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    Conceptual framework of the economics of trachoma.

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    Number of cases of pre-visual impairment trichiasis per case of trachomatous blindness at which the burden from pre-visual impairment will equal the burden from trachomatous low vision and blindness for varying disability adjusted life year weights. Based on data in Frick and others.32

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    Total potential productivity loss in billions ($5.3 billion 2003 U.S. dollars). Based on data in Frick and others.32

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    Regional prevalence of trachomatous blindness by economic status sized by population. SSA = sub-Saharan Africa; CHI = China; OAI = Other Asia/Islands; IND = India; MEC = Middle Eastern Crescent.

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    Division of dollars of lifetime cost of illness avoided by trichiasis surgery (1998 U.S. $89).5

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    Costs of antibiotics and trichiasis surgery yielding zero net benefit.

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    Realized potential gain and taxation combination that led to zero net cost for the government and donor from 2004 to 2020 with varying prices of azithromycin.

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GLOBAL BURDEN OF TRACHOMA AND ECONOMICS OF THE DISEASE

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  • 1 Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Health Services Research and Development Center, Department of Economics, Department of Ophthalmology, and Department of International Health, Johns Hopkins University, Baltimore, Maryland

Interest in the economics of trachoma is high because of the refinement of a strategy to control trachomatous blindness, an ongoing global effort to eliminate incident blindness from trachoma by 2020, and an azithromycin donation program that is a component of trachoma control programs in several countries. This report comments on the economic distribution of blindness from trachoma and adds insight to published data on the burden of trachoma and the comparative costs and effects of trachoma control. Results suggest that 1) trichiasis without visual impairment may result in an economic burden comparable to trachomatous low vision and blindness so that 2) the monetary burden of trachoma may be 50% higher than conservative, published figures; 3) within some regions more productive economies are associated with less national blindness from trachoma; and 4) the ability to achieve a positive net benefit of trachoma control depends importantly on the cost per dose of antibiotic.

INTRODUCTION

Health economics has the potential to inform policy-making regarding trachoma control and other disease control programs. Economics provides a paradigm for motivating health behaviors, describing the distribution of the effects of a disease and its sequelae, and evaluating the relative costs and benefits of disease control programs. This is not to say that economics should be the only reason for policy and the only paradigm for describing the distribution of the disease and its effects; rather that economics has the capacity to provide information that can be used in the policy making process alongside political, moral, ethical, and other considerations. We have 1) developed a conceptual framework to motivate the consideration of the economics of trachoma; 2) summarized several recent frameworks/reviews of economic evaluations; 3) developed a framework for considering economic equity and trachoma and summarized evidence regarding the distribution of the effects of trachoma; and 4) performed additional analyses of data published in recent articles on the burden of trachoma and the cost-effectiveness of trachomatous blindness control programs. We have demonstrated that the true economic burden of trachoma may be higher than recently published conservative figures as a result of the burden of trichiasis prior to visual impairment. Furthermore, this, in combination with the cost per dose of antibiotic, has an important effect on whether the net benefit of a trachoma blindness control program will be positive in the long run.

MATERIALS AND METHODS

Conceptual framework.

Economics is the study of individual and societal allocation of scarce resources.1 Economics can involve studies of 1) individuals’ demand for goods and services,2 2) individuals’ health behaviors that are affected by the availability of scarce resources and the quantity of scarce resources required to adopt the behaviors,3 3) the production of goods and services,4 and 4) the comparison of the costs and value of outcomes of health or other programs.5 Economic measures can also be used in the description of the distribution of health conditions that are the result of the choices that have been made.6

The conceptual framework that will be used as the basis for the remainder of this report is shown in Figure 1. It shows a combination of factors that influence individual decisions, points at which the government can intervene to change individual decisions, the process of changes in health and the resulting burden from health conditions, and the outcomes for economic description and economic evaluation. The outcomes are in the boxes with double outlines.

The first two boxes in the leftmost column represent factors that are assumed to affect individual behavior in all economic analyses: resources, preferences, and information.1 Resources are a combination of the individual’s own income and wealth and resources that might be available from family members or friends. Resources also include the time available to participate in positive health behaviors and obtain treatments.7 Preferences are unique to the individual and are a function of individuals’ beliefs, personal feelings about the relative valuation of different goods and services, and information that is available.

Individuals’ health behaviors are also a function of the health conditions that affect them (third box in the leftmost column).8 Finally, the price and availability of health services also influence health care use.9,10 An individual making a decision about health behaviors and medical treatments must consider how using resources to adopt specific behaviors or obtain treatments affects the quantity of resources available to obtain other goods and services. The last two boxes in the leftmost column indicate the price and access considerations.

Given the five factors listed in the boxes in the leftmost column, individuals make choices (indicated by dashed lines) regarding health behaviors and medical treatment. The health behaviors and medical treatments then affect additional health conditions and sequelae related to the original health conditions (also designated by dashed lines). This combination of conditions and their sequelae results in a burden or changes the burden.

The bold lines leading to the boxes with double outlines indicate the measurement of results that are reported in economic studies. Results related to individual choices include the costs of the behaviors or treatments, the economic valuation of the burden, and the description of the economic distribution of the use of medical treatment. Costs and burden can be measured at the societal or individual level. Individual costs are key to individual behavior and are a necessary component of a societal cost-outcome analysis.11 The burden can be measured in terms of impairments, disability, handicap, quality of life, or direct economic outcomes such as lost productivity or the value of time. Methods have been developed to calculate disability, handicap, and quality adjusted life years. The appropriate valuation of time is a topic of ongoing debate and may be construed as the value of time for the individual, the value of lost macroeconomic production in general, or the value of lost macroeconomic production under conditions of full employment, team production, or production where missing deadlines matters.12–15 While the last type of valuation has not been the focus of analyses in developing economies, missing deadlines would seem important in a subsistence agricultural economy. Monetary and time costs, the demand for services, and individual valuation of services have all played a role in previous economic evaluations.

Thin solid lines are drawn from the government/donor box the potential points of intervention. Interventions can be designed to 1) provide information to help individuals better understand a disease, its effects, and its treatment, 2) subsidize the price of medical treatment, or 3) make providers more available. Alternatively, the government or donor could provide the treatment directly. Any intervention would lead to costs that can be reported as an outcome and are a component of a cost-outcome evaluation.

Cost-outcome evaluations (also in a bold outlined box) use data on the costs and effects to assess the cost-effectiveness or net-benefit of an intervention.11,16

For trachoma specifically, the SAFE (surgery for trichiasis, antibiotics to treat active disease, face washing, and environmental improvements to limit transmission) strategy aimed at limiting trachomatous blindness affects several of the items in Figure 1.17,18 Programs to make surgery more accessible focus on training surgeons, providing surgeons at local rather than regional levels, or decreasing the price.5,19 Antibiotic interventions make the antibiotics more available.20,21 The azithromycin donation program in particular has not required recipients to pay anything for the antibiotic, thus also reducing the price. Encouraging face washing changes the information that is available.22 Efforts to advocate for clean water change the availability of resources to achieve face washing and improve hygiene generally.23 Finally, environmental change, such as trying to decrease the prevalence of flies, is essentially a health behavior, although not one that can often be affected by individuals.24 The remainder of the Materials and Methods, Results, and Discussion sections will discuss the boxes associated with the diverse set of economic outcomes for trachoma control programs: the economic distribution of trachoma and its control, the burden of the sequelae of trachoma, costs of trachoma control, and the cost-effectiveness of trachoma control.

Review of recent summaries.

Several recent publications have provided reviews or frameworks for economic analysis. The first proposed a framework for the analysis of the antibiotic component of the SAFE strategy and suggested how the framework might be extended to include other components of the SAFE strategy.25 Specific data elements that could be used to describe the quantities and prices of resources required to implement the antibiotic component of the SAFE strategy were discussed. This framework focused only on cost and cost-outcome studies.

A second framework for building models for cost-effectiveness studies of trachoma control programs focused on the overall SAFE strategy over the long-term rather than the antibiotic component over a fairly short-term.26 This framework referred the reader to epidemiologic and operations research data useful for building a model of long-term trachomatous blindness control programs and identified additional data that would be needed to build a more complete model. Data included risk factors for trachoma and its sequelae. At the time this framework was published, there were fewer economic analyses of trachoma control than there are today and there were (and still are) few long-term analyses of the epidemiology related to or cost-effectiveness of trachoma control programs.27

A recent review of trachoma control program cost-outcome studies provided more information than the two frameworks because of the increase in the number of economic analyses during the past five years.28 The review concluded that even with five studies the cost-effectiveness of the SAFE strategy as a whole was unclear.5,27,29–31 The difficulty with drawing conclusions about antibiotic programs (other than the tetracycline that was administered during the 30 years of observation in Burma) is that the effects of a small number of doses of antibiotics on the long-term changes in blindness are difficult to model.27 Trichiasis surgery appears to be highly cost-effective and will receive further consideration in this report.5,31 The program in Burma (that was not coordinated as a SAFE strategy program because the SAFE strategy was only defined within the past ten years) also appeared to be relatively cost-effective.27

One topic that has not been covered previously and will not be covered here is studies of the private supply of services and personnel time. Another topic not covered in the economic reviews was the economic distribution of the burden of trachoma and its control costs. The latter topic will be the first topic explored as a new item in this report.

Since these recent reviews of the literature, there has been limited new information on the economics of trachoma and trachoma control: an analysis of the global burden of trachoma and an analysis of adults’ willingness to pay for a second azithromycin treatment of their children.32,33 The results below will add insight and reinterpretation to the burden estimates, and the willingness to pay study will be mentioned in the Discussion.

Economic distribution analysis-equity.

One use of economic data is describing the distribution of a disease and its sequelae with a focus on differences in resources available and a view toward economic equity. A framework for considering equity begins with the September 1978 “Declaration of Alma-Ata” that was signed by participants of the International Conference on Primary Health Care, urging the “world community to protect and promote the health of all people.” The declaration focused on gross inequalities in health status around the world and suggested that these were “politically, socially and economically unacceptable.”34 In 1979, the member states of the United Nations endorsed the Alma-Ata declaration and adopted a global target of “Health for All by 2000.” This initiative called for the “attainment by all people of the world by 2000 a level of health that will permit them to lead a socially and economically productive life.”35 By referring to all people, the Health for All target brought the concept of equality in health to a position of political prominence.

Defining equality in health, however, has proven to be complex. Equality in health may be translated, among other things, as geographic equality in financial resource allocation, equality in the distribution of health facilities, sex equality in health outcomes, or equality in the prevalence of disease. Some authors have specified the definition of equality to suggest that it is equality in the opportunity for health that best reflects the social justice aims behind Health for All.36,37

Promoting health equality has been frequently translated into efforts to reduce the “gaps” between the advantaged and the disadvantaged, primarily by improving the status of the least well-off. Evidence suggests that individuals prefer societies with more equal distributions of health.38 Of course, efforts to increase life expectancies for the disadvantaged may result in less resources devoted to increasing the life expectancies for the advantaged. One philosopher suggested: “what makes us care about various inequalities is not the inequality but the concern identified by the underlying principle…our concern for the hungry, the needy, the suffering, and not our concern for equality, makes us give them priority.”39,40

The notion of health equity recognizes that it is the disproportionate ill-health among the disadvantaged that evokes the call for health equality. Inequities in health are often referred to as inequalities that are unfair and avoidable. More specifically, some authors have suggested that inequities refer to the inequalities that are attributable to factors beyond the control of individuals.41 Perhaps the most comprehensive definition is “the absence of potentially remediable, systematic differences in one or more aspects of health across socially, economically, demographically, or geographically defined population groups or subgroups.”42

Where individuals may not perceive or be able to correct their own “worse-off” status, societal obligation to the individual is heightened.43 Societal responsibility with respect to trachoma can be operationalized in the opportunities for intervention discussed with respect to Figure 1. The role of public health systems in redressing health inequities is evident as public health systems have a mandate to protect and promote the health of the entire population.

Defining those who are “most in need” has sparked considerable debate in the literature and among international organizations. Based on a model of health equality rather than health equity, some authors have suggested that increased priority should be given to individuals in the worst health states, i.e., health status should be the only measure for determining inequalities.44 Others have suggested identification of those most in need based exclusively on socioeconomic or even purely economic factors, e.g., those living on less than US $1 per day.45,46 One of the complexities in identifying those most in need is that they may be the most difficult to reach because they often are not accessing formal health care, not enrolled in schools, and not used in the formal sector.

Some consensus seems to be building in the literature that a more inclusive definition of those “most in need” is relevant. The United Nations Development Program monitors the development status of countries in terms of a human development index that combines health status, wealth and educational achievement data.47 Poverty can be considered as multi-dimensional in terms of a lack of material well-being (e.g., land, housing, food), absence of infrastructure (e.g., limited access to roads, clean water, health services), and a lack of power (e.g., decision-making capabilities, access to information).48 Adopting this definition of poverty enables consideration of the determinants of the poverty cycle rather than only a quantification of the current economic situation.

A literature review was conducted using Medline to search for articles on the distribution of trachoma using search terms such as trachoma and poverty and relying on experts in the field who were aware of the literature on trachoma and poverty or other distributional parameters of interest.

Burden analysis.

The global burden of trachoma was recently described using a combination of techniques including the global burden of disease disability adjusted life years measure and a dollar figure. We add new insight to the previously published data.

First, the analysis of the global burden of trachoma did not include a weight for cases of pre-visual impairment trichiasis.32 Other recent work has demonstrated that at least among women in Tanzania, women with pre-visual acuity loss trichiasis were as limited in their functional activities because of problems with their eyes as individuals who had visual acuity loss. Women with both trichiasis and visual acuity loss were significantly more limited than women with visual acuity loss who did not have trichiasis. The data for men trended in the direction of the data for women but only for men with visual acuity loss.49

If we extrapolate from the findings for women in Tanzania to the remainder of the global population with trichiasis as a result of trachoma, this finding suggests that any estimate of the burden of trachoma that does not account for pre-visual impairment trichiasis cases may underestimate the total burden of trachoma.32,50 While the findings from Tanzania suggest a similar degree of functional limitations, we do not simply assume that trichiasis without visual acuity loss should have the same weight as low vision in calculating disability adjusted life years or economic productivity loss. Additionally, the epidemiologic data documenting the number of trichiasis cases worldwide are not as good as the epidemiologic data on the number of cases of trachomatous blindness or low vision. For presentation, we calculated and plotted combinations of the number of pre-visual impairment trichiasis cases per case of blindness from trachoma and the disability weight for trichiasis that would lead to a doubling of the total burden due to trachoma. The highest disability weight that was allowed was the weight that was used for low vision (0.245).51

A second reinterpretation of the burden data transformed the reported data in three ways. First, the dollar amount was inflated to year 2003 United States dollars.52 Second, the productivity loss assigned for blind individuals was adjusted to indicate a complete loss of productivity rather than the 60% that was assumed in the published dollar estimate.51 Other analyses of the cost of blindness in general have assumed 90–100% productivity loss.53,54 Also, an informal care cost was added based on the assumption that 10% of a sighted adult’s time is needed to care for a blind adult.54

One further reinterpretation of the burden data combined the topics of burden and economic distribution. In World Development Report regions in which at least some countries were classified as having known or suspected blinding trachoma, not all were included on the lists of countries with known or suspected blinding trachoma. One way in which the international distribution of the burden of trachomatous blindness can be assessed is to plot the value of economic productivity against the prevalence of blindness from trachoma. The data points are averages within groups of countries from the regions including China, India, Middle Eastern Crescent, Other Asia/Islands, and Sub-Saharan Africa. Countries are grouped by whether they are on the list of countries with known or suspected blinding trachoma.55 China and India are special cases as each is the only country in its World Development Report region. The data points are weighted by the populations in the countries. The economic productivity measure is based on the weighted average annual value added per agricultural worker, the measure of economic productivity that was used to estimate the burden originally.56

Cost-benefit analysis.

Economic theory suggests that profit maximizing firms should produce (or produce more if some production is already going on) if the variable costs are less than the price of the good in the market.1 Similarly in a cost-benefit analysis, if the average willingness to pay is greater than the variable costs, the government could increase welfare by providing more of the service. Data from a previous report on a program to increase the availability of trichiasis surgery in The Gambia were reframed to show the relationship between the average willingness to pay, the variable costs, and the total productivity gain that was projected to provide further insight on the likely net benefit of a trichiasis surgery program.5

No study to date analyzes the net benefit of the entire SAFE strategy. As mentioned earlier, one study analyzed a national program in Burma.27 Projections of combinations of costs and benefits that yield zero net benefit at a discount rate of 3% were made in two ways.11 This type of threshold analysis allows us to determine whether conditions are likely to be favorable or unfavorable for a positive net benefit from the SAFE strategy. To make these projections, several assumptions were needed. The first assumption was that the entire cost of blindness from trachoma can be avoided starting in 2004. We expressed the annual burden that could be avoided in year 2003 US$ at the level of burden in the recently published article ($3.5 billion). This will bias the results for a positive net benefit since the total burden should decrease during as the prevalence of blindness from trachoma decreases with continuing prevention efforts. In contrast, we will use the published figures suggesting that 146 million people are at risk of trachoma and assume that all will need to be treated each year between 2004 and 2020.57 The latter part of this assumption biases against a positive net benefit. Based on these assumptions and the assumed need for five million trichiasis surgeries, the first analysis started with the 2003 cost of trichiasis surgery in The Gambia of $6.93 and calculated the cost of a dose of antibiotic administered to 146 million people each year for 17 years that would lead to a zero net benefit.5,52,57 The cost of surgery was varied up to 20 times its original level.

The second projection examined only the cost of antibiotics. The cost ranged from the maximum cost at which the maximum number of doses needed can be given to achieve a zero net benefit to the cost of an Indian produced azithromycin dose of $1.58.58 At each price, the graph plots the relationship between two parameters. The graph primarily indicates what proportion of the projected lost productivity would actually need to be made up each year to yield a zero net benefit. However, the graph also showed, in a governmental perspective cost-benefit analysis, the combinations of productivity gains and taxes that would be necessary to offset the costs. The societal analysis is essentially the governmental analysis with no taxes. The cost of per dose of any antibiotic (including transportation and administration) is relevant for a government perspective for countries in which the azithromycin donation program is not active. In a country with a drug donation program, the cost from a governmental perspective includes primarily transportation and administration, but the societal perspective (which is recommended from an economic decision making perspective) would still include the opportunity costs of using the drug.11

RESULTS

Economic distribution analysis.

There is considerable evidence in the literature to suggest the existence of important inequalities in the burden of trachoma. Trachoma disproportionately affects poor countries, with 12 of the 16 World Health Organization (WHO)-designated priority countries being low-income countries. Within low and middle-income countries, there is evidence suggesting that the geographic distribution of trachoma frequently reflects a higher burden in relatively rural, poor regions. Trachoma seems to cluster around disadvantaged communities and around relatively poor households within communities. In particular, increased prevalence of trachoma has been linked with relatively poor household wealth, low education level of the head-of-household, poor hygiene practices, and crowding.59–62

In endemic countries, the incidence of inflammatory trachoma is consistently highest among children less than five years of age. Women develop blindness from trachoma at a rate 2–3 times that of men.63 Women’s proximity to the children exposes them to repeated infection more than men, and this may lead to the higher incidence of blindness.64 Women have almost four times the risk of trichiasis than men, suggesting a considerable excess of trachoma-related disability occurring among women. Compounding the risk for women, the social consequences of visual impairment and blindness may disproportionately impoverish women’s power and role in families and societies.

Numerous studies have substantiated the importance of facial cleanliness among children to the control of trachoma.61,65,66 While several studies have found a correlation between the availability of water and reduced trachoma infection, most of the recent literature suggests that it is the household use of available water for personal hygiene that is most important.66 Studies have shown a correlation between the allocation of water for person hygiene and several socioeconomic variables such as education level, knowledge of the benefits of personal hygiene, and household wealth.

Environmental factors also play an important role in the incidence of trachoma, particularly as they relate to controlling fly populations. Increased prevalence of trachoma has been shown to be correlated with cattle ownership, living in close proximity to cattle, and high fly density in and around the household.67,68 Paradoxically, cattle ownership in many countries is correlated with a relatively high level of wealth. As one mechanism to reduce fly concentration near living quarters, the use of adequate latrines has been shown effective in reducing the incidence of trachoma.69 Several studies suggest that populations affected by trachoma have limited awareness of the importance of adequate personal hygiene and the cause and potential treatment options for trachoma. From an equity perspective, an uninformed or misinformed choice that is detrimental to health is unfair and contributes to health inequity. The literature has suggested that the population in highly endemic areas has limited knowledge of the finding that repeated childhood trachoma infection is linked to blindness in adulthood.70 A study in Nigeria noted that 90% of individuals with trichiasis did not seek care with many citing the cost of care-seeking as prohibitive.71

Burden analysis.

The combinations of number of cases of pre-visual impairment trichiasis per case of trachomatous blindness and disability weight of pre-visual impairment trichiasis that would lead to pre-visual impairment trichiasis having the same burden as trachomatous low vision and blindness are shown in Figure 2. If trichiasis without visual impairment had the same disability weight as low vision, only four cases of pre-visual impairment trichiasis per case of trachomatous blindness would be needed for pre-visual impairment trichiasis to have the same annual burden as trachomatous low vision and blindness. If the disability weight associated with pre-visual impairment trichiasis were lower, the number of cases to make the relationship hold would increase non-linearly. More than 18 cases of pre-visual impairment trichiasis per case of trachomatous blindness would be needed if the disability weight were only 0.05. All combinations above and to the right of the line in the graph on Figure 2 suggest a greater burden from pre-visual impairment trichiasis than from trachomatous low vision and blindness.

The breakdown of the total maximum dollar burden associated with trachomatous low vision and blindness is shown in Figure 3. The section indicating $2.2 billion dollars is the inflation adjusted figure for trachomatous blindness alone. When combined with the $1.3 billion section, this represents the $3.5 billion total in US$ in the year 2003 that is the inflation-adjusted amount that was published as $2.9 billion in 1995 US$. The other two sections represent the $1.5 billion increase in the cost due to trachomatous blindness if all productivity is assumed to be lost and the $370 million additional loss from needing a sighted adult to care for a blind adult. The total addition of nearly $1.9 billion dollars is 35% of the total, which is now more than 150% of what it would otherwise be.

Figure 4 helps to demonstrate the difficulty of definitively concluding that blindness from trachoma primarily affects the least well off in international comparisons when countries public health and economic systems are affected by so many other health conditions (e.g., human immunodeficiency virus/ acquired immunodeficiency syndrome); however, even in international comparisons, it is clear that countries with known or suspected blinding trachoma are poorer and include none of the countries in established market economies with the exception of Australia. The relationship between the annual average value added per agricultural worker and the prevalence of trachomatous blindness is shown in Figure 4. The anticipated relationship is found when comparing the countries from the Middle Eastern Crescent and Other Asia/ Islands with and without blindness from trachoma. The countries with a higher economic productivity on average have a lower (zero) prevalence. China and India have both a relatively low prevalence of blindness from trachoma and a relatively low level of economic productivity. Sub-Saharan Africa is a special case. The countries in sub-Saharan Africa with blindness from trachoma have a relatively low level of economic productivity in comparison with the Middle Eastern Crescent or Other Asia/Islands countries that do not have blindness from trachoma. However, the countries in sub-Saharan Africa without blindness from trachoma are also very poor. Thus, while it is clear that the countries with trachomatous blindness are very poor, on average, support for the notion that the poorest of the poor countries are where the burden is greatest will only come from data that is at a more detailed level. Using an alternative measure of economic productivity, the gross domestic product per capita, yields a similar graph. It is notable that 39 of the 60 countries on the list of countries with known or suspected blinding trachoma had annual average value added per agricultural worker figures of less than $1,000 in 1998. Among all countries, there are 89 countries with annual average value added per agricultural worker less than $1,000 and 120 above that level, a much different ratio than countries with known or suspected blinding trachoma.

Cost-benefit analysis.

The relationship between the total lifetime productivity gain estimated at $89 for individuals who obtained trichiasis surgery in The Gambia and the total costs that are divided into fixed and variable costs is shown in Figure 5. The variable costs are subdivided into the average willingness to pay and the excess variable costs. If the average willingness to pay were the correct value for an economic evaluation, it would not even cover the variable costs. In contrast, the average lifetime benefits exceed the average total cost by $83.

The range of prices of the antibiotic that when combined with the price of the surgery yield zero net benefit is shown in Figure 6. Interestingly, varying the cost of surgery from the estimated cost in The Gambia to 20 times that level leads to very little difference in the cost of a dose of antibiotic at which the net benefit of a comprehensive blindness from trachoma control strategy is zero. The cost per dose of antibiotic administered that would allow for a positive net benefit is over US$25 at any reasonable price of surgery.

Figure 7 shows that at a low cost per dose of antibiotic, only 6% of the projected gain needs to occur on average each year between now and 2020 for the total benefit to be as high as the total cost. In this case, it may be possible to achieve a positive net benefit by 2020. However, at a cost of even $10 per dose, including transportation, storage, and distribution, 38% of the total projected lost productivity must be attained to achieve a positive net benefit for society. Alternatively, if the government were bearing the cost the government could break even if 100% of the gain were achieved and it were taxed at 38%. From a societal perspective, it would require only 38% of the gain to occur.

DISCUSSION

We have provided a review of elements of the economics of trachoma that appear in Figure 1 and that have not been reviewed in the past three years and added insight to recent publications on economics of trachoma. In expanding on past findings, we have demonstrated that the burden of the sequelae of trachoma could be much larger than previously suggested as a result of pre-visual impairment trichiasis cases and the individual and informal care-related productivity losses. When performing an economic evaluation of the SAFE strategy, the method of valuing the effects of successful trichiasis surgery was shown to be important, and the cost of antibiotics is likely to dominate the determination of whether the SAFE strategy has a positive net benefit. A review of the literature following the equity framework suggested that individual level analyses tend to support the notion that trachoma and its sequelae affect those who are least well off, with the exception of cattle ownership. Comparisons of countries that are and are not on the list of nations with known or suspected blinding trachoma also support this notion. However, comparisons among regions or of countries within regions do not support this as strongly. Still, the conclusion that trachoma affects a very poor population can be drawn safely.

The consideration of the costs and benefits of trachoma control is not new. While there has still not been successful development of a vaccination against Chlamydia trachomatis, as far back as 1972 the costs of developing such a vaccination were considered in light of the possibility of eliminating trachomatous blindness, and there is a new study looking at how environmental and personal factors affect the price of a vaccination at which a vaccination program could possibly achieve a positive net benefit.72,73 The importance of considering the economics of trachoma control continues to be important today because there are other public health needs competing with an infectious disease that leads to blindness in adulthood.

Policy analysts need to continue to develop methods of valuing long-term effects of the SAFE strategy. Part of this is an epidemiologic modeling exercise extending previous work.74 However, part is developing methods of placing dollar values on long-term benefits in societies in which borrowing against future earnings is difficult. This concept has been explored theoretically, but further empirical work is necessary.75 Both inferences based on observed behavior and direct questioning in contingent market valuations have led to seemingly low estimates of the value of components of the SAFE strategy in trachoma-endemic countries.5,33

Additionally, we have shown the fraction of the lost productivity that needs to be obtained from varying perspectives at varying prices per dose of the antibiotic to achieve a zero net benefit. Interestingly, if one were to take a very long-term view and model the program’s costs with no effects until 2020 and then the effects for the remainder of 100 years (as the WHO Evidence for Health Policy Group does), the benefit is actually larger, even though the discounting of the first year of benefit is considerably larger.76 In this case, even a smaller amount of the benefit would need to be gained. In addition, it is unlikely that all 146 million individuals at risk of trachoma would need to be given the antibiotic each year to eliminate trachoma as a cause of incident blindness (as was assumed in our cost analysis). Finally, all of the analyses in this report focused on changes in productivity only and not on changes in quality of life or the potential for an increased risk of mortality for blind individuals.77–80

While economic analyses to date and in the present work have provided a foundation for making more informed decisions about trachoma control resource allocation than was available 10 years ago, additional work is required. At present, work is funded by the International Trachoma Initiative for cost and cost-outcome studies of trichiasis surgery in Tanzania, Nepal, and Vietnam; for a willingness to pay for trichiasis surgery study in Tanzania; and for cost-effectiveness analyses of the antibiotic component of the SAFE strategy in Tanzania. Most importantly, given evidence that individuals are likely to express a low value of treatment, a more complete understanding of the effects of blindness on societal productivity and the costs of the full SAFE strategy are needed. One other policy option that has been discussed is changes in the market for pharmaceuticals so that azithromycin would be available at a lower cost in developing countries, although this possibility was not addressed in the present work.58

To contribute to better vision health outcomes, potentially improved economic development, and increased health equity through a holistic approach that includes pharmaceutical products, medical treatment, and hygienic and environmental change, the economics of trachoma will need to continue to be a focus of ongoing research. This may be achieved by including economic outcome measures directly in program monitoring. Economic findings will also need to be integrated into the policy process and development of strategic plans as one of many important considerations. Ministries of Health and donors may still choose to implement programs that are not the most efficient, but they should be called upon to provide stronger evidence of the importance of other considerations in that case.

Figure 1.
Figure 1.

Conceptual framework of the economics of trachoma.

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Figure 2.
Figure 2.

Number of cases of pre-visual impairment trichiasis per case of trachomatous blindness at which the burden from pre-visual impairment will equal the burden from trachomatous low vision and blindness for varying disability adjusted life year weights. Based on data in Frick and others.32

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Figure 3.
Figure 3.

Total potential productivity loss in billions ($5.3 billion 2003 U.S. dollars). Based on data in Frick and others.32

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Figure 4.
Figure 4.

Regional prevalence of trachomatous blindness by economic status sized by population. SSA = sub-Saharan Africa; CHI = China; OAI = Other Asia/Islands; IND = India; MEC = Middle Eastern Crescent.

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Figure 5.
Figure 5.

Division of dollars of lifetime cost of illness avoided by trichiasis surgery (1998 U.S. $89).5

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Figure 6.
Figure 6.

Costs of antibiotics and trichiasis surgery yielding zero net benefit.

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Figure 7.
Figure 7.

Realized potential gain and taxation combination that led to zero net cost for the government and donor from 2004 to 2020 with varying prices of azithromycin.

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 69, 5_suppl_1; 10.4269/ajtmh.2003.69.5_suppl_1.0690001

Authors’ addresses: Kevin D. Frick, Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway, Room 606, Baltimore MD 21205-1901, Telephone: 410-614-4018, Fax: 410-955-0470, E-mail: kfrick@jhsph.edu. Christy L. Hanson, PO Box 27794 Washington, DC 20038, Telephone: 202-458-2159, Fax: 202-473-8107, E-mail: chanson@jhsph.edu. Gretchen A. Jacobson, Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway, Room 654, Baltimore MD 21205-1901, Telephone: 410-955-6562, Fax: 410-955-0470, E-mail: gjacobso@jhsph.edu.

Acknowledgments: We thank Jeff Mecaskey for comments on an earlier version of this paper, his input on the concept of equity and trachoma, and his continued interest in the economics of trachoma.

Financial support: The work on this paper was supported by a grant from the International Trachoma Initiative.

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Author Notes

Reprint requests: Kevin D. Frick, Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway, Room 606, Baltimore MD 21205-1901.
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