Cost-effectiveness of community-wide treatment for helminthiasis
Authors: Hugo C Turner, James E Truscott, Roy M Anderson
Journal: The Lancet Global Health (2016)

Nathan C Lo and colleagues (October, 2015)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 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. Within the model, the health burden of schistosomiasis over time was estimated by simply assigning a disability-adjusted life-year (DALY) weight to the prevalence of infection, as in a cross-sectional Global Burden of Disease study. This estimation corresponded to more than 92% of the projected disease burden averted within the study (measured in DALY). However, this approach will probably significantly overestimate the effect and hence the cost-effectiveness of community-wide treatment because it does not differentiate between prevention of heavy and light infections (the former being associated with morbidity)—this could be avoided by estimating burden on the basis of intensity of infection.2Chan MS Guyatt HL Bundy DA Medley GF Dynamic models of schistosomiasis morbidity.Am J Trop Med Hyg. 1996; 55: 52-62PubMed Google Scholar The effect of mass drug administration on transmission also depends on the relation between worm burden and egg production (which declines as burden increases). This relation has been shown to vary between species3Anderson RM May RM Helminth infections of humans: mathematical models, population dynamics, and control.Adv Parasitol. 1985; 24: 1-101Crossref PubMed Scopus (459) Google Scholar and affects assumptions with respect to the underlying burden and the effectiveness of control. By assuming that the relation is the same across species, Lo and colleagues run the risk of overestimating the effect of community-wide treatment for some species. Community-wide treatment can be a powerful intervention against soil-transmitted helminthiasis and schistosomiasis, but the effect is highly dependent on the epidemiological setting.4Anderson RM Truscott JE Hollingsworth TD The coverage and frequency of mass drug administration required to eliminate persistent transmission of soil-transmitted helminths.Philos Trans R Soc Lond B Biol Sci. 2014; 369: 20130435Crossref PubMed Scopus (125) Google Scholar, 5Anderson RM Turner HC Truscott JE Hollingsworth TD Brooker SJ Should the goal for the treatment of soil transmitted helminth (STH) infections be changed from morbidity control in children to community-wide transmission elimination?.PLoS Negl Trop Dis. 2015; 9: e0003897Google Scholar For example, although community-wide treatment is probably essential to fully control hookworm's morbidity, it might not be needed in regions that are dominated by Ascaris lumbricoides or Trichuris trichiura.4Anderson RM Truscott JE Hollingsworth TD The coverage and frequency of mass drug administration required to eliminate persistent transmission of soil-transmitted helminths.Philos Trans R Soc Lond B Biol Sci. 2014; 369: 20130435Crossref PubMed Scopus (125) Google Scholar, 5Anderson RM Turner HC Truscott JE Hollingsworth TD Brooker SJ Should the goal for the treatment of soil transmitted helminth (STH) infections be changed from morbidity control in children to community-wide transmission elimination?.PLoS Negl Trop Dis. 2015; 9: e0003897Google Scholar Community-wide treatment to control morbidity could cost-effective in some settings, but the investigators might have overestimated its cost-effectiveness, particularly in areas with a low disease burden. Because of obvious programmatic and financial constraints, the implementation of community-wide treatment will not be possible in every location in which these diseases are endemic. A large change in policy will necessitate analysis of a range of approaches and epidemiological settings. The benefit in many areas will not lie in morbidity control but in the capacity to accelerate progress to elimination, thereby reducing the programme's duration (which is potentially cost saving).5Anderson RM Turner HC Truscott JE Hollingsworth TD Brooker SJ Should the goal for the treatment of soil transmitted helminth (STH) infections be changed from morbidity control in children to community-wide transmission elimination?.PLoS Negl Trop Dis. 2015; 9: e0003897Google Scholar, 6Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RM. Cost-effectiveness of scaling up mass drug administration for the control of soil-transmitted helminths: a comparison of cost function and constant costs analyses. Lancet Infect Dis (in press).Google Scholar, 7Turner HC Truscott JE Hollingsworth TD Bettis AA Brooker SJ Anderson RM Cost and cost-effectiveness of soil-transmitted helminth treatment programmes: systematic review and research needs.Parasit Vectors. 2015; 8: 355Crossref Scopus (45) Google Scholar Ultimately, whether community-wide treatment is appropriate or not will depend on the epidemiological setting and whether the goal is to control morbidity or break transmission. We declare no competing interests. RMA is a Non-Executive Director of GlaxoSmithKline. Cost-effectiveness of community-wide treatment for helminthiasis – Authors' replyWe are delighted by the interest in our study of the cost-effectiveness of expanded community-wide treatment against schistosomiasis and soil-transmitted helminthiasis.1 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,2 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. Full-Text PDF Open Access