Surveillance for isocyanate asthma: a model based cost effectiveness analysis

Abstract

Aims: Because logistical and financial obstacles impede using large prospective cohort studies, surveillance decisions in occupational settings must often be made without evidence of relative benefits and costs. Using the example of isocyanate induced asthma, the most commonly reported immune mediated occupational asthma, the authors developed a model based approach to evaluate the costs and benefits of surveillance from both an employer and a societal perspective. Methods: The authors used a mathematical simulation model of isocyanate asthma to compare annual surveillance to passive case finding. Outcome measures included symptom free days (SFD), quality adjusted life years (QALY), direct costs, productivity losses, and incremental cost effectiveness ratio (CER), measured from the employer and the societal perspectives. Input data were obtained from a variety of published sources. Results: For 100 000 exposed workers, surveillance resulted in 683 fewer cases of disability over 10 years. Surveillance conferred benefits at an incremental cost of $24,000/QALY (employer perspective; $13.33/SFD) and was cost saving from the societal perspective. Results were sensitive to assumptions about sensitisation rate, removal rates, and time to diagnosis, but not to assumptions about therapy costs and disability rates. Conclusions: Baseline results placed the CER for surveillance for isocyanate asthma within the acceptable range. Costs from the societal and employer perspective differed substantially with a more attractive CER from the societal perspective, suggesting opportunities for employer/societal cost sharing. The analysis demonstrates the value of a model based approach to evaluate the cost effectiveness of surveillance programmes for isocyanate asthma, and to inform shared decision making among clinicians, patients, employers, and society. Such a modeling approach may be applicable to surveillance programmes for other work related conditions.

Prevention of Occupational Asthma

“…A model to determine costs and benefits from medical surveillance for diisocyanates was reported by Wild et al [48]. Factors included the time to diagnosis with and without surveillance, disease progression with and without removal from ongoing exposure, chance of removal from exposure with and without diagnosis, and chance of recovery from asthma with and without removal from exposure.…”

Guidelines for the management of work-related asthma

“…10) Evaluations of surveillance programmes, consisting of medical surveillance (case finding), employers' feedback and exposure control measures, indicate that the incidence of workrelated asthma may decline following the introduction of a surveillance programme (**) [154][155][156][157][158].…”

“…11) Medical surveillance may reduce the occurrence of disability and socio-economic costs (*) [158].…”

Health economics of asthma: assessing the value of asthma interventions

“…Of the 14 policy evaluations six considered the economic effects of implementing an education program (22,24,25,28,30,32). Other studies evaluated management programs (23,26,29,33,35), guidelines (27), and surveillance (31,34). All 26 of the pharmaceutical comparisons were of controller medications.…”

“…Tables 1-4 contain detailed information on each of the economic evaluations organized by their intervention of interest: policy interventions (Table 1), monotherapy controller medications (Table 2), combination controller medications (Table 3), and add-on medications (Table 4). Of the 40 papers that we reviewed, 14 evaluated a policy intervention (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) and the other 26 were pharmaceutical comparisons . Of the 14 policy evaluations six considered the economic effects of implementing an education program (22,24,25,28,30,32).…”