidosis. We have, therefore, analyzed polymorphisms of ...
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更新日期:2016-11-15 00:00:00
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更新日期:2003-09-15 00:00:00
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journal_title:American journal of respiratory and critical care medicine
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doi:10.1164/ajrccm.152.3.7663810
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更新日期:2013-04-01 00:00:00
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更新日期:1998-11-01 00:00:00
abstract::The German reunification offers a unique opportunity to study the impact of environmental factors on the development of childhood respiratory and allergic disorders in ethnically similar populations. We investigated the prevalence of asthma, hay fever, atopy, and bronchial hyperresponsiveness (BHR) in 9- to 11-year ol...
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更新日期:1995-06-01 00:00:00
abstract:RATIONALE:Outcome measures that integrate mortality and morbidity, like quality-adjusted life years (QALYs), have been proposed for critical care clinical trials. OBJECTIVES:We sought to describe the distribution of QALYs in critically ill patients and estimate sample size requirements for a hypothetical trial using Q...
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更新日期:2013-02-01 00:00:00
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pub_type: 临床试验,杂志文章,随机对照试验
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更新日期:1997-05-01 00:00:00
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pub_type: 杂志文章
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更新日期:2006-07-15 00:00:00
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journal_title:American journal of respiratory and critical care medicine
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更新日期:2011-03-01 00:00:00
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journal_title:American journal of respiratory and critical care medicine
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更新日期:2009-09-01 00:00:00
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journal_title:American journal of respiratory and critical care medicine
pub_type: 杂志文章,随机对照试验
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更新日期:2015-10-15 00:00:00