Assessment of public health impact of work-related asthma

Abstract

Background: Asthma is among the most common chronic diseases in working-aged populations and occupational exposures are important causal agents. Our aims were to evaluate the best methods to assess occurrence, public health impact, and burden to society related to occupational or work-related asthma and to achieve comparable estimates for different populations.

Methods: We addressed three central questions: 1: What is the best method to assess the occurrence of occupational asthma? We evaluated: 1) assessment of the occurrence of occupational asthma per se, and 2) assessment of adult-onset asthma and the population attributable fractions due to specific occupational exposures. 2: What are the best methods to assess public health impact and burden to society related to occupational or work-related asthma? We evaluated methods based on assessment of excess burden of disease due to specific occupational exposures. 3: How to achieve comparable estimates for different populations? We evaluated comparability of estimates of occurrence and burden attributable to occupational asthma based on different methods.

Results: Assessment of the occurrence of occupational asthma per se can be used in countries with good coverage of the identification system for occupational asthma, i.e. countries with well-functioning occupational health services. Assessment based on adult-onset asthma and population attributable fractions due to specific occupational exposures is a good approach to estimate the occurrence of occupational asthma at the population level. For assessment of public health impact from work-related asthma we recommend assessing excess burden of disease due to specific occupational exposures, including excess incidence of asthma complemented by an assessment of disability from it. International comparability of estimates can be best achieved by methods based on population attributable fractions.

Conclusions: Public health impact assessment for occupational asthma is central in prevention and health policy planning and could be improved by purposeful development of methods for assessing health benefits from preventive actions. Registry-based methods are suitable for evaluating time-trends of occurrence at a given population but for international comparisons they face serious limitations. Assessment of excess burden of disease due to specific occupational exposure is a useful measure, when there is valid information on population exposure and attributable fractions.

Figure 1

Illustrates the relation between asthma and work. Work-related asthma includes occupational asthma and work-aggravated asthma. These may affect workability, but any asthma even if not related to work may influence the person's workability.

Figure 2

New cases of occupational asthma in Finland between 1983 and 2002 reported to the Finnish Register of Occupational Diseases [13]. The colour indicates the causal agent. The population of Finland in 2002 was 5 326 314, 20-64 yr population 2 839 686, employed population 2 380 863.

Figure 3

New cases of occupational asthma in West-Midlands, UK, between 1980 and 2002 reported to the SHIELD register [14,15]. The population of West-Midlands in 2001 was 5 267 308, 20-64 yr population 3 061 210, employed population 2 511 000.