Articles
Global economic burden of Chagas disease: a computational simulation model

https://doi.org/10.1016/S1473-3099(13)70002-1Get rights and content

Summary

Background

As Chagas disease continues to expand beyond tropical and subtropical zones, a growing need exists to better understand its resulting economic burden to help guide stakeholders such as policy makers, funders, and product developers. We developed a Markov simulation model to estimate the global and regional health and economic burden of Chagas disease from the societal perspective.

Methods

Our Markov model structure had a 1 year cycle length and consisted of five states: acute disease, indeterminate disease, cardiomyopathy with or without congestive heart failure, megaviscera, and death. Major model parameter inputs, including the annual probabilities of transitioning from one state to another, and present case estimates for Chagas disease came from various sources, including WHO and other epidemiological and disease-surveillance-based reports. We calculated annual and lifetime health-care costs and disability-adjusted life-years (DALYs) for individuals, countries, and regions. We used a discount rate of 3% to adjust all costs and DALYs to present-day values.

Findings

On average, an infected individual incurs US$474 in health-care costs and 0·51 DALYs annually. Over his or her lifetime, an infected individual accrues an average net present value of $3456 and 3·57 DALYs. Globally, the annual burden is $627·46 million in health-care costs and 806 170 DALYs. The global net present value of currently infected individuals is $24·73 billion in health-care costs and 29 385 250 DALYs. Conversion of this burden into costs results in annual per-person costs of $4660 and lifetime per-person costs of $27 684. Global costs are $7·19 billion per year and $188·80 billion per lifetime. More than 10% of these costs emanate from the USA and Canada, where Chagas disease has not been traditionally endemic. A substantial proportion of the burden emerges from lost productivity from cardiovascular disease-induced early mortality.

Interpretation

The economic burden of Chagas disease is similar to or exceeds those of other prominent diseases globally (eg, rotavirus $2·0 billion, cervical cancer $4·7 billion) even in the USA (Lyme disease $2·5 billion), where Chagas disease has not been traditionally endemic, suggesting an economic argument for more attention and efforts towards control of Chagas disease.

Funding

Bill & Melinda Gates Foundation, the National Institute of General Medical Sciences Models of Infectious Disease Agent Study.

Introduction

As Chagas disease continues to expand beyond its traditional range of tropical and subtropical zones, including to regions of the southern USA and Europe, a growing need exists to better understand its resulting economic burden, which in turn could drive much decision making. Policy makers in affected countries must work out where Chagas disease should be placed on their lists of public health, medical, and scientific priorities. Without a comprehensive estimate of the costs associated with Chagas disease, many questions remain. For example, how should policy makers prioritise prevention, education, treatment, and control for Chagas disease? How much should be invested in development of new diagnostic, prevention, and treatment interventions?

Much of the true economic burden of Chagas disease can remain hidden for years. Although up to 10 million people might be currently infected with Trypanosoma cruzi, the causative agent for Chagas disease, many infected individuals can remain asymptomatic for more than a decade. Many such individuals will be unaware that they are infected if not tested—a procedure that is not routine in most locations. However, once clinical problems such as cardiomyopathy, heart failure, and megaviscera (ie, enlargement of the oesophagus or colon) occur, the accompanying health care, disability, and death can be very costly. Moreover, these clinical symptoms are chronic and progressive, accruing costs over many years. There is increasing awareness of widespread Chagas disease in pregnancy with vertical transmission and congenital infection.1, 2 Although a few studies have offered estimates of the annual disability-adjusted life-year (DALY) burden of Chagas disease,3, 4 capturing this hidden future effect will require computational modelling to forecast the downstream effects of currently asymptomatic infections. We aimed to develop a simulation model to estimate the global health and economic burden of Chagas disease from the societal perspective (a commonly used economic perspective that includes health-care costs plus cost related to work absenteeism).5, 6

Section snippets

Model structure

We used TreeAge Pro (version 2009) and Microsoft Excel (version 2007) to develop a Markov computational simulation model, adapted from previously reported models.5, 6 Our Markov model structure had a 1 year cycle length (figure 1). Markov models are useful when a person has different time-dependent risks of undergoing different events or conditions over a long period, especially if the events or conditions can be easily separated into mutually exclusive states. A Markov model allows an

Results

For an individual with chronic disease, our simulations generated an annual health-care cost of $383 (range $207–636) in Latin America, $1762 ($942–2971) in Europe, and $2162 ($1158–3628) in the USA, Canada, and Australia. The global weighted average was $474 ($222–914). Annual DALYs per individual with chronic disease were 0·51 (range 0·38–0·60). The discounted lifetime health-care cost for an individual with T cruzi infection was $2600 (range $1966–3034) in Latin America, $14 948

Discussion

Our results show that on average an infected individual incurs $474 in health-care costs and 0·51 DALYs annually. Over the course of his or her lifetime, an infected individual accrues an average net present value of $3456 and 3·57 DALYs. Globally, the annual burden is $627·5 million in health-care costs and 806 170 DALYs. The global net present value of currently infected individuals is $24·73 billion in health-care costs and 29 385 250 DALYs. Conversion of the entire burden into US$ costs

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