PATH supports a field study to assess efficacy of household water treatment to prevent diarrheal disease

Following a successful five week pilot study, researchers at the London School of Hygiene & Tropical Medicine (LSHTM) are moving forward with a 12-month double-blinded, randomized, placebo-controlled field trial in Orissa State, India, to assess the efficacy of household water treatment to prevent diarrheal disease. The field trial will be conducted in both urban and rural settings and is designed to estimate the effect of household water treatment to prevent a disease that kills 19% of children under the age of five in developing countries (Boschi‐Pinto 2008).

While the primary objective of the study is to evaluate the efficacy of Aquatabs™ in preventing diarrhea among children under five years of age, the study will also evaluate impact on all ages, as well as weight gain in children under five, microbiological water quality, correct and consistent use, acceptability of the product for long-term use, and impact on school and work absenteeism.

A total of 2,400 children under five from an estimated 1,600 households will be enrolled in the study and, after a baseline survey, allocated into two equal-sized groups. The intervention group will receive free supplies of Aquatabs™ brand chlorine (NaDCC) tablets together with instructions on use; the control group will receive a placebo and the same instructions. Population Services International (PSI), a social-marketing agency with decades of experience promoting household water treatment solutions in 21 countries in Africa and Asia, will be hosting the trial and providing ongoing promotion and interpersonal communication support to study participants.

Why household water treatment?

An estimated 884 billion people lack access to safe water. The problem is particularly acute among rural and urban slum populations, many of which suffer from increased exposure due to poor sanitation. Storing water in the home—a common practice due to distant or unreliable water supplies—is also a source of diarrheagenic pathogens (Wright 2003). As a result, WHO has encouraged the development and use of improved point-of-use water treatment at the household level (WHO 2007, 2008). Despite the uncertainty over the actual estimate of effect, these interventions have been shown to be an overall effective and cost-effective means of preventing diarrheal and other waterborne diseases (Fewtrell 2005; Clasen 2006, 2007).

With nearly 400,000 deaths of children each year from diarrheal diseases—more than twice that of any other country—India alone accounts more than 20% of the worldwide mortality associated with diarrhea (UNICEF 2009).

Why a field study to address health impact?

Donors, policymakers, and many implementers rely on evidence for their decision-making. While dozens of studies have been undertaken to assess the impact of household water treatment interventions on diarrhea, most follow an open trial design in which subjects are aware of their allocation to the intervention and control groups—a potential source of bias, particularly with a subjective outcome such as reported diarrhea. Few such studies have attempted to blind participants by using a placebo, and except for one study in North America (Colford 2009), none of these placebo-controlled studies have reported a statistically meaningful reduction in diarrheal disease among the intervention groups. Unfortunately, each of these studies was conducted under circumstances that raised questions about its results (Clasen 2006). In the most recent example, a 2006 study in Ghana (Jain 2010) compared an intervention group that received chlorine tablets plus a safe storage vessel with a control group that received the vessel with placebo tablets. It is well-established that safe storage vessels alone prevent household contamination of drinking water (Wright 2003). Investigators hypothesized that providing control households with the vessel minimized the additional contribution of the tablets alone. While the tablets were shown to significantly improved water quality, diarrheal rates were lower than expected for both groups. As a result, investigators reported that the study may not have had sufficient statistical power to detect a difference in diarrhea incidence between the two groups.

To minimize similar problems, LSHTM investigators designed the Orissa study as a simple comparison of chlorine tablets against no intervention. They will also measure differences in weight-for-age Z-scores among children, an objective outcome not subject to reporting bias that LSHTM investigators have shown to be proxy for acute diarrhea (Schmidt 2010). They also conducted a 5-week pilot study to test water quality, data collection tools, confirm the suitability of the area, explore use and acceptability of the tablets among the target population (e.g. dosage, acceptability of taste etc.), and evaluate the effectiveness of blinding. The pilot provided sufficient evidence of uptake of the intervention and brought some important issues to light.

Study collaborators

This study will be conducted by representatives of LSHTM, a leader in research concerning water, sanitation, and hygiene interventions in low-income settings. Thomas F. Clasen, JD, PhD, a senior lecturer at LSHTM, is the principal investigator for the study. The host organization for the study is PSI, a US-based nongovernmental organization with offices in New Delhi and extensive operations in India.

PATH is contributing to the study as part of its Safe Water Project, a 5-year learning grant supported by the Bill & Melinda Gates Foundation to investigate options for scaling up household water treatment products. Additional financial and other support is being provided by the United States Agency for International Development, Medentech, Ltd. (the manufacturer of Aquatabs™) and the American Chemistry Council. Neither PSI nor any of the other financial supporters for the trial will play any role in the collection or analysis of the data or in the preparation of the reports or papers presenting the results of the study.

References

Boschi-Pinto C, Velebit L, Shibuya K. Estimating child mortality due to diarrhea in developing countries. Bulletin of the World Health Organization. 2008; 86(9): 710–717.

Clasen T, Haller L, Walker D, et al. Cost-effectiveness analysis of water quality interventions for preventing diarrheal disease in developing countries. Journal of Water and Health. 2007; 5(4):599–608.

Clasen T, Roberts I, Rabie T, et al. Interventions to improve water quality for preventing diarrhoea (Cochrane Review). British Medical Journal. 2007; 334(7597):755–756.

Colford J, Hilton J, Wright C, et al. The Sonoma water evaluation trial: a randomized drinking water intervention trial to reduce gastrointestinal illness in older adults. American Journal of Public Health. 2009; 99(11):1988–95.

Fewtrell L, Kaufmann R, Kay D, et al. Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis. The Lancet Infectious Diseases. 2005; 5:42–52.

Jain S, Sahanoon O, Blanton E, et al. Sodium Dichloroisocyanurate Tablets for Routine Treatment of Household Drinking Water in Peri-urban Ghana: A Randomized Controlled Trial. American Journal of Tropical Medicine and Hygiene. 2006; 82(1):16–22.

Schmidt W, Boisson S, Genser B. Weight-for-age z-score as a proxy marker for diarrhoea in epidemiological studies. Journal of Epidemiology & Community Health. 2010; 64(12):1074-9.

United Nations Children’s Fund (UNICEF). Diarrhea: why children are still dying and what can be done. UNICEF/WHO. New York: United Nations Children’s Fund; 2009.

World Health Organization (WHO). Combating waterborne disease at the household level. Geneva: World Health Organization; 2007.

World Health Organization (WHO). Guidelines for Drinking Water Quality. Geneva: World Health Organization; 2006.

Wright J, Gundry S, Conroy. Household drinking water in developing countries: a systematic review of microbiological contamination between source and point-of-use. Tropical Medicine & International Health. 2006; 9(1):106–17.