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Li F, Choi J, Zhang X, Rajaraman PK, Lee CH, Ko H, Chae KJ, Park EK, Comellas AP, Hoffman EA, Lin CL. Characterizing Subjects Exposed to Humidifier Disinfectants Using Computed-Tomography-Based Latent Traits: A Deep Learning Approach. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:11894. [PMID: 36231196 PMCID: PMC9565839 DOI: 10.3390/ijerph191911894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Around nine million people have been exposed to toxic humidifier disinfectants (HDs) in Korea. HD exposure may lead to HD-associated lung injuries (HDLI). However, many people who have claimed that they experienced HD exposure were not diagnosed with HDLI but still felt discomfort, possibly due to the unknown effects of HD. Therefore, this study examined HD-exposed subjects with normal-appearing lungs, as well as unexposed subjects, in clusters (subgroups) with distinct characteristics, classified by deep-learning-derived computed-tomography (CT)-based tissue pattern latent traits. Among the major clusters, cluster 0 (C0) and cluster 5 (C5) were dominated by HD-exposed and unexposed subjects, respectively. C0 was characterized by features attributable to lung inflammation or fibrosis in contrast with C5. The computational fluid and particle dynamics (CFPD) analysis suggested that the smaller airway sizes observed in the C0 subjects led to greater airway resistance and particle deposition in the airways. Accordingly, women appeared more vulnerable to HD-associated lung abnormalities than men.
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Affiliation(s)
- Frank Li
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
- IIHR—Hydroscience & Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Jiwoong Choi
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA 52242, USA
- Department of Internal Medicine, School of Medicine, University of Kansas, Kansas City, KS 66045, USA
| | - Xuan Zhang
- IIHR—Hydroscience & Engineering, University of Iowa, Iowa City, IA 52242, USA
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Prathish K. Rajaraman
- IIHR—Hydroscience & Engineering, University of Iowa, Iowa City, IA 52242, USA
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Chang-Hyun Lee
- Department of Radiology, University of Iowa, Iowa City, IA 52242, USA
- Department of Radiology, College of Medicine, Seoul National University, Seoul 100-011, Korea
| | - Hongseok Ko
- Department of Radiology, Kangwon National University Hospital, Chuncheon 200-010, Korea
| | - Kum-Ju Chae
- Department of Radiology, Jeonbuk National University Hospital, Jeonju 560-011, Korea
| | - Eun-Kee Park
- Department of Medical Humanities and Social Medicine, College of Medicine, Kosin University, Busan 600-011, Korea
| | | | - Eric A. Hoffman
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
- Department of Radiology, University of Iowa, Iowa City, IA 52242, USA
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Ching-Long Lin
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
- IIHR—Hydroscience & Engineering, University of Iowa, Iowa City, IA 52242, USA
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA 52242, USA
- Department of Radiology, University of Iowa, Iowa City, IA 52242, USA
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Li F, Choi J, Zou C, Newell JD, Comellas AP, Lee CH, Ko H, Barr RG, Bleecker ER, Cooper CB, Abtin F, Barjaktarevic I, Couper D, Han M, Hansel NN, Kanner RE, Paine R, Kazerooni EA, Martinez FJ, O'Neal W, Rennard SI, Smith BM, Woodruff PG, Hoffman EA, Lin CL. Latent traits of lung tissue patterns in former smokers derived by dual channel deep learning in computed tomography images. Sci Rep 2021; 11:4916. [PMID: 33649381 PMCID: PMC7921389 DOI: 10.1038/s41598-021-84547-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 02/15/2021] [Indexed: 11/30/2022] Open
Abstract
Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease and the traditional variables extracted from computed tomography (CT) images may not be sufficient to describe all the topological features of lung tissues in COPD patients. We employed an unsupervised three-dimensional (3D) convolutional autoencoder (CAE)-feature constructor (FC) deep learning network to learn from CT data and derive tissue pattern-clusters jointly. We then applied exploratory factor analysis (EFA) to discover the unobserved latent traits (factors) among pattern-clusters. CT images at total lung capacity (TLC) and residual volume (RV) of 541 former smokers and 59 healthy non-smokers from the cohort of the SubPopulations and Intermediate Outcome Measures in the COPD Study (SPIROMICS) were analyzed. TLC and RV images were registered to calculate the Jacobian (determinant) values for all the voxels in TLC images. 3D Regions of interest (ROIs) with two data channels of CT intensity and Jacobian value were randomly extracted from training images and were fed to the 3D CAE-FC model. 80 pattern-clusters and 7 factors were identified. Factor scores computed for individual subjects were able to predict spirometry-measured pulmonary functions. Two factors which correlated with various emphysema subtypes, parametric response mapping (PRM) metrics, airway variants, and airway tree to lung volume ratio were discriminants of patients across all severity stages. Our findings suggest the potential of developing factor-based surrogate markers for new COPD phenotypes.
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Affiliation(s)
- Frank Li
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
- IIHR-Hydroscience and Engineering, 2406 Seamans Center for the Engineering Art and Science, University of Iowa, Iowa City, IA, 52242, USA
| | - Jiwoong Choi
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA
- Department of Internal Medicine, School of Medicine, University of Kansas, Kansas City, KS, USA
| | - Chunrui Zou
- IIHR-Hydroscience and Engineering, 2406 Seamans Center for the Engineering Art and Science, University of Iowa, Iowa City, IA, 52242, USA
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA
| | - John D Newell
- Department of Radiology, University of Iowa, Iowa City, IA, USA
| | | | - Chang Hyun Lee
- Department of Radiology, University of Iowa, Iowa City, IA, USA
- Department of Radiology, Seoul National University, Seoul, Republic of Korea
| | - Hongseok Ko
- Department of Radiology, Chungnam National University Sejong Hospital, Sejong, Republic of Korea
| | - R Graham Barr
- Mailman School of Public Health, Columbia University, New York, NY, USA
| | | | | | | | | | - David Couper
- Department of Biostatistics, University of North Carolina, Chapel Hill, NC, USA
| | - MeiLan Han
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Robert Paine
- School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Ella A Kazerooni
- Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | | | - Wanda O'Neal
- School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Stephen I Rennard
- Department of Internal Medicine, University of Nebraska College of Medicine, Omaha, NE, USA
| | - Benjamin M Smith
- Department of Medicine, Columbia University, New York, NY, USA
- Research Institute, McGill University Health Center, Montreal, Canada
| | | | - Eric A Hoffman
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
- Department of Radiology, University of Iowa, Iowa City, IA, USA
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Ching-Long Lin
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA.
- IIHR-Hydroscience and Engineering, 2406 Seamans Center for the Engineering Art and Science, University of Iowa, Iowa City, IA, 52242, USA.
- Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA.
- Department of Radiology, University of Iowa, Iowa City, IA, USA.
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Castaldi PJ, San José Estépar R, Mendoza CS, Hersh CP, Laird N, Crapo JD, Lynch DA, Silverman EK, Washko GR. Distinct quantitative computed tomography emphysema patterns are associated with physiology and function in smokers. Am J Respir Crit Care Med 2013; 188:1083-90. [PMID: 23980521 PMCID: PMC3863741 DOI: 10.1164/rccm.201305-0873oc] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Emphysema occurs in distinct pathologic patterns, but little is known about the epidemiologic associations of these patterns. Standard quantitative measures of emphysema from computed tomography (CT) do not distinguish between distinct patterns of parenchymal destruction. OBJECTIVES To study the epidemiologic associations of distinct emphysema patterns with measures of lung-related physiology, function, and health care use in smokers. METHODS Using a local histogram-based assessment of lung density, we quantified distinct patterns of low attenuation in 9,313 smokers in the COPDGene Study. To determine if such patterns provide novel insights into chronic obstructive pulmonary disease epidemiology, we tested for their association with measures of physiology, function, and health care use. MEASUREMENTS AND MAIN RESULTS Compared with percentage of low-attenuation area less than -950 Hounsfield units (%LAA-950), local histogram-based measures of distinct CT low-attenuation patterns are more predictive of measures of lung function, dyspnea, quality of life, and health care use. These patterns are strongly associated with a wide array of measures of respiratory physiology and function, and most of these associations remain highly significant (P < 0.005) after adjusting for %LAA-950. In smokers without evidence of chronic obstructive pulmonary disease, the mild centrilobular disease pattern is associated with lower FEV1 and worse functional status (P < 0.005). CONCLUSIONS Measures of distinct CT emphysema patterns provide novel information about the relationship between emphysema and key measures of physiology, physical function, and health care use. Measures of mild emphysema in smokers with preserved lung function can be extracted from CT scans and are significantly associated with functional measures.
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Affiliation(s)
- Peter J. Castaldi
- Channing Division of Network Medicine
- Division of General Medicine, and
| | | | | | - Craig P. Hersh
- Channing Division of Network Medicine
- Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Nan Laird
- Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts; and
| | | | - David A. Lynch
- Department of Radiology, National Jewish Health, Denver, Colorado
| | - Edwin K. Silverman
- Channing Division of Network Medicine
- Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - George R. Washko
- Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
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Yilmaz C, Dane DM, Patel NC, Hsia CC. Quantifying heterogeneity in emphysema from high-resolution computed tomography: a lung tissue research consortium study. Acad Radiol 2013; 20:181-93. [PMID: 23122057 DOI: 10.1016/j.acra.2012.09.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 08/29/2012] [Accepted: 09/03/2012] [Indexed: 10/27/2022]
Abstract
RATIONALE AND OBJECTIVES To quantify spatial distribution of emphysema using high-resolution computed tomography (HRCT), we applied semiautomated analysis with internal attenuation calibration to measure regional air volume, tissue volume, and fractional tissue volume (FTV = tissue/[air + tissue] volume) in well-characterized patients studied by the Lung Tissue Research Consortium (LTRC). METHODS HRCT was obtained at supine end-inspiration and end-expiration, and prone end-inspiration from 31 patients with mild, moderate, severe, or very severe emphysema (stages II-V, forced expiratory volume at 1 second >75%, 51%-75%, 21%-50% and ≤20% predicted, respectively). Control data were from 20 healthy non-smokers (stage I). Each lobe was analyzed separately. Heterogeneity of FTV was assessed from coefficients of variation (CV) within and among lobes, and the kurtosis and skewness of FTV histograms. RESULTS In emphysema, lobar air volume increased up to 177% above normal except in the right middle lobe. Lobar tissue volume increased up to 107% in mild-moderate stages then normalized in advanced stages. Normally, FTV was up to 82% higher in lower than upper lobes. In mild-moderate emphysema, lobar FTV increased by up to 74% above normal at supine inspiration. In severe emphysema, FTV declined below normal in all lobes and positions in correlation with pulmonary function (P < .05). Markers of FTV heterogeneity increased steadily with disease stage in correlation with pulmonary function (P < .05); the pattern is distinct from that seen in interstitial lung disease (ILD). CONCLUSION CT-derived biomarkers differentiate the spatial patterns of emphysema distribution and heterogeneity from that in ILD. Early emphysema is associated with elevated tissue volume and FTV, consistent with hyperemia, inflammation or atelectasis.
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Wang Z, Gu S, Leader JK, Kundu S, Tedrow JR, Sciurba FC, Gur D, Siegfried JM, Pu J. Optimal threshold in CT quantification of emphysema. Eur Radiol 2012; 23:975-84. [PMID: 23111815 DOI: 10.1007/s00330-012-2683-z] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 08/24/2012] [Accepted: 08/30/2012] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine the optimal threshold by quantitatively assessing the extent of emphysema at the level of the entire lung and at the level of individual lobes using a large, diverse dataset of computed tomography (CT) examinations. METHODS This study comprises 573 chest CT examinations acquired from subjects with different levels of airway obstruction (222 none, 83 mild, 141 moderate, 63 severe and 64 very severe). The extent of emphysema was quantified using the percentage of the low attenuation area (LAA%) divided by the total lung or lobe volume(s). The correlations between the extent of emphysema, and pulmonary functions and the five-category classification were assessed using Pearson and Spearman's correlation coefficients, respectively. When quantifying emphysema using a density mask, a wide range of thresholds from -850 to -1,000 HU were used. RESULTS The highest correlations of LAA% with the five-category classification and PFT measures ranged from -925 to -965 HU for each individual lobe and the entire lung. However, the differences between the highest correlations and those obtained at -950 HU are relatively small. CONCLUSION Although there are variations in the optimal cut-off thresholds for individual lobes, the single threshold of -950 HU is still an acceptable threshold for density-based emphysema quantification.
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Affiliation(s)
- Zhimin Wang
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Shirtcliffe P, Marsh S, Travers J, Weatherall M, Beasley R. Childhood asthma and GOLD-defined chronic obstructive pulmonary disease. Intern Med J 2010; 42:83-8. [PMID: 20403069 DOI: 10.1111/j.1445-5994.2010.02238.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Current understanding of chronic obstructive pulmonary disease (COPD) is that it results from an interaction of genetic and environmental factors. This study aimed to investigate the strength of association of various known risk factors for COPD. METHODS Detailed written questionnaires, full pulmonary function tests and atopy testing were completed in 749 people, aged 25-75 years, recruited from a random population sample. COPD was defined, using Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, as a post-bronchodilator forced expiratory volume in 1 s/forced vital capacity (FEV(1) /FVC) ratio <0.7. RESULTS The prevalence of COPD was higher in men (OR 1.7 (95% CI 1.1-2.7)) and increased with increasing age (OR per decade older 2.1 (95% CI 1.7-2.7)). COPD was more frequent in current and ex-smokers and increased with increasing pack years (OR per 10 pack years 1.3 (95% CI 1.1-1.5)). On a logit scale, a diagnosis of asthma as a child conferred a similar risk as an increase in age of 22 years or 62 pack years of cigarette smoking. CONCLUSION Childhood asthma emerged with the strongest association for GOLD-defined COPD. Possible explanations for this are suggested, including limitations of the current GOLD spirometric definition of COPD, a chance observation because of the high prevalence of both disorders in this population, or alternatively childhood asthma is a risk factor for COPD.
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Affiliation(s)
- P Shirtcliffe
- Medical Research Institute of New Zealand, Wellington, New Zealand.
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Shirtcliffe P, Weatherall M, Marsh S, Travers J, Hansell A, McNaughton A, Aldington S, Muellerova H, Beasley R. COPD prevalence in a random population survey: a matter of definition. Eur Respir J 2007; 30:232-9. [PMID: 17666557 PMCID: PMC2516341 DOI: 10.1183/09031936.00157906] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A recent American Thoracic Society and European Respiratory Society joint Task Force report recommends using a lower limit of normal (LLN) of forced expiratory volume in one second/forced vital capacity as opposed to a fixed ratio of <0.7 to diagnose airflow obstruction, in order to reduce false positive diagnoses of chronic obstructive pulmonary disease (COPD) as defined by the Global Initiative for Obstructive Lung Disease (GOLD). To date, there is no reliable spirometry-based prevalence data for COPD in New Zealand and the effect of different definitions of airflow obstruction based on post-bronchodilator spirometry is not known. Detailed written questionnaires, full pulmonary function tests (including pre- and post-bronchodilator flow-volume loops) and atopy testing were completed in 749 subjects recruited from a random population sample. The GOLD-defined, age-adjusted prevalence (95% confidence interval) for adults aged >or=40 yrs was 14.2 (11.0-17.0)% compared with an LLN-defined, age-adjusted, post-bronchodilator prevalence in the same group of 9.0 (6.7-11.3)%. The prevalence of chronic obstructive pulmonary disease varied markedly depending on the definition used. Further research using longitudinal rather than cross-sectional data will help decide the preferred approach in chronic obstructive pulmonary disease prevalence surveys.
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Affiliation(s)
| | - Mark Weatherall
- Wellington School of Medicine & Health Sciences, Wellington, New Zealand
| | - Suzanne Marsh
- Medical Research Institute of New Zealand, Wellington, New Zealand
| | - Justin Travers
- Medical Research Institute of New Zealand, Wellington, New Zealand
| | | | | | - Sarah Aldington
- Medical Research Institute of New Zealand, Wellington, New Zealand
| | | | - Richard Beasley
- Medical Research Institute of New Zealand, Wellington, New Zealand
- University of Southampton, United Kingdom
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Marsh S, Aldington S, Williams MV, Weatherall M, Robiony-Rogers D, Jones D, Beasley R. Pulmonary function testing in New Zealand: the use and importance of reference ranges. Respirology 2007; 12:367-74. [PMID: 17539840 DOI: 10.1111/j.1440-1843.2007.01071.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND OBJECTIVES The diagnosis, assessment and management of a wide range of respiratory diseases rely on accurate interpretation of lung function tests through the use of reference equations to generate predicted values. This paper ascertains the suitability of reference equations currently used in New Zealand through comparison with newly derived equations from the Wellington Respiratory Survey, and discusses the relevance of the findings to the Asia Pacific region. METHODS A survey of lung function testing facilities determined the reference equations in common usage. Pulmonary function test results from healthy, lifelong non-smoking subjects (n = 180) were expressed as percentage predicted values, with comparisons made between the currently used and Wellington Respiratory Survey reference equations. Differences in disease severity classification in subjects with COPD (n = 46) and asthma (n = 61) were determined, using the different reference equations. RESULTS Currently used equations significantly underpredict measured values for FEV(1), PEF, TLC and RV by up to 20%. Severity classification of COPD and asthma based on per cent predicted FEV(1) was substantially altered by the choice of reference equation. CONCLUSION Many reference equations in current usage in New Zealand are no longer suitable for use. The applicability of reference equations used in other populations and countries within the Asia Pacific region requires further investigation. We recommend that up-to-date reference equations are derived and implemented if those currently used are shown to be unsatisfactory.
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Affiliation(s)
- Suzanne Marsh
- Medical Research Institute of New Zealand, Wellington, New Zealand
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Aldington S, Williams M, Nowitz M, Weatherall M, Pritchard A, McNaughton A, Robinson G, Beasley R. Effects of cannabis on pulmonary structure, function and symptoms. Thorax 2007; 62:1058-63. [PMID: 17666437 PMCID: PMC2094297 DOI: 10.1136/thx.2006.077081] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Cannabis is the most widely used illegal drug worldwide. Long-term use of cannabis is known to cause chronic bronchitis and airflow obstruction, but the prevalence of macroscopic emphysema, the dose-response relationship and the dose equivalence of cannabis with tobacco has not been determined. METHODS A convenience sample of adults from the Greater Wellington region was recruited into four smoking groups: cannabis only, tobacco only, combined cannabis and tobacco and non-smokers of either substance. Their respiratory status was assessed using high-resolution CT (HRCT) scanning, pulmonary function tests and a respiratory and smoking questionnaire. Associations between respiratory status and cannabis use were examined by analysis of covariance and logistic regression. RESULTS 339 subjects were recruited into the four groups. A dose-response relationship was found between cannabis smoking and reduced forced expiratory volume in 1 s to forced vital capacity ratio and specific airways conductance, and increased total lung capacity. For measures of airflow obstruction, one cannabis joint had a similar effect to 2.5-5 tobacco cigarettes. Cannabis smoking was associated with decreased lung density on HRCT scans. Macroscopic emphysema was detected in 1/75 (1.3%), 15/92 (16.3%), 17/91 (18.9%) and 0/81 subjects in the cannabis only, combined cannabis and tobacco, tobacco alone and non-smoking groups, respectively. CONCLUSIONS Smoking cannabis was associated with a dose-related impairment of large airways function resulting in airflow obstruction and hyperinflation. In contrast, cannabis smoking was seldom associated with macroscopic emphysema. The 1:2.5-5 dose equivalence between cannabis joints and tobacco cigarettes for adverse effects on lung function is of major public health significance.
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Affiliation(s)
- Sarah Aldington
- Medical Research Institute of New Zealand, P O Box 10055, Wellington 6143, New Zealand
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Travers J, Marsh S, Aldington S, Williams M, Shirtcliffe P, Pritchard A, Weatherall M, Beasley R. Reference ranges for exhaled nitric oxide derived from a random community survey of adults. Am J Respir Crit Care Med 2007; 176:238-42. [PMID: 17478616 DOI: 10.1164/rccm.200609-1346oc] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Measurement of the fraction of nitric oxide in exhaled breath (Fe(NO)) has been proposed as a noninvasive marker of airway inflammation. Before the widespread use of this test, there is a need to develop reference ranges to allow clinicians to interpret Fe(NO) measurements. OBJECTIVES To derive reference ranges for Fe(NO) and to determine which factors in health and disease influence Fe(NO) levels. METHODS Subjects aged between 25 and 75 years were drawn from a random sample of the predominantly white population of Wellington, New Zealand. MEASUREMENTS AND MAIN RESULTS Fe(NO) was measured using an online nitric oxide monitor in accordance with international guidelines. A detailed respiratory questionnaire and pulmonary function tests were performed. The geometric mean Fe(NO) was 17.9 parts per billion (ppb) with a 90% confidence interval for an individual prediction (reference range) for normal subjects of 7.8 to 41.1 ppb. Sex, atopy, and smoking status significantly affected Fe(NO) levels, and several reference ranges are presented adjusting for these factors. Asthma and allergic rhinitis were associated with higher Fe(NO). Measurement of Fe(NO) had poor discriminant ability to identify steroid-naive subjects with asthma. CONCLUSIONS The reference ranges presented may be used to assist in the interpretation of Fe(NO) measurements in white adults.
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Affiliation(s)
- Justin Travers
- Medical Research Institute of New Zealand, Wellington, New Zealand
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12
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Marsh S, Aldington S, Williams MV, Nowitz MR, Kingzett-Taylor A, Weatherall M, Shirtcliffe PM, McNaughton AA, Pritchard A, Beasley R. Utility of lung density measurements in the diagnosis of emphysema. Respir Med 2007; 101:1512-20. [PMID: 17307350 DOI: 10.1016/j.rmed.2007.01.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 11/16/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND The role of computerised tomography (CT) lung density measurements in objective quantification of emphysema is uncertain. The aim of this study was to determine normal reference values for CT lung density measurements and investigate their utility in identifying subjects with clinical emphysema. METHODS Normal subjects (non-smokers, no respiratory disease, n=185) and subjects with clinical emphysema (post-bronchodilator FEV(1)/FVC <70%, > or =10 pack years tobacco smoking, no childhood asthma and, either D(LCO)/VA <80% predicted and/or macroscopic emphysema on CT, n=22) were identified from a random population survey. Subjects underwent CT scanning, with measurement of areas of low attenuation as a percentage of total area (RA%) for three standardised slices and two reconstruction algorithms with a density threshold of -950 HU. Reference values in normal subjects, and ability of the measurements to discriminate between the two groups were determined. RESULTS Reference values for individual subjects showed wide confidence intervals (standard resolution scans, RA% females 0.2-3.9%, males 0.4-8.7%.) Subjects with emphysema had greater RA% values compared with normal subjects, the difference being most marked in apical slices (standard resolution algorithm, apical slice, median RA% 2.9% (95% CI 0.4-11.1%) vs. 0.1% (95% CI 0.0-0.5%), emphysema vs. normal subjects, respectively). Logistic regression analysis showed poor discriminant ability to distinguish between the groups, the most favourable cut-off yielding a sensitivity and specificity of 83.3% and 62.8%, respectively. CONCLUSIONS CT lung density measurements cannot reliably detect the presence of emphysema in an individual. We recommend further investigation into lung density measurements before their widespread use in clinical practice.
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Affiliation(s)
- Suzanne Marsh
- Medical Research Institute of New Zealand, P.O. Box 10055, Wellington, New Zealand
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Travers J, Marsh S, Caldwell B, Williams M, Aldington S, Weatherall M, Shirtcliffe P, Beasley R. External validity of randomized controlled trials in COPD. Respir Med 2006; 101:1313-20. [PMID: 17113277 DOI: 10.1016/j.rmed.2006.10.011] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2004] [Revised: 10/04/2006] [Accepted: 10/07/2006] [Indexed: 11/17/2022]
Abstract
BACKGROUND COPD is a heterogeneous disease comprising a wide range of clinical phenotypes, depending on the degree to which emphysema, chronic bronchitis, reversible bronchospasm and small airways inflammation are present. Not all of these phenotypes may be represented among the subjects included in randomized controlled drug trials (RCTs) in COPD, making it difficult for doctors to know to what extent RCT evidence applies to individual patients. From a respiratory health survey of adults randomly selected from the community, we have estimated the proportion of subjects with COPD who would have been eligible for inclusion in major COPD RCTs. METHODS A postal survey was sent to 3500 randomly selected individuals aged 25-75 years. Respondents were invited to complete a detailed respiratory questionnaire and pulmonary function tests. Subjects with COPD defined by post-bronchodilator spirometry were assessed against the eligibility criteria of 18 major RCTs cited in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. FINDINGS Of 749 subjects completing the full survey, 117 had COPD. Of these, a median of 5% (range 0-20%) of subjects met inclusion criteria for the major RCTs. Of 55 subjects with COPD receiving treatment, 0-9% (median 5%) met inclusion criteria for the major RCTs. INTERPRETATION The major COPD RCTs on which the GOLD treatment guidelines are based may have limited external validity. Over 90% of the COPD subjects in the community who were taking medication, did so on the basis of RCTs for which they would not have been eligible.
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Affiliation(s)
- Justin Travers
- Medical Research Institute of New Zealand, Wellington, New Zealand
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Travers J, Marsh S, Williams M, Weatherall M, Caldwell B, Shirtcliffe P, Aldington S, Beasley R. External validity of randomised controlled trials in asthma: to whom do the results of the trials apply? Thorax 2006; 62:219-23. [PMID: 17105779 PMCID: PMC2117157 DOI: 10.1136/thx.2006.066837] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Asthma is a heterogeneous disease with a wide range of clinical phenotypes, not all of which may be encompassed in the subjects included in randomised controlled trials (RCTs). This makes it difficult for clinicians to know to what extent the evidence derived from RCTs applies to a given patient. AIM To calculate the proportion of individuals with asthma who would have been eligible for the major asthma RCTs from the data of a random community survey of respiratory health. METHODS A postal survey was sent to 3500 randomly selected individuals aged 25-75 years. Respondents were invited to complete a detailed respiratory questionnaire and pulmonary function testing. Participants with current asthma were assessed against the eligibility criteria of the 17 major asthma RCTs cited in the Global Initiative for Asthma (GINA) guidelines. FINDINGS A total of 749 participants completed the full survey, of whom 179 had current asthma. A median 4% of participants with current asthma (range 0-36%) met the eligibility criteria for the included RCTs. A median 6% (range 0-43%) of participants with current asthma on treatment met the eligibility criteria. INTERPRETATION This study shows that the major asthma RCTs on which the GINA guidelines are based may have limited external validity as they have been performed on highly selected patient populations. Most of the participants with current asthma on treatment in the community would not have been eligible for these RCTs.
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Affiliation(s)
- Justin Travers
- Medical Research Institute of New Zealand, PO Box 10055, Wellington, New Zealand
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