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Emphysema Findings Associated with Heavy Asbestos-Exposure in High Resolution Computed Tomography of Finnish Construction Workers

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Asbestos fibers are known to cause lung fibrosis, but their role in emphysema is unclear. We wanted to evaluate the relationship between asbestos exposure and emphysema by using high-resolution computed tomography (HRCT). Conventional and high resolution CT was performed on 600 smoking construction workers with an asbestos-related occupational disease. Emphysema subtypes (centrilobular, paraseptal, panlobular emphysema and bullae) were separately scored on a semiquantitative scale from 0 to 5, which scores were added up to yield the total emphysema score. Occupation, exposure duration, age, pack years and asbestosis diagnosis were analyzed in general linear models for possible associations with emphysema. The inter- (quadratic weighted kappa, kappa(qw)=0.46-0.72) and intraobserver (kappa(qw)=0.78-0.94) agreements for the subtype-scores and the reliability of the total score (Cronbach's alpha=0.87) were good. Insulators had a significantly higher paraseptal, panlobular and total score than the other occupational groups when adjusted for age and smoking. An asbestosis diagnosis was also a significant independent predictor of a higher total score. Emphysema was more common when workers had asbestosis or were heavily exposed to asbestos (insulators), but due to confounding factors the causative role of asbestos in emphysema needs further study.
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J Occup Health 2004; 46: 266–271
Journal of
Occupational Health
Emphysema Findings Associated with Heavy Asbestos-Exposure
in High Resolution Computed Tomography of Finnish
Construction Workers
Olli HUUSKONEN
1
, Leena KIVISAARI
2
, Anders ZITTING
1
, Simo KALEVA
1
and Tapio VEHMAS
1
1
Finnish Institute of Occupational Health and
2
Helsinki University Central Hospital, Department of Radiology,
Finland
Abstract: Emphysema Findings Associated with
Heavy Asbestos-Exposure in High Resolution
Computed Tomography of Finnish Construction
Workers: Olli H
UUSKONEN,
et al
. Finnish Institute of
Occupational Health, Helsinki, Finland—Asbestos
fibers are known to cause lung fibrosis, but their role in
emphysema is unclear. We wanted to evaluate the
relationship between asbestos exposure and
emphysema by using high-resolution computed
tomography (HRCT). Conventional and high resolution
CT was performed on 600 smoking construction
workers with an asbestos-related occupational disease.
Emphysema subtypes (centrilobular, paraseptal,
panlobular emphysema and bullae) were separately
scored on a semiquantitative scale from 0 to 5, which
scores were added up to yield the total emphysema
score. Occupation, exposure duration, age, pack years
and asbestosis diagnosis were analyzed in general
linear models for possible associations with
emphysema. The inter- (quadratic weighted kappa,
κ
qw
=0.46–0.72) and intraobserver (κ
qw
=0.78– 0.94)
agreements for the subtype-scores and the reliability
of the total score (Cronbach’s alpha=0.87) were good.
Insulators had a significantly higher paraseptal,
panlobular and total score than the other occupational
groups when adjusted for age and smoking. An
asbestosis diagnosis was also a significant
independent predictor of a higher total score.
Emphysema was more common when workers had
asbestosis or were heavily exposed to asbestos
(insulators), but due to confounding factors the
causative role of asbestos in emphysema needs further
study.
(J Occup Health 2004; 46: 266–271)
Received Nov 20, 2003; Accepted May 14, 2004
Correspondence to: T. Vehmas, Finnish Institute of Occupational
Health, Radiology Unit, Topeliuksenkatu 41 a A, FIN-00250
Helsinki, Finland
(e-mail: tapio.vehmas@occuphealth.fi)
Key words: Asbestosis, Lung diseases, Obstructive,
Occupational diseases, Occupational groups,
Tomography, X-ray computed
Construction workers are exposed to a variety of
inhaled agents that have adverse effects on the lungs,
e.g. mixed dusts containing silica, asbestos, quartz, man-
made fibers and various other building materials. It has
been established that occupational exposure to silica
causes pulmonary emphysema in addition to silicosis
1, 2)
.
Emphysema has also been associated with coal workers
pneumoconiosis
3)
. The main nonmalignant diseases
caused by asbestos exposure are pleural disorders and
interstitial lung fibrosis, leading eventually to asbestosis
4)
.
High resolution computed tomography has proven to
be more sensitive and reliable than chest radiography
especially in the early stages of emphysema
5–7)
. The
disease is visible as hypodense areas in the lung
parenchyme. Subtypes of emphysema can be
differentiated based on their appearance in HRCT.
Centrilobular emphysema is characterized by numerous
small lucencies predominantly in the upper lobes, whereas
in paraseptal emphysema the lucencies are found in
subpleural areas. Panlobular emphysema causes an
overall decrease in lung attenuation without focal
lucencies. Emphysematous bullae are seen as large,
sharply demarcated lucencies measuring at least 1 cm in
diameter
8)
. Of these subtypes centrilobular emphysema
is usually associated with cigarette smoking
9)
.
This study is part of a national asbestos program,
aiming to minimize all exposure to asbestos, to identify
people exposed occupationally and to improve the
diagnostics of asbestos-related diseases. We wanted to
work out the possible association of occupation and
asbestos exposure with HRCT findings of emphysema
in construction workers while adjusting for age and
smoking habit.
267Olli HUUSKONEN, et al.: HRCT Emphysema in Workers Exposed to Asbestos
Materials and Methods
Study subjects
The study subjects were identified in a previous study
among 18,900 Finnish persons exposed to asbestos
10)
. Out
of the 2,857 persons with an asbestos-related occupational
disease, those (600; 589 men and 11 women) living in
the Helsinki area, willing to participate, and with
sufficient data available formed the study group.
Inclusion criteria were asbestosis with or without smoking
(n=122, out of which 85 cases had been diagnosed at the
start of the primary study) or bilateral pleural plaques
without asbestosis and a history of smoking for at least
10 years (n=488). The mean age of the group was 64
(ranging from 38 to 81) yr. Most subjects had been
occupationally exposed to asbestos-containing materials
for over 20 (mean 26) yr and had smoked 24 packs a
year on average. Twenty subjects with asbestosis were
lifetime non-smokers.
All subjects were examined and interviewed personally
by an occupational physician. The interview was
structured and included questions on the subjects’
smoking habits and occupational history. Experts in the
assessment of asbestos exposure (an occupational
physician and an occupational hygienist) evaluated the
patients’ occupational histories and the subjects were
classified based on their main occupation (Table 1). The
groups were numbered according to the estimated
increasing asbestos-exposure (groups 1–5) based on an
asbestos screening study among Finnish construction
workers
10, 11)
. The group “Insulators”, who had worked
as asbestos sprayers and also at dismantling asbestos-
containing insulations, were estimated to have the
heaviest exposure. The subjects in the group “Others”
represented various occupational groups with
heterogeneous asbestos-exposure. Their predominant
occupational title was “construction site cleaner”.
The study group included 121 patients with asbestosis.
The diagnoses were based on the patient’s symptoms,
occupational history (sufficient exposure according to the
clinical experience at the Finnish Institute of Occupational
Health), a typical pattern in lung function tests (restriction
and impaired diffusion capacity) and a suggestive finding
of fibrosis in HRCT, and that other possible diseases were
excluded.
Imaging
Unenhanced spiral CT was performed for all exposed
workers with a Picker PQ 2000 scanner (Picker
International, USA) in the supine position and at full
inspiration from the apices to the costophrenic angle (125
mA, 140 kV, collimation 10 mm, pitch 1.5). The images
were reconstructed with a 10-mm slice thickness and a
standard algorithm and printed at two settings: window
width (WW) 1,000 Hounsfield units (HU) and window
level (WL) –700 HU for viewing the lung parenchyme
and WW 400 HU, WL 40 HU for the mediastinum and
pleura. In addition, 4–7 HRCT slices were scanned from
the aortic arch or pulmonary hila to the lung bases (200
mA, 130 kV, slice thickness 1,5 mm, WW 1,000 HU,
WL –700 HU). All imaging was performed with the
patient’s informed consent and permission from the local
ethical committee.
Image analysis
All images were reviewed by 3 experienced
radiologists (LK, TV and AZ) separately, blinded from
all clinical data, except from the patient’s name and date
of birth which were printed on the images. A structured
form was filled out at each reading considering pulmonary
emphysema (centrilobular, paraseptal and panlobular
emphysema and bullae). The findings were scored on an
arbitrary scale from 0 to 5, where 0 means no sign of
emphysema, 1 stands for slight and 5 for extreme
ehphysematous changes.
Fibrosis was also scored on an arbitrary scale from 0
to 5. The score was based on the signs of fibrosis in
HRCT, such as subpleural curvilinear opacities,
subpleural perpendicular lines, parenchymal bands and
honeycombing. This scale was reported in detail in an
earlier work by the authors
12)
.
A set of 43 (HR)CT examinations was double-read by
each observer to estimate intraobserver agreement. The
interval between the readings was at least one month.
Table 1. Characteristics of the patients enrolled in the study
Occupational group N
Age (years) Smoking (pack years) Exposure duration (years)
mean SD mean SD mean SD
1. Engineers 41 65.3 6.7 23.7 15.5 29.9 9.7
2. Electricians 52 57.9 6.2 20.3 13.4 24.3 9.3
3. Carpenters 129 64.9 7.3 23.9 14.3 28.1 8.6
4. Plumbers 74 60.2 7.4 23.1 14.6 26.7 10.8
5. Insulators 36 60.5 7.3 23.4 17.2 17.8 9.5
6. Others 268 63.0 7.1 24.4 15.5 25.3 9.4
268 J Occup Health, Vol. 46, 2004
Statistical analysis
The pooled observer agreement considering the
abovementioned emphysematous findings was evaluated
by quadratic weighted kappa (κ
qw
), which is equal to
intraclass correlation
13)
. CT findings with a κ
qw
>0.4 were
considered reliable and were used in further analyses.
After the κ
qw
-values were computed, the radiologists’
mean scores on both sides were used in further
computations.
A total variable, the emphysema total score (ranging
from 0 to 20), was calculated by adding together
individual scores considering emphysema variables.
Cronbach’s alpha (α)
13)
was used to study the reliability
of the method, i.e. how well the recorded different
radiological findings of emphysema reflect the same
disease. The closer the α-value is to 1 the better the
reliability is. A value of at least 0.7 was considered good.
General linear models were used to study the
relationships between the independent variables
(occupational group, age, pack years, the duration of
exposure and the asbestosis diagnosis) and the dependent
variables (HRCT emphysema total score and the
individual emphysema subtype scores). The analysis
begins with a preliminary model including all the
independent variables. The insignificant variables are
removed from the model through backward elimination,
aiming at the least possible number of significant
variables. The qualitative variables (occupational group
and asbestosis diagnosis) in the models were compared
to a chosen reference group (0-level) which other groups
were compared to (insulators and patients without
asbestosis, respectively). The analysis yields an estimate
of the change in the dependent variable resulting from a
change of one unit in the independent variable, and a
coefficient of determination (r
2
), which corresponds to
the proportion of the variance in the dependent variable
that is explained by the model.
All analyses were performed with SPSS statistical
software (Version 10.1, SPSS Inc. Chicago, IL, USA).
Results
The method
The quadratic weighted kappa (κ
qw
) -values describing
agreement are shown in Table 2. Intraobserver agreement
Table 2. Observer agreement
Emphysema type Inter-observer Intra-observer
Centrilobular 0.72 (0.69–0.74) 0.83 (0.78–0.97)
Paraseptal 0.68 (0.65–0.71) 0.94 (0.92–0.95)
Panlobular 0.46 (0.42–0.50) 0.78 (0.72–0.82)
Bullae 0.60 (0.57–0.64) 0.92 (0.89–0.94)
Quadratic weighted kappa, 95% confidence intervals in
parentheses
Table 3. Distribution of the emphysema subtype-scores*
)
in occupational groups
Occupational group
Engineers Electricians Carpenters Plumbers Insulators Others Total
Emphysema type
Centrilobular % % % % % % %
0 (<0.5) 75 88 81 85 72 80 81
1 (<1.5) 15 10 9 8 8 11 10
2 (<2.5) 10 2 6 4 8 7 6
3–5 (2.5) 0 0 3 3 11 3 3
Paraseptal
0 (<0.5) 85 94 89 92 75 88 88
1 (<1.5) 15 6 5 5 6 7 7
2 (<2.5) 0 0 4 3 11 3 3
3–5 (2.5) 0 0 2 0 8 2 2
Panlobular
0 (<0.5) 78 94 87 88 72 80 83
1 (<1.5) 20 4 10 11 14 15 13
2 (<2.5) 0 2 2 0 8 2 2
3–5 (2.5) 3 0 2 1 6 2 2
Bullae
0 (<0.5) 88 94 91 95 69 91 90
1 (<1.5) 12 4 5 5 25 7 7
2 (<2.5) 0 2 2 0 6 0 1
3–5 (2.5) 0 0 2 0 0 2 1
The scores are averages for 3 readers: 0 meaning < 0.5, 1 meaning 0.5 and < 1.5, etc.
269Olli HUUSKONEN, et al.: HRCT Emphysema in Workers Exposed to Asbestos
Fig. 1. Distribution of the HRCT emphysema total score in
the occupational groups.
individual emphysema types from the total score did not
improve reliability.
Findings
Most of the exposed workers had no sign of
emphysema visible in HRCT. The percentage of no
emphysema signs (i.e. two out of 3 radiologists had scored
the variable as 0, average score <0.5) ranged from 80 to
90 on average in the different subtypes of emphysema.
The emphysema findings grouped by occupation are
shown in Table 3. Regarding the total score, mild
emphysema (0.5 total score <4.5) was present in 29 %
of subjects in HRCT. Five percent had a more severe
disease (Fig. 1, Table 5). The crude total of emphysema
scores averaged 0.77 and 1.36 for those without and with
asbestosis diagnosis, respectively-
The general linear models showed significant
associations between the dependent variables (the
emphysema total score and the individual emphysema
subtypes) and the independent variables (Table 4). The
coefficient of determination was low in all models
(r
2
=0.04–0.11).
There was a significant positive correlation between
the emphysema and fibrosis scores (r
2
=0.10, p=0.014),
but the coefficient of determination was low (r
2
=0.009).
Pack years were a highly significant predictor of the
total score and all emphysema subtypes (p<0.001 in all
models). Asbestosis was also a significant predictor of
the total score (p=0.041), and centrilobular (p=0.040) and
paraseptal emphysema (p=0.018). Age and exposure
years showed a borderline significance at most.
Table 4. Relation between subtypes of emphysema and the independent variables: Insulators are used as a reference group
Dependent variables
Centrilobular Paraseptal Panlobular Bullae Sum score
Independent variables est. p est. p est. p est. p est. p
Occupational group 0.298 0.047 0.025 0.295 0.081
Engineers –0.21 0.179 –0.28 0.024 –0.18 0.17 –0.17 0.105 –0.81 0.067
Electricians –0.35 0.016 –0.36 0.002 –0.34 0.008 –0.18 0.071 –1.19 0.005
Carpenters –0.24 0.064 –0.25 0.014 –0.33 0.003 –0.11 0.208 –0.91 0.014
Plumbers –0.26 0.056 –0.33 0.003 –0.33 0.005 –0.21 0.028 –1.09 0.006
(0–level) Insulators 0 .. 0 .. 0 .. 0 .. 0 ..
Others –0.24 0.053 –0.25 0.01 –0.22 0.031 –0.15 0.074 –0.83 0.017
Age +0.007 0.007 +0.006 0.094 +0.02 0.134
Smoking (pack years) +0.012 0.0001 +0.008 0.0001 +0.005 0.001 +0.004 0.001 +0.03 0.0001
Exposure duration +0.002 0.237
Asbestosis +0.14 0.04 +0.13 0.018 +0.07 0.136 +0.41 0.041
r
2
0.11 0.09 0.05 0.04 0.1
est.: Estimate of the score in question, .. : Reference group (0–level), p-value does not apply. –: Variable not included in the model,
non-significant in preliminary models
was higher than interobserver agreement in all variables.
All κ
qw
-values were over 0.4 and significantly different
from 0.
The reliability of the emphysema total score as a
method was considered good (α=0.87). Deleting
270 J Occup Health, Vol. 46, 2004
Insulator worker had a higher total score on average
(mean=1.36, SE=0.20) that the other groups (mean=0.77,
SE=0.08). The occupational groups differed significantly
from each other considering the total score (p=0.017),
and paraseptal (p=0.010) and panlobular (p=0.031)
emphysema.
Discussion
In our material, emphysema was most common when
workers had asbestosis or were heavily exposed to
asbestos.
As expected, smoking was the strongest predictor of
emphysema in our study. According to the literature,
smoking is associated mainly with centrilobular
emphysema
9)
. In our material this association was not so
clear; smoking was associated with all emphysema
subtypes. Also, patients with diagnosed asbestosis had a
significantly higher emphysema total score than those
without the disease, but there was an excess of
emphysema in workers with heavy asbestos-exposure
(insulators), which was not explained by the
abovementioned factors or advancing age.
Our subjects were a sample of Finnish construction
workers already diagnosed with an asbestos-related
disease of the lungs or pleura. We found signs of
emphysema in one third of our subjects, as could be
expected, since the majority had a smoking history of
over 20 pack years. This was due to smoking being one
of the inclusion criteria for the original study
14)
aiming to
screen for lung cancer in asbestos exposed workers. The
subjects were adjusted for smoking in our general linear
models by adding pack years as an independent variable.
Thus, other possible causes of emphysema could be
assessed in the models.
High tube currents were used in imaging in order to
achieve optimal image quality. This was considered
essential for imaging small and slender changes in lungs
that had been distorted by asbestos-related disease.
The emphysema total score was considered
reproducible and reliable. Agreement was high and all
subtypes of emphysema were scored consistently by each
reader. All variables were considered essential to the
score since deleting individual variables did not improve
the reliability of the method
15)
.
The prevalence of emphysema in this study was
somewhat higher than in some earlier studies. Oksa et
al.
16)
reported 5 out of 21 asbestos sprayers (24%) with
signs of emphysema in HRCT. Bégin et al.
1)
studied an
emphysema index in 207 workers exposed to mineral
dusts. The findings were scored from 0 to 4 based on the
presence, type and extent of emphysema in 6 lung zones
and then added together to yield the index. The method
was regarded as easy to use and 2 out of 3 readers agreed
in 63 % of the cases considering emphysema (κ=0.44 for
the entire index). The average score was 0.56 (SE=0.09)
among patients with asbestosis and 0.21 (SE=0.4) among
those without the disease. Jarad et al.
7)
introduced a
method analogous to the ILO classification of chest
radiographs [scale: 0/– (0) to 3/4 (11) in 6 lung zones]
using 24 HRCT slices. Agreement was higher in HRCT
than in chest radiography (92% vs. 78% respectively).
All subjects (60 asbestos workers) had some signs of
emphysema; the median score being 18/66. These
findings are similar to ours, but the prevalence of
emphysema in these studies is greater. The two latter
methods seem rather lengthy, and the radiation dose in
the work of Jarad et al.
7)
is considerable.
The general linear models confirmed the significant
association of smoking with the severity of emphysema.
The emphysema scores were highest among insulator
workers, who have the heaviest exposure to asbestos.
Even though differences between occupational groups are
partly caused by individual variation, it seems that
asbestos-exposure may play a significant role in causing
emphysema.
In earlier studies, emphysema has been associated
especially with silicosis and coal workers’
pneumoconiosis
1–3)
. Our data indicated a significant
Table 5. Distribution of the HRCT emphysema total score*
)
among the occupational groups
Occupational group
Engineers Electricians Carpenters Plumbers Insulators Others
Emphysema total score % % % % % %
0607669705663
1181415191418
21045567
3–4 10 6 6 3 6 7
5–10 3 0 0 0 19 3
11–20 0 0 2 0 0 2
The scores are averages for 3 readers: 0 meaning <0.5, 1 meaning 0.5 and <1.5, etc.
271Olli HUUSKONEN, et al.: HRCT Emphysema in Workers Exposed to Asbestos
association between heavy asbestos-exposure and
asbestosis with emphysema. The possible (and probable)
exposure to silica or other dusts was not possible to define
in this study.
There are possible confounding factors that must be
kept in mind. The fibrosis in asbestosis causes shrinking
and scarring of the lung, which may result in cicatricial
emphysema. This might explain the slight, but significant
correlation between the emphysema and fibrosis scores.
Emphysema is also associated with chronic bronchitis
caused by smoking. This may result in a “dirty lung” in
chest radiography and be mistaken for fibrosis. Chronic
bronchitis and emphysema also impair lung function,
which may also lead to a false diagnosis of asbestosis,
both in lung function tests and in radiological
examinations.
In conclusion, we found an excess of emphysema in
workers with heavy exposure to asbestos and in patients
with asbestosis, but the causative role of asbestos in
emphysema requires further investigation.
Acknowledgments: The authors wish to thank Mr.
Kristian Taskinen for his contribution to the statistical
modeling of the data, and Dr. Hannu Lehtola for the
patient interviews. We wish to thank Dr. Antti
Tossavainen for his expertise in occupational hygiene and
epidemiology.
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Objective: the aim of this study was to evaluate the association between interstitial lung abnormalities, asbestos exposure and age in a population of retired workers previously occupationally exposed to asbestos. Methods: previously occupationally exposed former workers to asbestos eligible for a survey conducted between 2003 and 2005 in four regions of France, underwent chest CT examinations and pulmonary function testing. Industrial hygienists evaluated asbestos exposure and calculated for each subject a cumulative exposure index (CEI) to asbestos. Smoking status information was also collected in this second round of screening. Expert radiologists performed blinded independent double reading of chest CT-scans and classified interstitial lung abnormalities into: no abnormality, minor interstitial findings, interstitial findings inconsistent with UIP, possible or definite UIP. In addition, emphysema was assessed visually (none, minor: emphysema <25%, moderate: between 25 and 50% and severe: >50% of the lung). Logistic regression models adjusted for age and smoking were used to assess the relationship between interstitial lung abnormalities and occupational asbestos exposure. Results: the study population consisted of 2157 male subjects. Interstitial lung abnormalities were present in 365 (16.7%) and emphysema in 444 (20.4%). Significant positive association was found between definite or possible UIP pattern and age (OR adjusted =1.08 (95% CI: 1.02-1.13)). No association was found between interstitial abnormalities and CEI or the level of asbestos exposure. Conclusion: presence of interstitial abnormalities at HRCT was associated to aging but not to cumulative exposure index in this cohort of former workers previously occupationally exposed to asbestos.
... For instance, coal and gold miners have been found to have a higher prevalence of emphysema compared with control groups [5]. The emphysema score measured by QCT has been associated with construction workers who are heavily exposed to asbestos [6] but not quartz and silica [7,8]. Many previous studies have been limited regarding fully understanding the effects of dust exposure because they employed only one or a few imaging variables for a small number of subjects. ...
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Background: Dust exposure has been reported as a risk factor of pulmonary disease, leading to alterations of segmental airways and parenchymal lungs. This study aims to investigate alterations of quantitative computed tomography (QCT)-based airway structural and functional metrics due to cement-dust exposure. Methods: To reduce confounding factors, subjects with normal spirometry without fibrosis, asthma and pneumonia histories were only selected, and a propensity score matching was applied to match age, sex, height, smoking status, and pack-years. Thus, from a larger data set (N = 609), only 41 cement dust-exposed subjects were compared with 164 non-cement dust-exposed subjects. QCT imaging metrics of airway hydraulic diameter (Dh), wall thickness (WT), and bifurcation angle (θ) were extracted at total lung capacity (TLC) and functional residual capacity (FRC), along with their deformation ratios between TLC and FRC. Results: In TLC scan, dust-exposed subjects showed a decrease of Dh (airway narrowing) especially at lower-lobes (p < 0.05), an increase of WT (wall thickening) at all segmental airways (p < 0.05), and an alteration of θ at most of the central airways (p < 0.001) compared with non-dust-exposed subjects. Furthermore, dust-exposed subjects had smaller deformation ratios of WT at the segmental airways (p < 0.05) and θ at the right main bronchi and left main bronchi (p < 0.01), indicating airway stiffness. Conclusions: Dust-exposed subjects with normal spirometry demonstrated airway narrowing at lower-lobes, wall thickening at all segmental airways, a different bifurcation angle at central airways, and a loss of airway wall elasticity at lower-lobes. The airway structural alterations may indicate different airway pathophysiology due to cement dusts.
... For instance, coal and gold miners have been found to have a higher prevalence of emphysema compared with control groups (5). The emphysema score measured by QCT has been associated with construction workers who are heavily exposed to asbestos (6) but not quartz and silica (7,8). Many previous studies have been limited regarding fully understanding the effects of dust exposure because they employed only one or a few imaging variables for a small number of subjects. ...
Preprint
Full-text available
Background: Dust exposure has been reported as a risk factor of pulmonary disease, leading to alterations of segmental airways and parenchymal lungs. This study aims to investigate alterations of quantitative computed tomography (QCT)-based airway structural and functional metrics due to cement-dust exposure. Methods: To reduce confounding factors, subjects with normal spirometry without fibrosis, asthma and pneumonia histories were only selected, and a propensity score matching was applied to match age, sex, height, smoking status, and pack-years. Thus, from a larger data set (N=609), only 41 cement dust-exposed subjects were compared with 164 non-cement dust-exposed subjects. QCT imaging metrics of airway hydraulic diameter (Dh), wall thickness (WT), and bifurcation angle (θ) were extracted at total lung capacity (TLC) and functional residual capacity (FRC), along with their deformation ratios between TLC and FRC. Results: In TLC scan, dust-exposed subjects showed a decrease of Dh (airway narrowing) especially at lower-lobes (p<0.05), an increase of WT (wall thickening) at all segmental airways (p<0.05), and an alteration of θ at most of the central airways (p<0.001) compared with non-dust-exposed subjects. Furthermore, dust-exposed subjects had smaller deformation ratios of WTat the segmental airways (p<0.05) and θ at the right main bronchi and left main bronchi (p<0.01), indicating airway stiffness. Conclusions: Dust-exposed subjects with normal spirometry demonstrated airway narrowing at lower-lobes, wall thickening at all segmental airways, a different bifurcation angle at central airways, and a loss of airway wall elasticity at lower-lobes. The airway structural alterations may indicate different airway pathophysiology due to cement dusts.
... For instance, coal and gold miners have been found to have a higher prevalence of emphysema compared with control groups (5). The emphysema score measured by QCT has been associated with construction workers who are heavily exposed to asbestos (6) but not quartz and silica (7,8). Many previous studies have been limited regarding fully understanding the effects of dust exposure because they employed only one or a few imaging variables for a small number of subjects. ...
Preprint
Full-text available
Background Dust exposure has been reported as a risk factor of pulmonary disease, leading to alterations of segmental airways and parenchymal lungs. This study aims to investigate alterations of quantitative computed tomography (QCT)-based airway structural and functional metrics due to cement-dust exposure. Methods To reduce confounding factors, subjects with normal spirometry without asthma and pneumonia histories were only selected, and a propensity score matching was applied to match age, sex, height, and smoking status. Thus, from a larger data set (N=609), only 46 cement dust-exposed subjects were compared with 184 non-cement dust-exposed subjects. QCT imaging metrics of airway hydraulic diameter ( D h ), wall thickness (WT), and bifurcation angle ( θ ) were extracted at total lung capacity (TLC) and functional residual capacity (FRC), along with their deformation ratios between TLC and FRC. Results In TLC scan, dust-exposed subjects showed a decrease of D h (airway narrowing) especially at lower-lobes ( p <0.05), an increase of WT (wall thickening) at all segmental airways ( p <0.05), and an alteration of θ at most of the central airways ( p <0.001) compared with non-dust-exposed subjects. Furthermore, dust-exposed subjects had smaller deformation ratios of WT at the segmental airways ( p <0.05) and θ at the right main bronchi and left main bronchi ( p <0.001), indicating airway stiffness. Conclusions Dust-exposed subjects with normal spirometry demonstrated airway narrowing at lower-lobes, wall thickening at all segmental airways, a different bifurcation angle at central airways, and a loss of airway wall elasticity at lower-lobes. The airway structural alterations may indicate different airway pathophysiology due to cement dusts.
... fréquent chez les travailleurs atteints d'asbestose, ou qui ont été exposés à une forte exposition à l'amiante. Cependant, l'auteur a conclu que les anomalies obser- vées pourraient être la conséquence d'autres expositions, en particulier de la silice, ce qui expliquerait les cas d'emphysème retrouvés[9]. Notre étude faite sur 367 personnes exposées au chrysotile, 20 (54,45%) montre que la BPCO est significativement associée à l'asbestose (p : 0,032, OR : 0,713). Cette constatation est en accord avec les conclu- sions de certains auteurs dont Belayneh A Abeja[10], qui, dans une étude réalisée en 2010, a comparé 277 travailleurs exposés au chrysotile avec 177 travailleurs non exposés. ...
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Déterminer la prévalence et les facteurs de risque de maladies dues à l’amiante dans une entreprise de fabrication d’amiante-ciment. Matériel et méthode : Il s’agit d’une étude rétrospective réalisée en 2010 après la fermeture définitive de l’entreprise de fabrication de fibrociment. L’étude a été réalisée sur dossiers médicaux de 367 personnes en contact de l’amiante (principalement du chrysotile). Au moment de l’étude, ces travailleurs avaient un âge moyen de 57,87 ± 10,54 ans (min : 25 max : 85 ans). Leur durée d’exposition est de 21,14 ans ± 5,88 (min 2 ans, max : 30 ans). L’exposition moyenne aux fibres d’amiante était de 14,01 fibres / ml / années ± 21,53 (min : 0,11 max : 106,31). 36,2% fument des cigarettes, avec en moyenne de 9,3 paquets-années ± 21,53 (min : 0 max : 60). L’étude statistique a été faite sur le logiciel SPSS 20 (test du Chi carré et régression logistique binaire). Résultats : 253 personnes (68,93%) présentent une pathologie liée à l’exposition professionnelle à l’amiante. La pathologie la plus fréquente est représentée par la fibrose interstitielle diffuse (42,0%) suivie par les plaques pleurales calcifiées (9,8%), l’épaississement pleural (6,8%), la bronchopneumopathie chronique obstructive (5,44%), l’atélectasie ronde (1,4%) et la pleurésie (0,5%). Le cancer du poumon et le mésothéliome représentent respectivement 1,1% et 1,9% des pathologies diagnostiquées. Ils apparaissent pour des durées d’exposition > 20 ans (min : 20,75, max 22,29) et pour des concentrations de 20,31 et 18,36 fibres / ml / années. Le diagnostic de ces tumeurs a été fait lors d’un examen radiologique réalisé dans un autre contexte clinique. Mots clés : amiante, pathologies dues à l’amiante, la fibrose interstitielle, maladies pulmonaires obstructives chroniques, mésothéliome, épaississement pleural, plaques pleurales. Objective : To determine the prevalence and risk factors of diseases due to asbestos at a manufacturing company of asbestos-cement. Material and method : It’s a retrospective study done in 2007 after the final closure of the plant fiber cement. The study was made on medical files of 367 people who worked in contact with asbestos (mainly chrysotile) for an average of 21.14 years ± 5.88. At the time of the study (2007), these workers had a mean age of 57.87 years ± 10.54 (min : 25 max : 85). Their exposure time is 21.14 years ± 5.88 (min 2 years, max : 30 years). The average exposure to asbestos fibers is 14.01 fibers / ml / years ± 21.53 (min : 0.11 max : 106.31). 36.2% smoke cigarettes, with an average 9.3 pack-years ± 21.53 (min : 0 max : 60).The statistical study made by SPSS 17. (Chi square test, binary logistic regression). Results : 253 people (68.93%) present pathology in relation to the professional exposure. The most frequent pathology is represented by the diffuse interstitial fibrosis (42.0%) followed by the calcified pleural plaques (9.8%), pleural thickening (6.8%), the chronic obstructive pulmonary disease (COPD) (5.44%), the round atelectasis (1,4%) and the pleurisy (0,5%). Lung cancer and mesothelioma are respectively 1.1 % and 1.9 % of the diagnosed pathology. They appear for exposure times > 20 years (min : 20.75 max 22.29) and for concentrations of 20.31 and 18.36 fibers/ml/years. The diagnosis of these tumors was made fortuitously during a radiological examination.
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Objectives: This study was conducted to explore the association between pneumoconiosis and pneumothorax. Design: Retrospective cohort study. Setting: Nationwide population-based study using the Taiwan National Health Insurance Database. Participants: A total of 2333 pneumoconiosis patients were identified (1935 patients for propensity score (PS)-matched cohort) and matched to 23 330 control subjects by age and sex (7740 subjects for PS-matched cohort). Primary and secondary outcome measures: The incidence and the cumulative incidence of pneumothorax. Results: Both incidence and the cumulative incidence of pneumothorax were significantly higher in the pneumoconiosis patients as compared with the control subjects (p<0.0001). For multivariable Cox regression analysis adjusted for age, sex, residency, income level and other comorbidities, patients with pneumoconiosis exhibited a significantly higher risk of pneumothorax than those without pneumoconiosis (HR 3.05, 95% CI 2.18 to 4.28, p<0.0001). The male sex, heart disease, peripheral vascular disease, chronic pulmonary disease and connective tissue disease were risk factors for developing pneumothorax in pneumoconiosis patients. Conclusions: Our study revealed a higher risk of pneumothorax in pneumoconiosis patients and suggested potential risk factors in these patients. Clinicians should be aware about the risk of pneumothorax in pneumoconiosis patients.
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Objectif : Déterminer la prévalence et les facteurs de risque de maladies dues à l’amiante dans une entreprise de fabrication d’amiante-ciment. Matériel et méthode : Il s’agit d’une étude rétrospective réalisée en 2010 après la fermeture définitive de l’entreprise de fabrication de fibrociment. L’étude a été réalisée sur dossiers médicaux de 367 personnes en contact de l’amiante (principalement du chrysotile). Au moment de l’étude, ces travailleurs avaient un âge moyen de 57,87 ± 10,54 ans (min : 25 max : 85 ans). Leur durée d’exposition est de 21,14 ans ± 5,88 (min 2 ans, max : 30 ans). L’exposition moyenne aux fibres d’amiante était de 14,01 fibres / ml / années ± 21,53 (min : 0,11 max : 106,31). 36,2% fument des cigarettes, avec en moyenne de 9,3 paquets-années ± 21,53 (min : 0 max : 60). L’étude statistique a été faite sur le logiciel SPSS 20 (test du Chi carré et régression logistique binaire). Résultats : 253 personnes (68,93%) présentent une pathologie liée à l’exposition professionnelle à l’amiante. La pathologie la plus fréquente est représentée par la fibrose interstitielle diffuse (42,0%) suivie par les plaques pleurales calcifiées (9,8%), l’épaississement pleural (6,8%), la bronchopneumopathie chronique obstructive (5,44%), l’atélectasie ronde (1,4%) et la pleurésie (0,5%). Le cancer du poumon et le mésothéliome représentent respectivement 1,1% et 1,9% des pathologies diagnostiquées. Ils apparaissent pour des durées d’exposition > 20 ans (min : 20,75, max 22,29) et pour des concentrations de 20,31 et 18,36 fibres / ml / années. Le diagnostic de ces tumeurs a été fait lors d’un examen radiologique réalisé dans un autre contexte clinique. Mots clés : amiante, pathologies dues à l’amiante, la fibrose interstitielle, maladies pulmonaires obstructives chroniques, mésothéliome, épaississement pleural, plaques Pleurales Objective : To determine the prevalence and risk factors of diseases due to asbestos at a manufacturing company of asbestos-cement. Material and method : It’s a retrospective study done in 2007 after the final closure of the plant fiber cement .The study was made on medical files of 367 people who worked in contact with asbestos (mainly chrysotile) for an average of 21.14 years ± 5.88. At the time of the study (2007), these workers had a mean age of 57.87 years ± 10.54 (min : 25 max : 85). Their exposure time is 21.14 years ± 5.88 (min 2 years, max : 30 years). The average exposure to asbestos fibers is 14.01 fibers / ml / years ± 21.53 (min : 0.11 max : 106.31). 36.2% smoke cigarettes, with an average 9.3 pack-years ± 21.53 (min : 0 max : 60).The statistical study made by SPSS 17. (Chi square test, binary logistic regression). Results : 253 people (68.93%) present pathology in relation to the professional exposure. The most frequent pathology is represented by the diffuse interstitial fibrosis (42.0%) followed by the calcified pleural plaques (9.8%), pleural thickening (6.8%), the chronic obstructive pulmonary disease (COPD) (5.44%), the round atelectasis (1,4%) and the pleurisy (0,5%). Lung cancer and mesothelioma are respectively 1.1 % and 1.9 % of the diagnosed pathology. They appear for exposure times > 20 years (min : 20.75 max 22.29) and for concentrations of 20.31 and 18.36 fibers/ml/years. The diagnosis of these tumors was made fortuitously during a radiological examination.
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Article Many quantities of interest in medicine, such as anxiety or degree of handicap, are impossible to measure explicitly. Instead, we ask a series of questions and combine the answers into a single numerical value. Often this is done by simply adding a score from each answer. For example, the mini-HAQ is a measure of impairment developed for patients with cervical myelopathy.1 This has 10 items (table 1)) recording the degree of difficulty experienced in carrying out daily activities. Each item is scored from 1 (no difficulty) to 4 (can't do). The scores on the 10 items are summed to give the mini-HAQ score. View this table:View PopupView InlineTable 1 Mini-HAQ scale in 249 severely impaired subjects When items are used to form a scale they need to have internal consistency. The items should all measure the same thing, so they should be correlated with one another. A useful coefficient for assessing internal consistency is Cronbach's alpha.2 The formula is: [This figure is not available.] where k is the number of items, si2 is the variance of the ith item and sT2 is the variance of the total score formed by summing all the items. If the items are not simply added to make the score, but first multiplied by weighting coefficients, we multiply the item by its coefficient before calculating the variance si2. Clearly, we must have at least two items-that is k >1, or will be undefined. The coefficient works because the variance of the sum of a group of independent variables is the sum of their variances. If the variables are positively correlated, the variance of the sum will be increased. If the items making up the score are all identical and so perfectly correlated, all the si2 will be equal and sT2 = k2 si2, so that si2/sT2 = 1/k and = 1. On the other hand, if the items are all independent, then sT2 = si2 and = 0. Thus will be 1 if the items are all the same and 0 if none is related to another. For the mini-HAQ example, the standard deviations of each item and the total score are shown in the table. We have si2 = 11.16, sT2 = 77.44, and k = 10. Putting these into the equation, we have [This figure is not available.] which indicates a high degree of consistency. For scales which are used as research tools to compare groups, may be less than in the clinical situation, when the value of the scale for an individual is of interest. For comparing groups, values of 0.7 to 0.8 are regarded as satisfactory. For the clinical application, much higher values of are needed. The minimum is 0.90, and =0.95, as here, is desirable. In a recent example, McKinley et al devised a questionnaire to measure patient satisfaction with calls made by general practitioners out of hours.3 This included eight separate scores, which they interpreted as measuring constructs such as satisfaction with communication and management, satisfaction with doctor's attitude, etc. They quoted for each score, ranging from 0.61 to 0.88. They conclude that the questionnaire has satisfactory internal validity, as five of the eight scores had >0.7. In this issue Bosma et al report similar values, from 0.67 to 0.84, for assessments of three characteristics of the work environment.4 Cronbach's alpha has a direct interpretation. The items in our test are only some of the many possible items which could be used to make the total score. If we were to choose two random samples of k of these possible items, we would have two different scores each made up of k items. The expected correlation between these scores is . References1.↵Casey ATH, Crockard HA, Bland JM, Stevens J, Moskovich R, Ransford AO.Development of a functional scoring system for rheumatoid arthritis patients with cervical myelopathy Ann Rheum Dis (in press).2.↵Cronbach LJ.Coefficient alpha and the internal structure of tests.Psychometrika1951; 16:297–333.3.↵McKinley RK, Manku Scott T, Hastings AM, French DP, Baker R.Reliability and validity of a new measure of patient satisfaction with out of hours primary medical care in the United Kingdom: development of a patient questionnaire.BMJ1997; 314:193–8.OpenUrlFREE Full Text4.↵Bosma H, Marmot MG, Hemingway H, Nicholson AC, Brunner E, Stansfield SA.Low job control and risk of coronary heart disease in Whitehall II (prospective cohort) study.BMJ1997; 314:558–65.
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High-resolution CT, a technique that optimizes the spatial resolution of lung parenchyma, uses thin collimation, reconstruction with a high-spatial frequency algorithm, image targeting, and sometimes increased kVp and mA settings. Performing a high-resolution CT study can provide information regarding lung morphology that cannot be obtained using conventional CT or plain radiographs. Alterations in anatomy can be identified at the level of the secondary pulmonary lobule, and although often nonspecific, in certain situations high-resolution CT findings can be diagnostic. High-resolution CT scanning is also helpful in identifying patients who have significant lung disease despite a normal chest radiograph, and in planning biopsy procedures.
Article
It has been established that coal pneumoconiosis and confluent silicosis are associated with emphysematous changes in the lungs. In the present study, we addressed the concept of emphysema in simple silicosis and asbestosis and in workers exposed to these minerals without the pneumoconiosis. The study was done on 207 consecutive workers evaluated for possible pneumoconiosis at Québec Workman Compensation Board, who had a radiographic reading of pneumoconiosis in the category 0 or 1 of the ILO scale, and in 5 control subjects. Emphysema was detected, typed, and graded on high-resolution CT scans by three independent experienced readers. Age, work experience and industry, smoking habits, and pulmonary function test results were analyzed for possible associations. The subjects were 59 +/- 1 years of age and had mineral dust exposure averaging 26 +/- 1 years; 31 were lifetime nonsmokers and the others were either ex- or current smokers. Ninety-six workers were from primary and 111 from secondary industries and did not differ in any parameter. The CT scan readings for emphysema yielded a 63% complete agreement. In lifetime non-smokers, emphysema was seen in 1 of 20 subjects without pneumoconiosis but in 8 of 11 patients with pneumoconioses. In smokers without pneumoconioses, emphysema was present in 55% of patients with silica exposure, but 29% of patients with asbestos exposure but comparable smoking (p = 0.04). Emphysema type was equally distributed among the groups except for more paracicatricial type in confluent silicosis. Regression analyses documented that age, smoking, exposure type, and presence of pneumoconiosis were significant contribution factors. In the workers without pneumoconiosis, age, smoking, and exposure type (silica) were significant. Emphysema related best with FEV1/FVC ratio, MMEF, and DCO reductions. The prevalence of abnormality of FEV1/FVC ratio was two to five times normal and that of reduced DCO two times normal. We conclude that, in our population, there was a significant excess of CT scan emphysema, associated with lung dysfunction, in those with pneumoconioses and in smokers with silica exposure. In the absence of smoking, it took a patient with pneumoconiosis to have emphysema. These changes contributed to the lung function impairment of these subjects with ILO category 0 or 1 pneumoconioses.