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BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Cost effectiveness of strategies to combat vision and
hearing loss in sub-Saharan Africa and South East
Asia: mathematical modelling study
Rob Baltussen senior researcher 1, Andrew Smith honorary professor 2 1Department of Primary and Community Care, Radboud University Nijmegen Medical Center, PO Box 9101 6500HB Nijmegen, The Netherlands;2Centre for Disability and Development, London School of Hygiene and Tropical Medicine, London, UK relation to the economic attractiveness of other, existing or new, Objective To determine the relative costs, effects, and cost effectiveness
interventions in health.
of selected interventions to control cataract, trachoma, refractive error, hearing loss, meningitis and chronic otitis media.
Design Cost effectiveness analysis of or combined strategies for
Throughout the world, loss of vision and hearing are a major controlling vision and hearing loss by means of a lifetime population burden. More than 284 million people are visually impaired, of whom 245 million have low vision and 39 million are blind.1 Setting Two World Health Organization sub-regions of the world where
Some 278 million people worldwide have moderate or greater vision and hearing loss are major burdens: sub-Saharan Africa and hearing impairment.2-5 The number of people worldwide with South East Asia.
sensory deficits is rising mainly due to a growing global population and longer life expectancies. More than 90% of the Data sources Biological and behavioural parameters from clinical and
world's visually impaired people and 80% of hearing impaired observational studies and population based surveys. Intervention effects people live in low and middle income countries.1 6 and resource inputs based on published reports, expert opinion, and theWHO-CHOICE database.
Cataract is the leading cause of visual impairment globally, followed by glaucoma. The most common type of hearing Main outcome measures Cost per disability adjusted life year (DALY)
impairment is sensorineural hearing loss (with common causes averted, expressed in international dollars ($Int) for the year 2005.
advanced age and noise exposure), followed by conductive Results Treatment of chronic otitis media, extracapsular cataract surgery,
hearing impairment (with leading cause chronic otitis media).
trichiasis surgery, treatment for meningitis, and annual screening of Globally, up to 75% of all vision loss and 50% of hearing loss schoolchildren for refractive error are among the most cost effective interventions to control hearing and vision impairment, with the cost per For this reason, global initiatives have set targets and indicators DALY averted <$Int285 in both regions. Screening of both schoolchildren related to the reduction of vision and hearing impairment, with (annually) and adults (every five years) for hearing loss costs around special reference to low and middle income countries. VISION $Int1000 per DALY averted. These interventions can be considered 2020, the global initiative for the elimination of avoidable highly cost effective. Mass treatment with azithromycin to control blindness, aims to eliminate avoidable blindness by the year trachoma can be considered cost effective in the African but not the 2020 and prevent the projected doubling of avoidable visual South East Asian sub-region.
impairment between 1990 and 2020.7 WWHearing (World-Wide Conclusions Vision and hearing impairment control interventions are
Hearing Care for Developing Countries) aims to eliminate much generally cost effective. To decide whether substantial investments in of avoidable hearing loss by 2020 through a new initiative called these interventions is warranted, this finding should be considered in Correspondence to: R Baltussen [email protected] Extra material supplied b) General appendix (referred to by all the papers in this cluster)Appendices A–C: Details of (A) definitions of interventions, disease models, and resource use patterns; (B) costs, health effects, and cost effectivenessof all interventions; (C) probabilistic uncertainty analyses for interventions No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) For many countries, it is not evident that these targets will be achieved at current rates of progress, despite a wide range of Table shows the set of 87 analysed interventions (and effective interventions to prevent, detect, and manage visual combinations of interventions) to control cataract, trachoma, and hearing impairment. A key question, therefore, is whether refractive error, hearing loss, meningitis, or chronic otitis media.
the correct mix of interventions is currently being used, and We carefully selected the interventions on their relevance for what strategies should be scaled up if additional funds would disease control but were also limited by the lack of data on become available. Cost and cost effectiveness analyses can burden of disease or intervention effectiveness. Some provide valuable inputs to these decisions by identifying the interventions that have relatively recently been developed were most efficient ways of delivering prevention, diagnosis, and not subjected to analyses. The resulting set of interventions is treatment services at different levels of resource availability.
therefore somewhat arbitrary and not meant to cover all Several studies have reported on the global and regional cost potentially available interventions to reduce hearing and vision effectiveness of interventions targeting cataract,9 trachoma,10 loss in sub-Saharan Africa and South East Asia. For example, refractive error,11 and different causes of hearing impairment.12 in trachoma control we evaluated antibiotic treatment and However, studies have been carried out in isolation, which surgery but not promotion of face washing. Likewise, in cataract prevents the cost effectiveness of the different interventions control, we evaluated extracapsular cataract extraction but not being directly compared. In addition, the studies used small incision cataract surgery or phacoemulsification. In control demographics and price levels for the year 2000.
of hearing impairment, we did not evaluate education, Now, a decade past 2000, and in the realm of the global rehabilitation, and noise conservation programmes, nor neonatal initiatives, an up to date assessment of the cost effectiveness of screening, surgical interventions, or cochlear implants.
vision and hearing impairment control strategies is needed. In Interventions on glaucoma were also not evaluated. All this paper we address the question of what are the costs and interventions are defined in appendix A on bmj.com.
effects of prevention, early detection, management, and All interventions were analysed at WHO-CHOICE standardised rehabilitation of visual and hearing impairment, both singly and geographic coverage levels of 50%, 80%, and 95%, referring in combination. Our analysis is based on a consistent to the percentage of eligible cases receiving treatment. These methodological approach and a generic measure of effectiveness levels may not always be feasible, but are nevertheless reported and covers two geographical settings, in Asia and Africa.
here to show the presence of important (dis)economies of scale when varying the number of people covered.
Estimating health effects
The starting point of our analysis of health effects was the
Cost effectiveness analysis can be undertaken in many ways, identification of best available evidence on the (clinical or and there have been several attempts to develop methodological population) effectiveness of interventions. Ideally, we retrieved guidelines to make results more comparable. In its this evidence from Cochrane reviews (such as on the WHO-CHOICE project, the World Health Organization has effectiveness of cataract surgery), but in other instances we used developed a standardised set of methods and tools that can be evidence from individual studies (such as on the effectiveness used to analyse the societal costs and effectiveness of current of azithromycin in trachoma control). Where no evidence was and possible new interventions simultaneously.13 14 The project available, we based our estimate of effectiveness on expert is designed to provide regularly updated databases on the costs opinion (such as on levels of compliance in wearing hearing and the effects of a full range of promotive, preventive, curative, aids or glasses). We used evidence on intervention effectiveness and rehabilitative health interventions.
pertaining to the regions under study or extrapolated this from Western settings where meaningful (as for antibiotic treatment for meningitis). All sources of data of intervention effectiveness Most countries do not have the capacity to evaluate all potential for screening interventions for uncorrected refractive error are interventions for improving given health indicators at the listed in table 3, and those for the other disease areas are listed national and the sub-national level, and global estimates are too in the appendices on bmj.com.
general and of little use to any specific country. However, All analyses used population model PopMod19 to translate this countries may benefit from regional evaluations of data, where intervention effectiveness into a generic measure of health data of neighbouring countries with similar settings are pooled.
effects. More specifically, it combines incidence, prevalence, The present analysis drew on a comprehensive examination of and mortality data for the relevant causes of vision and hearing 14 world sub-regions defined by geographical proximity and impairment with the standard health state valuations20 to estimate epidemiology according to WHO classification. In common the population impact of the different scenarios in terms of with other papers in this series, we evaluated interventions for healthy years lived.14 Following standardised WHO-CHOICE two major global regions using a standardised analytical cost effectiveness analysis, we evaluated all interventions for a approach. The two regions are referred to as sub-Saharan Africa, period of 10 years, and ran model for the length of time including those African countries with very high adult and high necessary for all people affected by the interventions to have child mortality (referred to as AfrE in the WHO classification), died (that is, some 100 years in both regions, following the use and South East Asia, including those countries in Asia with high of regional mortality rates18). The difference between the healthy adult and high child mortality (referred to as SearD).15 The years lived in each intervention scenario and the no intervention prevalence of vision and hearing impairment globally and for scenario is the health gain of the intervention, or the number of these two regions is summarised in table (based on Resnikoff disability adjusted life years (DALYs) averted. A general et al16 17 and Mathers18).
description of the population model is provided in the general appendix on bmj.com, and details of the different disease models are available in appendix A on bmj.com.
No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) both more effective and less costly than other interventions. We The analysis follows standardised WHO-CHOICE guidelines then calculated the incremental cost effectiveness ratio for those on costing analysis, and estimates patient level costs and resulting interventions by dividing the incremental costs by the programme level costs from the societal perspective. Patient incremental health effects. The economic attractiveness of an level costs are all costs incurred at the level of contact between intervention within its disease area is reflected by this the provider and the individual patient. The quantities of incremental cost effectiveness ratio: the lower the incremental resources required in terms of diagnostic tests, drug use, and cost per DALY averted, the more economically attractive an health centre visits for supervision and monitoring and intervention is. Thirdly, we compared resulting interventions hospitalisation for each of the interventions were based on WHO across disease areas on the basis of their incremental cost treatment protocols and expert opinion of actual practice. Drug effectiveness ratios and ranked them accordingly. The costs were based on international drug prices21 with a mark up interventions with the lowest incremental cost effectiveness for international and local transportation costs.22 23 Unit costs ratio are ranked highest and are economically most attractive.
of health centre visits and hospital inpatient days were based WHO-CHOICE defines interventions that have an incremental on econometric analysis by Adam et al,24 while those for cost effectiveness ratio of less than the gross domestic product laboratory tests and x rays were based on the best available (GDP) per capita as very cost effective, and those with a ratio international cost information included in WHO-CHOICE's less than three times the GDP per capita as cost effective. The costing database. Unit costs were combined with resource use regions studied here have a GDP of around $Int2000 per capita,30 patterns to estimate the cost per patient treated. Total patient which means that interventions costing <$Int2000 per DALY costs were then calculated as the cost per patient treated averted can be considered very cost effective and those costing multiplied by the number of patients treated (calculated as the between $Int2000 and $Int6000 can be considered cost effective.
annual incidence of disease from the model multiplied by the Other interventions are considered not cost effective.
relevant coverage level and then by the percentage of cases diagnosed and treated in covered areas). The costs of screening interventions to detect hearing and vision impairment not only All interventions are imbued with a certain degree of uncertainty.
include the costs of the screening activities but also costs of To handle this aspect of reporting for such a wide range of hearing aids and glasses for those who need them.
interventions, we classified interventions according to their Programme level costs relate to the resource inputs used in the degree of cost effectiveness (not cost effective, cost effective, production of an intervention at a level above that of the patient or very cost effective) in order to ascertain order of magnitude or providing facility, such as central planning and administration differences in cost effectiveness. In addition, we undertook a functions, supervision, and training. Estimated quantities of probabilistic uncertainty analysis using MCLeague software31 resources required for central planning and administration at to assess the impact of alternative assumptions on costs and national, provincial and district levels were based on a series of effects (which were each varied with plus and minus 25% of evaluations made by WHO-CHOICE costing experts in the their baseline values) on the classification of interventions.
different sub-regions and validated against the literature (categories of resource input included personnel, training, materials and supplies, media, transport, maintenance, utilities and capital.22 Details of all cost calculations are found in A few modifications were made to previously published appendix A on bmj.comand previously published papers.9-12 An analyses.9-12 Firstly, interventions were considered during the example of all variable inputs including its sources is provided 10 year period 2005to 2015 rather than the period 2000–10, and in table 3for the cost effectiveness analysis of screening costs were reported at price levels for year 2005 instead of 2000.
strategies for uncorrected refractive error among schoolchildren Secondly, because of variations in the reporting of coverage in sub-Saharan Africa.
levels in previous studies, interventions were evaluated at standardised geographic coverage levels of 50%, 80%, and 95%.
Following the WHO-CHOICE standardised approach, we Thirdly, assumptions on screening, patient, training, and assumed that interventions were performed optimally (that is, intervention programme costs were revisited to make results no undertreatment or overtreatment at the highest efficiency consistent across the analysis. For example, recent price level).14 All costs were reported in international dollars ($Int) reductions of azithromycin after patent expiry were included in for the year 2005 to facilitate more meaningful comparisons the analysis on trachoma control.
across regions ($Int1 buys the same quantity of healthcare resources in the sub-Saharan African and South East Asian regions as it does in the United States). For example, cost estimates in sub-Saharan Africa in $Int should be divided by a Following the stepwise approach to the rank ordering of factor 2.3 to obtain US$ cost estimates for Kenya (in South East interventions on the basis of their cost effectiveness, we first Asia cost estimates should be divided by a factor 3.1 to obtain report the average cost effectiveness ratios of all interventions US$ cost estimates for India).15 All costs and effects are within each disease area (appendix table B1 on bmj.com).
discounted at 3%, following standardised WHO-CHOICE Second, we report the incremental cost effectiveness ratios for those interventions that both cost less and provide more health Estimating cost effectiveness
effects than other interventions, and these indicate the economic attractiveness of interventions within each disease area (same We rank ordered interventions on the basis of their cost effectiveness in a number of standardised steps.14 Firstly, within In trachoma control, trichiasis surgery is the most cost effective each disease area, we calculated the average cost effectiveness intervention, followed by mass treatment with azithromycin in ratios for every intervention by dividing its total number of both regions. Both mass treatment with tetracycline ointment DALYs averted by its total costs. Secondly, again within each and targeted treatment with azithromycin are not cost effective.
disease area, we considered only those interventions that were In cataract control, extracapsular cataract surgery dominates No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) intracapsular surgery in both regions. In both regions, passive cost effective. Mass treatment with azithromycin to control screening of children and adults for hearing disorders (in trachoma can be considered cost effective in the sub-Saharan combination with provision of hearing aids) is most cost African but not the South East Asian region.
effective, followed by screening of adults every five years and annual screening of primary and secondary school children.
Strengths and limitations
Screening of adults every 10 years is not cost effective. For treatment of chronic otitis media, treatment with topical The analysis has several limitations. Firstly, we performed our antibiotics is the most cost effective intervention in both regions.
analysis at the regional level, but important differences in costs For screening for refractive error (including the provision of or effectiveness of interventions may exist between countries spectacles), screening of all primary and secondary school in the same region. Since decision making is made at the country children is most cost effective in sub-Saharan Africa. In South (as opposed to regional) level, more refined estimates of costs, East Asia, screening of secondary school children is most cost effects, and cost effectiveness should be made at the country effective, followed by screening of both primary and secondary level, based on country-specific data. A good example is the school children.
contextualisation of WHO-CHOICE regional results to the country level in Mexico, as reported in this series.32 In a third step, we rank interventions according to their incremental cost effectiveness ratio across all disease areas Secondly, assumptions on intervention effectiveness are based (tables and for sub-Saharan Africa and South East Asia).
on a variety of sources and may reflect contexts other than the This is illustrated in the figurefor sub-Saharan Africa.
regions analysed—the same level of effectiveness may not Implementation of all cost effective interventions would cost always be realised in reality, and results should be interpreted around $Int19 per capita in sub-Saharan Africa.
with caution. Yet, our probabilistic uncertainty analysis indicates that our study results are robust to alternative assumptions.
In both regions treatment of chronic otitis media with topical These issues are discussed in detail in previously published antibiotics is the most cost effective intervention, with an average cost per DALY averted of <$Int63 at all levels. In sub-Saharan Africa the next most cost effective interventions Thirdly, we did not evaluate all possible interventions that could are trichiasis surgery, extracapsular cataract surgery, annual reduce vision or hearing loss, and our choice of interventions screening of all primary and secondary school children for is somewhat arbitrary. Policymakers should be aware of this, refractive error, and treatment for meningitis with ceftriaxione.
and should not limit their choice of interventions to those In South East Asia the next most cost effective interventions included in this analysis.
are treatment of meningitis with ceftriaxione, extracapsular Fourthly, and more specifically, we evaluated screening for cataract surgery, screening of all primary and secondary school hearing disorders as carried out by trained primary health children for refractive error, and trichiasis surgery. In both workers (incurring healthcare costs), and screening for refractive regions these interventions all cost <$Int285 per DALY averted error as carried out by trained school teachers (who incur no (incremental cost effectiveness ratio, with the exact order of healthcare costs). However, alternative assumptions have only interventions dependent on coverage level). In both regions limited impact on study results.
introducing screening for hearing impairment in combination Fifthly, in the absence of reliable data, we did not include time with the delivery of hearing aids, at 80% coverage level costs costs of people seeking and undergoing care, nor did we include around $Int1000 per DALY averted. According to changes in productivity losses as a result of the interventions.
WHO-CHOICE benchmark on cost effectiveness, these The perspective of analysis is therefore not truly societal.
interventions can all be considered very cost effective. Mass Inclusion of productivity gains after reductions in vision and treatment with azithromycin is the least cost effective hearing loss would render the interventions more cost effective.
intervention in both regions but can, depending on the coverage Sixthly, we assumed that all interventions were implemented level, still be considered cost effective in the sub-Saharan at a relatively high efficiency level—which allows an equal African region. In the absence of any budgetary constraint comparison between the cost effectiveness of interventions and implementation of all interventions would lead to a total health avoids the complications from interventions that were not gain of up to 32 million DALYs in sub-Saharan Africa and 84 implemented well would be disadvantaged in comparison with million DALYs in South East Asia.
those that were well implemented.
The probabilistic uncertainty analysis depicted in appendix C Lastly, the analysis evaluates interventions at 50%, 80%, and on bmj.com shows the impact of plausible variations in total 95% geographic coverage levels, following standardised costs and total effects and shows that the average cost WHO-CHOICE methodology. The higher coverage levels may effectiveness ratios of most interventions would retain their not always be achievable but are included to indicate the classification of highly cost effective or cost effective after economies of scale that may take place when more people are taking into account such uncertainty. A similar logic would reached with an intervention.23 apply to the incremental cost effectiveness ratio.
The above limitations should be considered in the overall aim of WHO-CHOICE analysis to provide broad indications on the cost effectiveness of a range of interventions to inform general policy discussions, rather than to deliver precise estimates on a specific intervention.15 Treatment of chronic otitis media, extracapsular cataract surgery, trichiasis surgery, treatment for meningitis, and annual screening Study strengths include the use of disease models that have of school children for refractive error are among the most cost already been published and applied, consideration of effective interventions available to control hearing and vision combinations of interventions, use of a generic measure of impairment, with the cost per DALY averted <$Int285 in both effectiveness, and testing of important assumptions through regions. Screening of both schoolchildren (annually) and adults (every five years) for hearing loss costs around $Int1000 per DALY averted. These interventions can be considered highly No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Comparison with other studies
World Health Organization. Fact sheet—magnitude and causes of visual impairment .
This study includes a number of modifications in comparison Mathers C, Smith A, Concha M. Global burden of hearing loss in the year 2000 . WHO, to the previously published analysis. The higher 2005 price Mathers C, Smith A, Concha M. Global burden of adult-onset hearing loss in the year levels have generally resulted in higher cost effectiveness ratios, 2002 . WHO, 2005.
but these and other modifications have generally not changed Smith A, Mathers C. Epidemiology of infection as a cause of hearing loss. In: Newton VE, Vallely PJ, eds. Infection and hearing impairment . John Wiley, 2006.
study conclusions. The exception is mass or targeted treatment Mackenzie I, Smith A. Deafness—the neglected and hidden disability. Ann Trop Med with azithromycin in trachoma control, where price reductions of azithromycin have offset general price increases in the period World Health Organization. Fact sheet—deafness and hearing impairment . WHO, 2011.
from 2000 to 2005 and have thus rendered the interventions Vision 2020. Global initiative for the elimination of avoidable blindness. 2011. more cost effective.
World Health Organisation, World Wide Hearing 2009. Seventh workshop on provision of hearing aids and services for developing countries and WWHearing General Assembly.
Report of workshop and general assembly. 12-13 November 2009. WHO, 2009.
Baltussen R, Sylla M, Mariotti SP. Cost-effectiveness analysis of cataract surgery: a global Our results have four major policy implications. Firstly, they and regional analysis. Bull World Health Organ 2004;82:338-45.
10 Baltussen RM, Sylla M, Frick KD, Mariotti SP. Cost-effectiveness of trachoma control in reinforce the fact that cataract surgery and treatment of chronic seven world regions. Ophthalmic Epidemiol 2005;12:91-101.
otitis media are among the key interventions for combating 11 Baltussen R, Naus J, Limburg H. Cost-effectiveness of screening and correcting refractive errors in school children in Africa, Asia, America and Europe. Health Policy 2009;89:201-15.
vision and hearing impairment.
12 Baltussen R, Smith A. Cost-effectiveness of hearing impairment control in Africa and Asia: Secondly, they show that there is a strong economic case to a mathematical modelling approach. Int J Audiol 2009;48:144-58.
13 Hutubessy R, Chisholm D, Edejer TT. Generalized cost-effectiveness analysis for consider screening for refractive error among schoolchildren.
national-level priority-setting in the health sector. Cost Eff Resour Alloc 2003;1:8 This supports current efforts within the VISION 2020 initiative 14 Tan Torres, T, Baltussen RM, Adam T, Hutubessy RC, Acharya A, Evans DB. WHO guide to cost-effectiveness analysis . WHO, 2003.
to give greater prominence to screening programmes. Screening 15 Evans DB, Lim SS, Adam T, Tan-Torres Edejer T, the WHO-CHOICE MDG Team.
schoolchildren and adults for hearing disorders is somewhat Achieving the Millennium Development Goals for health: a re-examination of intervention strategies. BMJ 2005;331:1457-61.
less cost effective but is still economically attractive according 16 Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, Pokharel GP, et al.
to commonly used benchmarks.
Global data on visual impairment in the year 2002. Bull World Health Organ Thirdly, inclusion of mass treatment with azithromycin in 17 Resnikoff S, Pascolini D, Mariotti SP, Pokharel GP. Global magnitude of visual impairment programmes to eliminate trachoma needs careful analysis: caused by uncorrected refractive errors in 2004. Bull World Health Organ 2008;86:63-70.
18 World Health Organisation. The global burden of disease: 2004 update . Available at: although the intervention was cost effective in sub-Saharan Africa according to commonly used benchmarks, it was not in 19 Lauer JA, Murray CJL, Roehrich K, Wirth H. PopMod: a longitudinal four-state population model with two disease states and comorbidity. Cost Eff Resour Alloc 2003;1:6.
South East Asia. However, many programmes around the world 20 Murray CJL, Lopez A. Global burden of disease . World Bank, WHO, Harvard University, use donated azithromycin, which makes the intervention 21 International drug price indicator guide. Introduction. 2011. economically more attractive than we have reported here. In our analysis, trichiasis surgery is more cost effective and thus 22 Johns B, Baltussen R, Adam T, Hutubessy RCW. Programme costs in the economic provides better value for money.
evaluation of health interventions. Cost Eff Resour Alloc 2003;1:1.
23 Johns B, Baltussen R. Accounting for the costs of scaling up health interventions. Health Fourth, our results show that substantial health gains can be 24 Adam T, Evans DB, Murray CJL. Econometric estimation of country-specific hospital achieved—up to 32 and 84 million DALYs averted in costs. Cost Eff Resour Alloc 2003;1:3.
sub-Saharan Africa and South East Asia respectively, when 25 Unicef. Database on school enrolment. 2008. available effective interventions are scaled up. This will require 26 Murray CJL, Lopez AD. The global burden of disease: a comprehensive assessment of major resource mobilisation efforts at domestic and international mortality and disability from diseases, injuries, and risk factors in 1990 and projected to level. Yet, whether such substantial investments are warranted 2020. Harvard University Press, 1996.
27 Limburg H, Kansara HT, d'Souza S. Results of school eye screening of 5.4 million children can only be judged when the findings our present study—that in India—a five-year follow-up study. Acta Ophthalmol Scand 1999;77:310-4.
vision and hearing impairment control interventions are 28 Hogeweg M, Sapkota YD, Foster A. Acceptability of aphakic correction. Results from Karnali eye camps in Nepal. Acta Ophthalmologica 1992;70:407-12.
generally cost effective—are considered in relation to the 29 Limburg H, Vaidyanathan K, Dalal HP. Cost-effective screening of schoolchildren for economic attractiveness of other, existing or new, interventions refractive errors. World Health Forum 1995;16:173-8.
30 Hutubessy RC, Baltussen RM, Evans DB, Barendregt JJ, Murray CJ. Stochastic league in health. For this broader analysis, we refer to Evans et al15 and tables: communicating cost-effectiveness results to decision-makers. Health Econ Chisholm et al,33 who compare the economic attractiveness of a wide range of interventions to control, respectively, 31 Salomon J, Carvalho N, Gutierrez-Delgado C, Casey A, Hogan DR, Lee D, et al.
Intervention strategies to reduce burden of non-communicable diseases in Mexico: cost communicable and non-communicable diseases.
effectiveness analysis. BMJ 2012;344:e355.
32 Chisholm D, Baltussen, Evans DB, Ginsberg G, Lauer J, Lim S, et al. What are the priorities for prevention and control of non-communicable diseases and injuries in sub-Saharan Contributors: Both authors contributed to the conception, design and Africa and South East Asia? BMJ 2012;344:e586.
33 Congdon N, Zheng M, Sharma A, Choi K, Song Y, Zhang M, et al. Prevalence and interpretation of data, and drafting of the manuscript. RB performed the determinants of spectacle nonwear among rural Chinese secondary schoolchildren: the technical analysis. Both authors approved the submitted version of the Xichang Pediatric Refractive Error Study Report 3. Arch Ophthalmol 2008;126:1717-23.
manuscript. RB is the guarantor of the manuscript.
34 Vincent JE, Netek S, Parry A, Mladenovich D, Thein NN, Amendola PR. Reported wearing compliance of ready-made spectacles at 6 and 12 months. Optom Vis Sci 2010;87:958-65.
Competing interests: All authors have completed the Unified Competing Accepted: 12 October 2011
Interest form at (available on requestfrom the corresponding author) and declare: no support from any Cite this as: BMJ 2012;344:e615 organisation for the submitted work; no financial relationships with any This is an open-access article distributed under the terms of the Creative Commons organisations that might have an interest in the submitted work in the Attribution Non-commercial License, which permits use, distribution, and reproduction in previous three years, no other relationships or activities that could appear any medium, provided the original work is properly cited, the use is non commercial and to have influenced the submitted work.
is otherwise in compliance with the license. See: Ethical approval: Ethical approval was not required for this study.
Data sharing: No additional data available No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) What is already known on this topic
Several studies have reported on the global and regional cost effectiveness of interventions targeting cataract, trachoma, refractive error and different causes of hearing impairment.
However, studies have been carried out in isolation, which prevents the cost effectiveness of the different interventions in visual and hearing impairment control being directly compared.
In addition, these studies have been analysed using year 2000 demographics and price levels What this study adds
This study directly compares cost and effects of interventions targeting cataract, trachoma, refractive error and different causes of hearing impairment, using more recent price levels in Sub-Saharan Africa and South East AsiaThis allows the identification of most efficient strategies to reduce vision and hearing loss Table 1 Prevalence of vision and hearing loss in WHO sub-Saharan African sub-region AfrE, South East Asian sub-region SearD, and the
world (2004 estimates). Values are millions of people (percentages)
Total population* Age related macular degeneration Corneal opacities Diabetic retinopathy Childhood blindness Uncorrected refractive error‡ Uncorrected refractive error Moderate or greater hearing impairment*
Adult onset
*Based on 2004 burden of disease estimates.18†Based on Resnikoff et al.1617 Figures relate to year 2004 and do not match with figures on year 2010 as provided in main text (the latter figures are not yet availableby cause).
‡Estimates in absolute numbers are for ages ≥50 years. Percentages are compared with total population of all ages.
No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Table 2 List of interventions considered in cost effectiveness analysis of strategies to combat vision and hearing loss in WHO sub-Saharan
African sub-region AfrE and South East Asian sub-region SearD
Mass treatment tetracycline ointment (50% coverage) Mass treatment azithromycin (50% coverage) Targeted treatment azithromycin (50% coverage) Trichiasis surgery (50% coverage) Mass treatment tetracycline ointment + trichiasis surgery (50% coverage) Mass treatment azithromycin + trichiasis surgery (50% coverage) Targeted treatment azithromycin + trichiasis surgery (50% coverage) Mass treatment tetracycline ointment (80% coverage) Mass treatment azithromycin (80% coverage) Targeted treatment azithromycin (80% coverage) Trichiasis surgery (80% coverage) Mass treatment tetracycline ointment + trichiasis surgery (80% coverage) Mass treatment azithromycin + trichiasis surgery (80% coverage) Targeted treatment azithromycin + trichiasis surgery (80% coverage) Mass treatment tetracycline ointment (95% coverage) Mass treatment azithromycin (95% coverage) Targeted treatment azithromycin (95% coverage) Trichiasis surgery (95% coverage) Mass treatment tetracycline ointment + trichiasis surgery (95% coverage) Mass treatment azithromycin + trichiasis surgery (95% coverage) Targeted treatment azithromycin + trichiasis surgery (95% coverage) Extracapsular cataract extraction with posterior chamber lens implant (50% coverage) Extracapsular cataract extraction with posterior chamber lens implant (80% coverage) Extracapsular cataract extraction with posterior chamber lens implant (95% coverage) Screening for hearing loss†
HEA-1
Annual screening primary school children (50% coverage) Annual screening secondary school children (50% coverage) Annual screening primary and secondary school children (50% coverage) Screening adults every 5 years (50% coverage) Screening adults every 10 years (50% coverage) Passive screening all children and adults (50% coverage) Annual screening primary school children + screening adults every 5 years (50% coverage) Annual screening primary school children + screening adults every 10 years (50% coverage) Annual screening secondary school children + screening adults every 5 years (50% coverage) Annual screening secondary school children + screening adults every 10 years (50% coverage) Annual screening primary and secondary school children + screening adults every 5 years (50% coverage) Annual screening primary and secondary school children + screening adults every 10 years (50% coverage) Annual screening primary school children (80% coverage) Annual screening secondary school children (80% coverage) Annual screening primary and secondary school children (80% coverage) Screening adults every 5 years (80% coverage) Screening adults every 10 years (80% coverage) Passive screening all children and adults (80% coverage) Annual screening primary school children + screening adults every 5 years (80% coverage) Annual screening primary school children + screening adults every 10 years (80% coverage) Annual screening secondary school children + screening adults every 5 years (80% coverage) No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Table 2 (continued)
Annual screening secondary school children + screening adults every 10 years (80% coverage) Annual screening primary and secondary school children + screening adults every 5 years (80% coverage) Annual screening primary and secondary school children + screening adults every 10 years (80% coverage) Annual screening primary school children (95% coverage) Annual screening secondary school children (95% coverage) Annual screening primary and secondary school children (95% coverage) Screening adults every 5 years (95% coverage) Screening adults every 10 years (95% coverage) Passive screening all children and adults (95% coverage) Annual screening primary school children + screening adults every 5 years (95% coverage) Annual screening primary school children + screening adults every 10 years (95% coverage) Annual screening secondary school children + screening adults every 5 years (95% coverage) Annual screening secondary school children + screening adults every 10 years (95% coverage) Annual screening primary and secondary school children + screening adults every 5 years (95% coverage) Annual screening primary and secondary school children + screening adults every 10 years (95% coverage) Ceftriaxione (50% coverage) Ceftriaxione (80% coverage) Ceftriaxione (95% coverage) Chronic otitis media control
COM-1
Aural toilet (50% coverage) Topical antibiotics (50% coverage) Aural toilet (80% coverage) Topical antibiotics (80% coverage) Aural toilet (95% coverage) Topical antibiotics (95% coverage) Annual screening all primary school children (50% coverage) Annual screening all secondary school children (50% coverage) Annual screening all primary and secondary school children (50% coverage) Annual screening children 8 years old (50% coverage) Annual screening children 13 years old (50% coverage) Annual screening children 8 and 13 years old (50% coverage) Annual screening all primary school children (80% coverage) Annual screening all secondary school children (80% coverage) Annual screening all primary and secondary school children (80% coverage) Annual screening children 8 years old (80% coverage) Annual screening children 13 years old (80% coverage) Annual screening children 8 and 13 years old (80% coverage) Annual screening all primary school children (95% coverage) Annual screening all secondary school children (95% coverage) Annual screening all primary and secondary school children (95% coverage) Annual screening children 8 years old (95% coverage) Annual screening children 13 years old (95% coverage) Annual screening children 8 and 13 years old (95% coverage) *Coverage level relates to the geographic coverage of these eligible for intervention.
†Screening for hearing loss is in combination with the provision of hearing aids to those who need it.
‡Screening for uncorrected refractive error is in combination with the provision of spectacles to those who need it.
No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Table 3 Model inputs for cost effectiveness analysis of screening strategies for uncorrected refractive error in schoolchildren in WHO
sub-Saharan African sub-region AfrE
Data source
Target population
Primary school enrolment rate
Secondary school enrolment rate Health effects
Health state valuation of visual impairment
Burden of disease study26 Remission rate of uncorrected refractive error (without screening or treatment)Remission rate of uncorrected refractive error (intervention scenarios) Compliance with wearing provided glassess Assumption based on Limburg et al27 in India; Hogeweg et al28 in Nepal‡ No of children to screen per teacher (5–10 years old) Limburg et al29 in India¶ No of children to screen per teacher (8 years old) No of children to screen per teacher (11–15 years old) No of children to screen per teacher (13 years old) Duration of training (days) Repetition of training (every number of years) Cost per teacher to train (cost per day) Ratio of true positive:false positive cases Limburg et al29 in India¶ Useful life of glasses (years) Screening material costs (tape, card etc) Treatment at health clinic: Cost of ophthalmic assistant: Time spent per patient (minutes) Costs of ophthalmic equipment: Useful life (years) Average annual patient load Costs of spectacles: Useful life (years) Costs of outpatient visits: Limburg et al29 in India¶ Costs of visits at secondary hospital level *Based on personal communication with Dr Mariotti (WHO) and Dr Limburg (independent consultant), both specialists in ophthalmology in low and middle incomesettings.
†Formula is −LN(1−(effectiveness×coverage)), with effectiveness equal to compliance and coverage as defined in intervention. The table lists the remission ratefor a coverage of 95%.
‡Estimates based on two studies in the respective regions, and are in line with findings from other studies in China34 and Thailand.35§The number of teachers to train depends on the number of schoolchildren that one teacher can screen and, ultimately, on school size. In screening of childrenaged 5–10 years, a trained teacher can serve all classes in the school, on average 165 children. In case only children of aged 8 years are screened, the teachercan screen only that class, on average 50 children. The same logic applies to screening at secondary school.
¶To our knowledge, this is the only study that provides the required details on costs of screening for refractive error in a low income setting and has therefore beenused as the basis for our estimates.
No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Table 4 Cost effectiveness of strategies to combat vision and hearing loss in WHO sub-Saharan African sub-region AfrE
Annual DALYs
Cost effectiveness ratio
Annual cost per
saved per million
Disease area and intervention
Coverage (%)
COM-2: Chronic otitis media, topical antibiotics COM-4: Chronic otitis media, topical antibiotics COM-6: Chronic otitis media, topical antibiotics TRA-11: Trachoma, trichiasis surgery CAT-4: Cataract, extracapsular cataract extraction with posterior chamber lens implantCAT-6: Cataract, extracapsular cataract extraction with posterior chamber lens implantTRA-18: Trachoma, trichiasis surgery RE-9: Uncorrected refraction error, annual screening of all schoolchildren‡MEN-1: Meningitis, ceftriaxione RE-15: Uncorrected refraction error, annual screening of all schoolchildren‡HEA-6: Hearing loss, passive screening of all children and adults§HEA-18: Hearing loss, passive screening of all children and adults§HEA-4: Hearing loss, screening of adults every 5 years§HEA-16: Hearing loss, screening of adults every 5 years§MEN-2: Meningitis, ceftriaxione HEA-23: Hearing loss, annual screening of schoolchildren + screening of adults every 5 years§TRA-20: Trachoma, mass treatment with azithromycin + trichiasis surgeryMEN-3: Meningitis, ceftriaxione HEA-35: Hearing loss, annual screening of school children + screening of adults every 5 years§ DALYs=disability adjusted life years. $Int=international dollars.
*$Int per DALY averted relative to no intervention.
†$Int per DALY averted, within intervention cluster. This measures the increase in cost divided by the increase in effects when a new intervention is added to anexisting intervention. For example, the incremental cost per DALY averted for screening primary and secondary school children for refractive error is the totalincrease in cost divided by the total increase in DALYs averted when screening of primary school children is added to the existing screening of secondary schoolchildren. Incremental ratios are only shown for interventions that are both more effective and less costly than other interventions.
‡Screening for uncorrected refractive error is in combination with the provision of spectacles to those who need it.
§Screening for hearing loss is in combination with the provision of hearing aids to those who need it.
No commercial reuse: See rights and reprints BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Table 5 Cost effectiveness of strategies to combat vision and hearing loss in WHO South East Asian sub-region SearD
Annual DALYs
Cost effectiveness ratio
Annual cost per
saved per million
Disease area and intervention
Coverage (%)
COM-2: Chronic otitis media, topical antibiotics COM-4: Chronic otitis media, topical antibiotics COM-6: Chronic otitis media, topical antibiotics MEN-1: Meningitis, ceftriaxione CAT-6: Cataract, extracapsular cataract extraction with posterior chamber lens implantMEN-2: Meningitis, ceftriaxione RE-2: Uncorrected refraction error, annual screening of all secondary school children‡RE-8: Uncorrected refraction error, annual screening of all secondary school children‡RE-9: Uncorrected refraction error, annual screening of all schoolchildren‡MEN-3: Meningitis, ceftriaxione TRA-11: Trachoma, trichiasis surgery RE-15: Uncorrected refraction error, annual screening of all schoolchildren‡HEA-6: Hearing loss, passive screening of all children and adults§TRA-18: Trachoma, trichiasis surgery HEA-18: Hearing loss, passive screening of all children and adultsHEA-11: Hearing loss, annual screening of schoolchildren + screening of adults every 5 years§HEA-23: Hearing loss, annual screening of schoolchildren + screening of adults every 5 years§HEA-35: Hearing loss, annual screening of school children + screening of adults every 5 years§TRA-20: Trachoma, mass treatment with azithromycin + trichiasis surgery DALYs=disability adjusted life years. $Int=international dollars.
*$Int per DALY averted relative to no intervention.
†$Int per DALY averted, within intervention cluster. This measures the increase in cost divided by the increase in effects when a new intervention is added to anexisting intervention. For example, the incremental cost per DALY averted for screening primary and secondary school children for refractive error is the totalincrease in cost divided by the total increase in DALYs averted when screening of primary school children is added to the existing screening of secondary schoolchildren. Incremental ratios are only shown for interventions that are both more effective and less costly than other interventions.
‡Screening for hearing loss is in combination with the provision of spectacles to those who need it.
§Screening for uncorrected refractive error is in combination with the provision of hearing aids to those who need it.
No commercial reuse: See rights and reprints

BMJ 2012;344:e615 doi: 10.1136/bmj.e615 (Published 2 March 2012) Incremental cost effectiveness ratios and cumulative cost per capita ($Int) of interventions to combat vision and hearing loss in WHO sub-Saharan African sub-region AfrE. Cost per DALY averted (bars) ranges from very cost effective (such as treatment of chronic otitis media with topical antibiotics at 50% coverage (COM-2) costing $Int16 per DALY averted) to least cost effective (annual screening of schoolchildren and screening of adults every five years for hearing loss (HEA-35) costing $Int3639 per DALY averted). Cumulative cost per capita (dashed line) shows cost if interventions are implemented in order of decreasing economic attractiveness. In case only COM-2 is implemented, cost per capita is $Int0.01. If all shown interventions are implemented, costs per capita increase to $Int14.86. See table 4for descriptions of the intervention No commercial reuse: See rights and reprints

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