www.asthma-workplace.com. program: cihr centers for research development: understanding/addressing...
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www.asthma-workplace.com
Program: CIHR Centers for Research Development:
Understanding/Addressing Physico-Social Environment, Financial partners:
IRSST and Lung Associations of Canada and of Québec
13 researchers of various disciplines of UdM and McGill,as well as scientific (IRSST) and strategic partners(Québec CSST and WCBs of Atlantic provinces,
Montreal Public Health)
Annual budget of 400 000 $ (2003-2009)for supporting 1) studentships and fellowships, 2) initiation
of projects (7/yr) and 3) continuous education of health professionals
See details on website: www.asthma-workplace.com
Acknowledgements and thanks
The Canadian Occupational Health Nurses Association and the Occupational Health Nurses Association of Nova Scotia.
The organizers of this meeting.
Mme Sylvie Daigle, coordinator of the Center for Asthma in the Workplace.
Lecturers and coordinators of workshops.
And all attendees !
General aim
Inform and motivate health professionals on the importance of
reducing referral delays in order to improve the prognosis
of occupational asthma.
Specific aims
Explain the nature of the problem.
Identify causal agents.
Describe investigational tools.
Be informed on the different steps to be included
in surveillance programs and in assessing specific workers.
Know on the natural history and persistence.
Asthma in the workplace:General considerations
Jean-Luc Malo MD,professor, Université de Montréal,chest physician, clinical researcher,Hôpital du Sacré-Cœur de Montréal
Supported by:Instituts canadiens de recherche en santéInstitut Robert-Sauvé en santé et sécuritédu travail du Québec (IRSST)L’Association pulmonaire du Canadaet l’Association pulmonaire du Québec
Suggested references
1. Book
Bernstein IL, Chan-Yeung M, Malo JL, Bernstein DI. Asthma in the Workplace. New
York, Francis & Taylor 2006.
2. Summary article
Malo JL, Chan-Yeung M. Occupational asthma. Journal of Allergy & Clin Immunol
2001; 108:317-328.
3. Series
Controversies in occupational asthma. Six articles in the Eur Respir J 2003
UptoDate : four articles
Proceedings of the first and second Jack Pepys Occupational Asthma Symposium.
Am J Respir Crit Care Med 2003 ; 167 : 450-471; An ATS/ERS Report:
100 key questions and needs in occupational asthma. Eur Respir J 2006; 27:607-614.
4. WEB sites
Asthma in the workplace Center: asthma-workplace.com
CSST : asthme.csst.qc.ca/
1. Definitions
2. Frequency and risk factors
3. Mechanisms
4. Identification and diagnosis
5. Medicolegal aspects
6. As a model for asthma
Asthma in the workplace
Asthma in the workplace
Asthma caused bythe workplace
(occupational asthma)
With a latencyperiod
Without alatency period
« Irritant-induced asthma »or
« Reactive airwaysdysfunction syndrome »
Asthma exacerbatedby the workplace
Variantsof asthma
ex: eosinophilicbronchitis;
“potroom asthma”
“Occupational asthma is a disease characterized by variable airflow limitation and/or hyperresponsiveness and/or inflammation due to causes and conditions attributable to a particular occupational environment and not to stimuli encountered outside the workplace.”
Editors of Asthma in the Workplace: Bernstein IL,Chan-Yeung M, Malo JL, Bernstein DI, 3rd ed.
Definition of occupational asthma
Confirmation of the “causal” relationship :
changes in airway caliber (~ 20%) ±changes in bronchial responsiveness±induction of airway inflammation
(control asthmatic subjects do not react)
Occupational asthmawith a latency period
Occupational asthmawithout a latency period
(“irritant-induced asthma”)
Diagnosis based on the history : inhalation accident withacute respiratory symptoms.
Possibility of several “less intense” inhalation accidents.
What does “without a latency” mean ?
Asthma exacerbated at work
Symptomatic status exacerbated at work.
How to document it with objective means ?
How to differentiate this condition from occupational asthma ?
1. Definitions
2. Frequency and risk factors
3. Mechanisms
4. Identification and diagnosis
5. Medicolegal aspects
6. As a model for asthma
Asthma in the workplace
Frequency of asthma in the workplace
1. Meta-analysis: ~ 9% of adult-onset asthmatic subjects report that their
asthma is worse at work ( Blanc P, 1999)
2. Prevalence in the general population:
surveys in general populations and answer to the following question :
is your asthma worse at work, better at weekends and in vacation ?
5-35 % of adult asthmatic subjects answer yes
(studies in Spain, Europe and several countries)
3. Prevalence in adult-onset asthmatic subjects seen
in a tertiary care hospital clinic : 15 % (Tarlo et al. 1999)
4. Sentinel-based projects:
SWORD (UK), SENSOR (USA), OBSERVATOIRE (France)
PROPULSE (Québec) : 10-100 / million workers
5. Medicolegal statistics:
Finland (175 / million workers)
and Québec (15 / million workers)
6. Prevalence studies in high-risk workplaces:
< 5 % for high-molecular-weight agents
5 to 10% for low-molecular-weight agents
7. Incidence studies of probable occupational asthma:
high-risk professions (Gautrin D et al. 1997 onwards)
in person-year: 7.9% (animal health), 4.2% (bakers),
2.5% (dental hygiene)
Frequency of asthma in the workplace
Occupational lung diseases
(Commission de la santé et sécurité du travail du Québec)
1988-2003
Year 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 Asthma
With a latency period
79 54 58 70 51 61 59 40 59 48 53 50 56 70 57 66
Without a latency period (Irritant-induced asthma)
8 8 7 5 10 2 3 2 0 4 2 5 5 7 1 2
TOTAL 87 62 65 75 61 63 62 42 59 52 55 55 61 77 58 68
Asbestos-induced lung diseases
77 57 53 76 66 61 71 70 113 84 84 99 116 108 132 158 Silicosis 40 31 42 45 25 38 27 18 26 24 38 21 29 19 28 32
Agents * Occupations
Flour and cereals BakersIsocyanates Spray-painters,
plastic industriesWooddusts CarpentersSeafood Seafood plants, restaurantsMetals WeldersResins, glues VariousAnimals Technicians, professionalsLatex and drugs Health professionals
* in bold : high-molecular-weight agents; others are low-molecular-weight agents.
Agents causant l’asthme professionnel avec période de latence
(Commission de la santé et sécurité du travail du Québec)
1988-2002
Année 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 Total
Agent
Isocyanates 17 17 18 23 16 25 8 7 11 7 8 9 12 11 10 199
Farine 10 9 9 16 5 9 11 8 13 9 6 12 11 5 8 141
Bois 12 6 6 5 3 8 3 1 6 6 7 2 7 8 5 85
Fruits de mer 7 2 2 7 0 2 9 2 2 5 4 6 3 8 6 65
Métaux 4 3 3 6 6 4 4 1 6 2 3 5 3 5 2 57
Résines, colles 0 1 4 4 3 4 5 5 4 1 3 6 2 5 1 48
Céréales 9 3 3 2 2 1 4 1 3 3 4 1 2 7 3 48
Animaux 3 2 3 3 4 2 5 1 3 0 6 3 0 3 1 39
Médicaments 6 5 3 2 1 1 1 0 1 2 0 0 0 2 0 24
* en noir: agents dits de faible poids moléculaire en bleu: agents dits de haut poids moléculaire
Agents causing occupational asthmawithout a latency period
Agents with irritant properties : vapors and aerosols,
more frequently than dusts.
Chlorine and ammoniac are the leading causes.
Relevance of skin reactivity to ubiquitous aeroallergens ?
Identification of atopy…but
1. ~ 50% of the general population is atopic;
2. Atopy is associated with occupational asthma due tohigh-molecular-weight agents only but the associationis weak
Relevance of smoking history ?
Occupatinal asthma is weakly associated with smokingfor a minority of agents.
Personal risk factors
Relevance of genes ?
Gautrin D et al. Am J Respir Crit Care Med 2001; 163:899-904
1. Definitions
2. Frequency and risk factors
3. Mechanisms
4. Identification and diagnosis
5. Medicolegal aspects
6. As a model for asthma
Asthma in the workplace
Type of occupational asthma Mechanisms
Occupational asthma with a latency period IgE (high-molecular-)
weight agents? (low-molecular-
weight agents)
Occupational asthmawithout a latency period(irritant-induced asthma) unknown
Asthma exacerbated at work unknown
1. Definitions
2. Frequency and risk factors
3. Mechanisms
4. Identification and diagnosis
5. Medicolegal aspects
6. As a model for asthma
Asthma in the workplace
occupational asthma is a disease that
can be cured : importance of early removal
(one year or less after onset of symptoms)
disease that affects young workers : sensitization
and symptoms mainly occur in the first
years after starting exposure
currently, 75% of workers
are left with permanent asthma (though mild)
Why should we consider intervention programs ?
1. Definitions
2. Frequency and risk factors
3. Mechanisms
4. Identification and diagnosis
5. Medicolegal aspects
6. As a model for asthma
Asthma in the workplace
In Canada
Asthma is accepted as an occupational lung disease
by all provincial medicolegal authorities.
Ideally, diagnosis should be confirmed by
objective means.
Assessment of permanent impairment/disabilitytwo years or more after cessation of exposure
Evaluation of 134 cases accepted by the Québec CSST, 1986-1988 *
On average…symptoms had started four years after starting exposure
8 % workers still unemployed two years after diagnosis(retraining into a new job in 22% workers)
total cost (readaptation + permanent disability) : ~ $ 50 000
satisfactory quality of life after two years.
* Dewitte JD et al. Eur Respir J 1994; 7:969
Malo JL, Ghezzo H. Am J Respir Crit Care Med 2004; 169:1304
Maghni K et al. Am J Respir Crit Care Med 2004; 169:367
Scale for assessing permanent impairment/disability
Based on airway caliber and hyperreponsiveness
as well as need for medication (inhaled steroids).
(other items: dose of inhaled steroids,
use of long-acting bronchodilator, sputum cells).
Endorsed by the American Medical Association.
Table 5. Quebec scaling system for assessment of disability for occupational asthma
Class level of level of need for % disabilitybronchial bronchial medication
obstruction responsiveness1 0 0 None 02A 0 1 None 52B 0 1 BDT prn 82C 0 1 BDT reg 102D 0 2 None 102E 0 2 BDT reg or prn 132F 0 3 BDT reg or prn 153A 1 1 BDT reg or prn 183B 1 2 BDT reg or prn 203C 1 3 BDT reg or prn 254A 2 1-2 BDT reg or prn 284B 2 3 BDT reg or prn 335A 3 1-2 BDT reg or prn 505B 3 3 BDT reg or prn 606 4 1-2-3 BDT reg or prn 100
with oral steroids and with or withoutinhaled steroids
to be added:inhaled steroid 3
oral steroid 10
Level of bronchial obstruction0: FEV 1 (% pred) and/or FEV 1/FVC (% pred) > 85% pred1: FEV 1 (% pred) and/or FEV 1/FVC (% pred) = 71- 85% pred 2: FEV 1 (% pred) and/or FEV 1/FVC (% pred) = 56-70% pred3:FEV 1 (% pred) and/or FEV 1/FVC (% pred) = 40-55% pred4: FEV 1 (% pred) and/or FEV 1/FVC (% pred) < 40% pred
Level of bronchial hyperresponsiveness0: PC 20 > 16 mg/ml1: PC 20 = 2-16 mg/ml2: PC 20 = 0.25 - 2 mg/ml3: PC 20 < 0.25 mg/ml
PC 20 assessed by the method of Cockcroft DW et al. Clin Allergy 1977
1. Definitions
2. Frequency and risk factors
3. Mechanisms
4. Identification and diagnosis
5. Medicolegal aspects
6. As a model for asthma
Asthma in the workplace
Natural history of occupational asthma and of asthma
onset ofexposure
sensitization occupationalasthma
end ofexposure
cure or persis-tence of asthma
Rhinoconjunctivitis;onset of airway inflammation
host markers:genetic;
atopy; level ofbronchial respon-
siveness;smoking,
psychosocial
agent:nature, concentration;duration of exposure;
other factors:viral infections,
pollutants, smoking,etc.
level ofbronchial
responsiveness
duration of exposure,duration of exposure after
onset of symptoms,asthma severity
at the time of diagnosis
anti-inflammatorytreatment;
compensation andpsychosocioeconomic
impact
Basic research,environmental and psychosocial
assessments
Clinical and epidemiological expertiseR & D projects
Evaluative examinationof surveillance
and compensation programs
1. Definitions distinction between occupational asthma and other conditions
2. Frequency and risk factorsasthma in the workplace : ~ 10% of adult-onset asthma
3. Mechanisms IgE-dependent or not identified
4. Identification and diagnosisintervention justified by possibility to cure and good prognosis
5. Medicolegal aspectsobjective diagnosis; scale to assess impairment/disability
6. As a model for human asthma
Asthma in the workplaceConclusion
Thanks to the team