Www.asthma-workplace.com. Program: CIHR Centers for Research Development: Understanding/Addressing Physico-Social Environment, Financial partners: IRSST.

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