The role of modelling to inform context-specific anaemia programming
Authors: Reina Engle-Stone
Journal: The Lancet Global Health (2020)

Despite longstanding recognition of anaemia as a global health problem, anaemia prevalence among children aged 6–59 months only decreased from 47% to 43% between 1995 and 2011.1Stevens G Finucane M De-Regil L et al.Global, regional, and national trends in haemoglobin concentration and prevalence of total and severe anaemia in children and pregnant and non-pregnant women for 1995–2011: a systematic analysis of population-representative data.Lancet Glob Health. 2013; 1: e16-e25Summary Full Text Full Text PDF PubMed Scopus (814) Google Scholar Although the causes of anaemia are multifactorial, interventions have largely focused on delivery of iron. However, increasing recognition has been given to the potential harms of providing iron in contexts where children are at high risk of malaria and diarrhoea.2Prentice AM Mendoza Y Pereira D et al.Dietary strategies for improving iron status: Balancing safety and efficacy.Nutr Rev. 2017; 75: 49-60Crossref PubMed Scopus (64) Google Scholar Everywhere, programmatic decisions need to balance benefits, risks, and costs of interventions, often in the absence of comprehensive information about all three. Modelling tools can help guide these decisions.3Engle-Stone R Vosti SA Luo H et al.Weighing the risks of high intakes of selected micronutrients compared with the risks of deficiencies.Ann N Y Acad Sci. 2019; 1446: 81-101Crossref PubMed Scopus (6) Google Scholar Micronutrient powders (MNPs) are recommended by WHO to improve iron status and reduce anaemia among children4WHOWHO guideline: use of multiple micronutrient powders for point-of-use fortification of foods consumed by infants and young children aged 6–23 months and children aged 2–12 years. World Health Organization, Geneva2016Google Scholar and are now distributed in dozens of countries, but they have been subject to debate about their benefits and risks. In The Lancet Global Health, Sant-Rayn Pasricha and colleagues5Pasricha S-R Gheorghe A Sakr-Ashour F et al.Net benefit and cost-effectiveness of universal iron-containing multiple micronutrient powders for young children in 78 countries: a microsimulation study.Lancet Glob Health. 2020; 8: e1071-e1080Summary Full Text Full Text PDF PubMed Scopus (4) Google Scholar present a quantitative model to estimate net benefits (as disability-adjusted life-years [DALYs] averted) and cost-effectiveness of MNP programmes for young children. The authors developed a microsimulation model to estimate net country-specific DALYs, years lived with disability (YLDs), and years of life lost (YLLs) due to anaemia, malaria, and diarrhoea that were averted (or increased) by provision of a 6-month course of MNPs to children aged 6 months in 78 countries, compared with no intervention. Additionally, they modelled programme and health-care costs to determine cost per DALY averted. Assuming 100% coverage, the MNP intervention yielded a net benefit in DALYs averted in 54 countries (24 in Africa, 19 in Asia and the Middle East, 11 in Latin America) and net harm in 24 countries (22 in Africa, one in Asia, and one in Latin America). Pasricha and colleagues' results identify countries in which MNP distribution might yield the greatest benefit in DALYs and suggests the sobering conclusion that programmes in some countries might yield net harms. The analysis highlights areas of research needed and provides context-specific predictions to inform difficult and expensive policy decisions. Model utility depends on the quality of input data, plausibility of assumptions, and a balanced interpretation of the results. Information gaps are inevitable, but model construction exposes gaps in knowledge, some of which could be filled by additional research. The implications of uncertainty in input parameters such as disease burden, intervention coverage, and programme costs can be addressed largely by sensitivity analyses. For example, the model by Pasricha and colleagues indicated that low coverage of MNP interventions, which plagues many programmes, would reduce cost-effectiveness,5Pasricha S-R Gheorghe A Sakr-Ashour F et al.Net benefit and cost-effectiveness of universal iron-containing multiple micronutrient powders for young children in 78 countries: a microsimulation study.Lancet Glob Health. 2020; 8: e1071-e1080Summary Full Text Full Text PDF PubMed Scopus (4) Google Scholar and the same could be inferred for low adherence. Reliance on effect sizes from systematic reviews strengthens the analysis, although knowledge about potential harms remains limited. Although increased diarrhoea and adverse gut health effects have been observed among children consuming iron-containing MNPs, the overall effect size on diarrhoea in the updated Cochrane review was non-significant (relative risk 1·09, 95% CI 0·80–1·47).5Pasricha S-R Gheorghe A Sakr-Ashour F et al.Net benefit and cost-effectiveness of universal iron-containing multiple micronutrient powders for young children in 78 countries: a microsimulation study.Lancet Glob Health. 2020; 8: e1071-e1080Summary Full Text Full Text PDF PubMed Scopus (4) Google Scholar Lower iron doses and novel formulations of MNPs might reduce adverse gastrointestinal effects.6Paganini D Zimmermann MB The effects of iron fortification and supplementation on the gut microbiome and diarrhea in infants and children: a review.Am J Clin Nutr. 2017; 106: 1688S-1693SCrossref PubMed Scopus (85) Google Scholar Understanding the incidence and severity of adverse effects with different versions of MNPs, as well as modification of these relationships by individual or environmental characteristics including exposure to infectious diseases and related control programmes, are urgent research needs. A fundamental modelling decision is the selection of the primary outcome. DALYs are useful as an aggregate measure that permits direct comparisons of disparate health conditions, but disability weights are subjective and do not exist for all conditions of interest. For example, increases in status of iron and other nutrients have benefits beyond those that are captured by DALYs for anaemia, and MNP distribution programmes could improve child feeding practices more generally.7Siekmans K Bégin F Situma R Kupka R The potential role of micronutrient powders to improve complementary feeding practices.Matern Child Nutr. 2017; e12464Crossref Scopus (16) Google Scholar Incorporation of these effects into the net benefits of MNPs would require translation into harmonised units for comparison with other interventions. By contrast with previous studies,8Sharieff W Zlotkin S Ungar WJ Feldman B Krahn MD Tomlinson G Economics of preventing premature mortality and impaired cognitive development in children through home-fortification: a health policy perspective.Int J Technol Assess Health Care. 2008; 24: 303-311Crossref PubMed Scopus (5) Google Scholar Pasricha and colleagues did not find sufficient evidence to model effects of MNPs on cognition or future earning potential. Accounting for the benefits of anaemia reduction alone, the cost-effectiveness of MNPs was modest compared with that of other interventions,9Horton S Levin C Cost-effectiveness of interventions for reproductive, maternal, neonatal, and child health.in: Black R Laxminarayan R Temmerman M Reproductive, maternal, newborn, and child health: disease control priorities. third edn. The International Bank for Reconstruction and development, The World Bank, Washington, DC2016Crossref Google Scholar even in optimistic scenarios (ranging from median $1741 [IQR 1392–2186] in Africa to $3038 [2339–3801] in Latin America, without modelling harms). Decision makers should carefully weigh this information in light of country priorities, and the alternative interventions and resources available. Future work might include updating model calculations as new evidence becomes available and exploring alternative outcome measures. Modelling challenges aside, Pasricha and colleagues' results underscore that context matters. The selection of effective interventions requires characterisation of causes of anaemia, particularly the relative contributions of iron and infections such as malaria. The country-specific modelling reports might spark constructive dialogue on the role of MNPs in national nutrition strategies and the integration of these efforts with infection control. For large or diverse countries, extending this approach to examine subnational variation in anaemia burden and causes and programme reach and costs might provide insights into programme targeting. These results are consistent with WHO guidance to provide iron-containing interventions only where measures to prevent and treat malaria are in place4WHOWHO guideline: use of multiple micronutrient powders for point-of-use fortification of foods consumed by infants and young children aged 6–23 months and children aged 2–12 years. World Health Organization, Geneva2016Google Scholar and Home Fortification Technical Advisory Group recommendations to coordinate with malaria control programmes before initiating MNP distribution.10Home Fortification Technical Advisory GroupTechnical brief on the use of home fortification with micronutrient powders containing iron in malaria endemic regions. Home Fortification Technical Advisory Group, Geneva2018Google Scholar Strengthening infectious disease control programmes is a necessary priority and a strategy for anaemia reduction; this will also shift benefit-risk calculations for iron-containing interventions such as MNPs. The serious consequences of early-life malnutrition demand action in the face of uncertainty; decisions should be re-evaluated as new evidence becomes available. Although the evidence base is usually intervention-based, a problem-driven approach lays the groundwork to identify the most beneficial and cost-effective portfolio of interventions to pursue. To address anaemia, discussions should begin with an understanding of the causes, which will probably vary by country and region. Information gaps remain, including research on intervention benefits and risks, and up-to-date global data on nutritional status, disease burden, and programme implementation and costs. Efforts to close these gaps are underway, and periodic modelling exercises can help identify key research needs and inform decisions in the meantime. Modelling results, such as those presented by Pasricha and colleagues, provide new information to enrich ongoing discussions on strategic use of available resources to address childhood anaemia and other pressing global health challenges. RE-S reports research grants from the Global Alliance for Improved Nutrition, Helen Keller International, Sight and Life Foundation, and the Bill & Melinda Gates Foundation; and travel support from UNICEF. Net benefit and cost-effectiveness of universal iron-containing multiple micronutrient powders for young children in 78 countries: a microsimulation studyNet health benefits of MNPs vary between countries, are highest where prevalence of moderate and severe anaemia is greatest but infection prevalence is smallest, and are ameliorated when coverage of the intervention is poor. Our data provide country-specific guidance to national policy makers. Full-Text PDF Open Access