A dynamic population-based model for the development of work-related respiratory health effects among bakery workers

Abstract

Objectives:This paper presents a dynamic population-based model for the development of sensitisation and respiratory symptoms in bakery workers. The model simulates a population of individual workers longitudinally and tracks the development of work-related sensitisation and respiratory symptoms in each worker.Methods:The model has three components: a multi-stage disease model describing the development of sensitisation and respiratory symptoms in each worker over time; an exposure model describing occupational exposure to flour dust and allergens; and a basic population model describing the length of a worker’s career in the bakery sector and the influx of new workers. Each worker’s disease state is modelled independently using a discrete time Markov Chain, updated yearly using each individual’s simulated exposure. A Bayesian analysis of data from a recent epidemiological study provided estimates of the yearly transition probabilities between disease states.Results:For non-atopic/non-sensitised workers the estimated probabilities of developing moderate (upper respiratory) symptoms and progression to severe (lower respiratory) symptoms are 0.4% (95% CI 0.3 to 0.5%) and 1.1% (95% CI 0.6 to 1.9%) per mg/m3/year of flour dust, respectively, and approximately twice these for atopic workers. The model predicts that 36% (95% CI 26 to 46%) of workers with severe symptoms are sensitised to wheat and 22% (95% CI 12 to 37%) to α-amylase. The predicted mean latency period for respiratory symptoms was 10.3 years (95% CI 8.3 to 12.3).Conclusions:While the model provides a valuable population-level representation of the mechanisms contributing to respiratory diseases in bakers, it was primarily developed for use in quantitative health impact assessment. Future research will use the model to evaluate a range of workplace interventions, including achievable reductions in exposure and health surveillance. The general methodology is applicable to other diseases such as chronic obstructive pulmonary disease, silicosis and musculoskeletal disorders and could be particularly valuable for forecasting changes in long latency diseases.

Cost-benefit analysis in occupational health: a comparison of intervention scenarios for occupational asthma and rhinitis among bakery workers

“…In addition the input parameters to which the model is most sensitive, especially the number of disease years for asthma and the costs of a lost work day, are underpinned by high quality epidemiological data and specific income data from labour agreements. Regarding the input from the health impact model, a detailed sensitivity and uncertainty analysis can be found in the paper by Warren et al 13. For some of the input variables for which information was scarce, such as the cost information for rhinitis, the sensitivity of the model is limited.…”

“…A recently developed dynamic population based model for respiratory health effects in bakery workers was used to simulate the health impact of the intervention scenarios 13. The model simulates the development of disease in a fixed worker population of 10 000 workers, the approximate size of the Dutch bakery population at risk, longitudinally over a period of 20 years.…”

“…One of the main aims of the methodology is to facilitate the evaluation of cost-benefit ratios for different stakeholders (employers, employees and society (tax-payers)). The presented conceptual model for cost-benefit analysis can be seen as an extension of the quantitative HIA method described by Warren et al 13. The developed methodology is applied to a case study on work related respiratory diseases among Dutch bakery workers.…”

What is the best strategy to reduce the burden of occupational asthma and allergy in bakers?

“…The dynamic model simulates a population of workers which is followed over time and tracks the development of work related symptoms in each individual worker related to their occupational exposure 17. Model parameters came from a series of recently published surveys.…”

“…To perform quantitative health impact assessment related to occupational exposure and respiratory diseases in bakery workers, a dynamic population based model was recently developed 17. This model describes the onset and progression of work-related sensitisation and respiratory symptoms as well as work disability, in relation to occupational exposure over time.…”