A probabilistic approach for economic evaluation of occupational health and safety interventions: a case study of silica exposure reduction interventions in the construction sector

Abstract

Background: Construction workers are at a high risk of exposure to various types of hazardous substances such as crystalline silica. Though multiple studies indicate the evidence regarding the effectiveness of different silica exposure reduction interventions in the construction sector, the decisions for selecting a specific silica exposure reduction intervention are best informed by an economic evaluation. Economic evaluation of interventions is subjected to uncertainties in practice, mostly due to the lack of precise data on important variables. In this study, we aim to identify the most cost-beneficial silica exposure reduction intervention for the construction sector under uncertain situations.

Methods: We apply a probabilistic modeling approach that covers a large number of variables relevant to the cost of lung cancer, as well as the costs of silica exposure reduction interventions. To estimate the societal lifetime cost of lung cancer, we use an incidence cost approach. To estimate the net benefit of each intervention, we compare the expected cost of lung cancer cases averted, with expected cost of implementation of the intervention in one calendar year. Sensitivity analysis is used to quantify how different variables affect interventions net benefit.

Results: A positive net benefit is expected for all considered interventions. The highest number of lung cancer cases are averted by combined use of wet method, local exhaust ventilation and personal protective equipment, about 107 cases, with expected net benefit of $45.9 million. Results also suggest that the level of exposure is an important determinant for the selection of the most cost-beneficial intervention.

Conclusions: This study provides important insights for decision makers about silica exposure reduction interventions in the construction sector. It also provides an overview of the potential advantages of using probabilistic modeling approach to undertake economic evaluations, particularly when researchers are confronted with a large number of uncertain variables.

Keywords: Bayesian networks; Cost-benefit analysis; Lung cancer; Net benefit; Probabilistic modeling approach; Uncertainty.

Fig. 1

Steps of a Probabilistic Modeling Approach for Economic Evaluation of Silica Exposure Reduction Interventions

Fig. 2

A Simplified Representation of Economic Evaluation Model of Silica Exposure Reduction Interventions, Using Bayesian Network. Note. Ellipses represent random variables, rectangles represent silica exposure reduction intervention options as decision variables, and hexagons represent costs as values or utility nodes, Interventions: wet method (WM), local exhaust ventilation (LEV), personal protective equipment (PPE), and combinates of the following: WM-LEV-PPE, WM-LEV, WM-PPE, LEV-PPE, primary silica exposure: level of exposure to silica dust before an intervention, effectiveness: reduction ability of silica exposure interventions, coverage: percentage of silica-exposed workers that a specific intervention is applicable to, unit cost: cost of implementation of an intervention, direct costs: sum of healthcare, informal care, and out-of-pocket costs of lung cancer cases. Indirect cost: sum of output/productivity losses and home production losses of lung cancer cases, intangible cost: monetary value of health-related quality of the life losses of lung cancer case