Cost-effectiveness of community-wide treatment for helminthiasis – Authors' reply

We are delighted by the interest in our study of the cost-effectiveness of expanded community-wide treatment against schistosomiasis and soil-transmitted helminthiasis.1Lo NC Bogoch II Blackburn BG et al.Comparison of community-wide, integrated mass drug administration strategies for schistosomiasis and soil-transmitted helminthiasis: a cost-effectiveness modelling study.Lancet Glob Health. 2015; 3: e629-e638Summary Full Text Full Text PDF Scopus (79) Google Scholar In response to the critique by Hugo Turner and colleagues, we offer the following points for consideration. First, the use of binary disability weights for schistosomiasis is conservative, standard practice, and used by the Global Burden of Diseases study,2Salomon JA Vos T Hogan DR et al.Common values in assessing health outcomes from disease and injury: disability weights measurement study for the Global Burden of Disease Study 2010.Lancet. 2012; 380: 2129-2143Summary Full Text Full Text PDF PubMed Scopus (918) Google Scholar among others. Although we agree that better data is needed to inform disability as a function of schistosomiasis burden, we employed these conventional disability weights because such data are limited and we recognised disability even at low disease burden.3King CH It's time to dispel the myth of “asymptomatic” schistosomiasis.PLoS Negl Trop Dis. 2015; 9: e0003504Google Scholar Importantly, the use of a binary disability weight is in fact conservative with respect to cost-effectiveness, since no treatment benefit is given unless an infection is cured. Indeed, recalculation with intensity-stratified disability weights reveals that community-wide treatment is even more cost effective (table; methods are further detailed in the appendix).4King CH Dickman K Tisch DJ Reassessment of the cost of chronic helmintic infection: a meta-analysis of disability-related outcomes in endemic schistosomiasis.Lancet. 2005; 365: 1561-1569Summary Full Text Full Text PDF PubMed Scopus (701) Google Scholar, 5King CH Olbrych SK Soon M Singer ME Carter J Colley DG Utility of repeated praziquantel dosing in the treatment of schistosomiasis in high-risk communities in Africa: a systematic review.PLoS Negl Trop Dis. 2011; 5: e1321Crossref PubMed Scopus (105) Google Scholar Second, concern is raised over our use of a constant relation between parasitic worm burden and egg production from one helminth species to another. We tested alternative species-specific values for this poorly measured parameter and found that our results are highly robust (appendix).TableIncremental cost-effectiveness ratio (US$ per DALY averted) of strategies for integrated mass drug administration targeting schistosomiasis and soil-transmitted helminthiasis using intensity-stratified disability weight for schistosomiasisBinary weightStratified weightsSchool-aged children*Relative to no treatment.11898Community-wide†Relative to treatment of school-aged children.167145DALY=disability-adjusted life year. A lower incremental cost-effectiveness ratio is more cost effective, and an intervention was considered highly cost effective if the incremental cost-effectiveness ratio was less than US$1521 per DALY.* Relative to no treatment.† Relative to treatment of school-aged children. Open table in a new tab DALY=disability-adjusted life year. A lower incremental cost-effectiveness ratio is more cost effective, and an intervention was considered highly cost effective if the incremental cost-effectiveness ratio was less than US$1521 per DALY. Taken together, the two methodological issues did not affect our results or conclusions. Turner and colleagues further speculate that community-wide treatment might not be necessary in regions that are highly endemic for only Trichuris trichiura and Ascaris lumbricoides in school-aged children, which provides a hypothetical epidemiological situation to illustrate their argument. In reality, hookworm and schistosomiasis—with an age distribution that greatly affects adults—are frequently co-endemic with T trichiura and A lumbricoides.6Karagiannis-Voules DA Biedermann P Ekpo UF et al.Spatial and temporal distribution of soil-transmitted helminth infection in sub-Saharan Africa: a systematic review and geostatistical meta-analysis.Lancet Infect Dis. 2015; 15: 74-84Summary Full Text Full Text PDF PubMed Scopus (120) Google Scholar, 7Lai YS Biedermann P Ekpo UF et al.Spatial distribution of schistosomiasis and treatment needs in sub-Saharan Africa: a systematic review and geostatistical analysis.Lancet Infect Dis. 2015; 15: 927-940Summary Full Text Full Text PDF PubMed Scopus (136) Google Scholar Furthermore, T trichiura and A lumbricoides do affect adult populations and are thus not confined to school-aged children alone, as shown by our use of real-world, age-structured data from four diverse epidemiological settings in Côte d'Ivoire.1Lo NC Bogoch II Blackburn BG et al.Comparison of community-wide, integrated mass drug administration strategies for schistosomiasis and soil-transmitted helminthiasis: a cost-effectiveness modelling study.Lancet Glob Health. 2015; 3: e629-e638Summary Full Text Full Text PDF Scopus (79) Google Scholar Turner and colleagues miss another key message of the study: integration of mass drug administration (ie, giving albendazole with praziquantel) takes advantage of cost-efficiencies since most drugs are donated and the treatment cost is mostly for delivery. Integrated treatment should therefore almost always be considered in co-endemic settings, and integration in co-endemic settings should be considered in future studies of community-wide treatment with albendazole alone.8Brooker SJ Mwandawiro CS Halliday KE et al.Interrupting transmission of soil-transmitted helminths: a study protocol for cluster randomised trials evaluating alternative treatment strategies and delivery systems in Kenya.BMJ Open. 2015; 5: e008950Crossref Scopus (49) Google Scholar We are disappointed with the unsupported assertion that community-wide treatment will only be beneficial when elimination is reached. This outcome has not been shown in empirical studies and misses the key finding of our study: community-wide treatment is highly cost effective in many settings, even when elimination is not reached, because of the significant averted morbidity, both in children and adults.1Lo NC Bogoch II Blackburn BG et al.Comparison of community-wide, integrated mass drug administration strategies for schistosomiasis and soil-transmitted helminthiasis: a cost-effectiveness modelling study.Lancet Glob Health. 2015; 3: e629-e638Summary Full Text Full Text PDF Scopus (79) Google Scholar The ability of mass drug administration to eliminate schistosomiasis and soil-transmitted helminthiasis has not yet been satisfactorily proven, and countries will need to make funding decisions without knowing whether elimination—or just control—will be achieved. To put these efforts against one another is unproductive and not based on evidence. When infected human populations—whether preschool-aged children or adults—remain untreated, they act as a hidden reservoir and continue to drive reinfection. We have shown that expanded community-wide treatment against schistosomiasis and soil-transmitted helminthiasis addresses this hidden reservoir, decreases overall disease transmission, and is highly cost effective. Global guidelines should be re-examined to address this important finding. We declare no competing interests. Download .pdf (.18 MB) Help with pdf files Supplementary appendix Cost-effectiveness of community-wide treatment for helminthiasisNathan C Lo and colleagues (October, 2015)1 conclude that community-wide treatment programmes can be a highly cost-effective way to control morbidity of schistosomiasis and soil-transmitted helminthiasis, even in communities with low disease burden. This work is a timely contribution to an important issue; however, methodological shortcomings affect the conclusions. 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