Tag Archives: Global Burden of Disease

Estimates on the WASH-related Global Burden of Disease

Below are abstracts and links to the full-text of articles in the August 2014 issue of  Tropical Medicine and International Healthtmih

Focus on the Global Burden of Disease from Water
While the methods of Global Burden of Disease (GBD) study continue to evolve, recent changes raise questions about the basis of new estimates of the risk associated with water, sanitation and hygiene and warrant consideration of alternative approaches.

  • ​Inadequate water, sanitation and hygiene are estimated to have caused 842,000 deaths from diarrhoea in 2012, i.e., 1.5% of deaths worldwide. These include 361,000 deaths of children under five years.
  • ​A systematic review of the global prevalence of handwashing with soap and its effect on diarrhoeal diseases estimates that only 19% of the world’s population washes hands with soap after contact with excreta and that handwashing reduces the risk of diarrhoeal disease by 23%–40%.
  • ​Based on over 300 studies from a systematic review, an estimated 1.1 billion people are exposed to a drinking water source of moderate to high risk.
  • ​A meta-regression shows that risks of diarrhoea from inadequate drinking water and sanitation could be reduced considerably through targeted interventions. Risk differences depend on type of intervention.

1 – Authors:  Clasen, Thomas, Pruss-Ustun, Annette, Mathers, Colin D., et al.

TI  - Estimating the impact of unsafe water, sanitation and hygiene on the global burden of disease: evolving and alternative methods
Abstract – http://onlinelibrary.wiley.com/doi/10.1111/tmi.12330/abstract
AB  – The 2010 global burden of disease (GBD) study represents the latest effort to estimate the global burden of disease and injuries and the associated risk factors. Like previous GBD studies, this latest iteration reflects a continuing evolution in methods, scope and evidence base. Since the first GBD Study in 1990, the burden of diarrhoeal disease and the burden attributable to inadequate water and sanitation have fallen dramatically. While this is consistent with trends in communicable disease and child mortality, the change in attributable risk is also due to new interpretations of the epidemiological evidence from studies of interventions to improve water quality. To provide context for a series of companion papers proposing alternative assumptions and methods concerning the disease burden and risks from inadequate water, sanitation and hygiene, we summarise evolving methods over previous GBD studies. We also describe an alternative approach using population intervention modelling. We conclude by emphasising the important role of GBD studies and the need to ensure that policy on interventions such as water and sanitation be grounded on methods that are transparent, peer-reviewed and widely accepted.

2 – Authors: Prüss-Ustün, Annette, Bartram, Jamie, Clasen, Thomas,  et al.

TI  – Burden of disease from inadequate water, sanitation and hygiene in low- and middle-income settings: a retrospective analysis of data from 145 countries

Objective – To estimate the burden of diarrhoeal diseases from exposure to inadequate water, sanitation and hand hygiene in low- and middle-income settings and provide an overview of the impact on other diseases.

Methods – For estimating the impact of water, sanitation and hygiene on diarrhoea, we selected exposure levels with both sufficient global exposure data and a matching exposure-risk relationship. Global exposure data were estimated for the year 2012, and risk estimates were taken from the most recent systematic analyses. We estimated attributable deaths and disability-adjusted life years (DALYs) by country, age and sex for inadequate water, sanitation and hand hygiene separately, and as a cluster of risk factors. Uncertainty estimates were computed on the basis of uncertainty surrounding exposure estimates and relative risks.

Results – In 2012, 502 000 diarrhoea deaths were estimated to be caused by inadequate drinking water and 280 000 deaths by inadequate sanitation. The most likely estimate of disease burden from inadequate hand hygiene amounts to 297 000 deaths. In total, 842 000 diarrhoea deaths are estimated to be caused by this cluster of risk factors, which amounts to 1.5% of the total disease burden and 58% of diarrhoeal diseases. In children under 5 years old, 361 000 deaths could be prevented, representing 5.5% of deaths in that age group.
Conclusions – This estimate confirms the importance of improving water and sanitation in low- and middle-income settings for the prevention of diarrhoeal disease burden. It also underscores the need for better data on exposure and risk reductions that can be achieved with provision of reliable piped water, community sewage with treatment and hand hygiene.

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Editorial – The elusive effect of water and sanitation on the global burden of disease

Editorial – The elusive effect of water and sanitation on the global burden of disease. Tropical Medicine and  International Health, Feb 2014.

by  Wolf-Peter Schmidt, Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK. Tel.: +44-20-7636 8636, E-mail: Wolf-Peter.Schmidt@lshtm.ac.uk

About 2.5 billion people lack access to improved sanitation, and 1 billion have no access to any form of sanitation (UNICEF 2013). About 780 million people lack access to an improved water source, a figure that is based on a fairly generous definition incorporating little with respect to reliability, proximity and convenience of access (UNICEF 2013).

While the ancient Romans may already have been aware of it (Bradley 2012), water and sanitation came to be regarded as key to improve health in the growing cities of Europe and America in the late 19th and early 20th centuries. A number of notable observational studies were carried out that even with the limited epidemiological tools available at the time all but proved the direct link between water, sanitation and health (Snow 1860; Pringle 1910). By contrast, in the early days of development aid in the post-colonial era, water and sanitation were often not regarded as a health issue, but primarily provided with the aim of making people’s life easier and enable developmental activities. Whoever tried to argue for more investment on health grounds was faced by a lack of epidemiological studies conducted in low-income settings, which led to a renewed interest in research from the 1970s.

Simple before/after and case-control studies to evaluate water and sanitation programmes
The studies on water and sanitation conducted in low-income settings since the 1970s were usually simple in design (Rubenstein et al.1969; Aziz et al1990; Zhang et al20002005; Azurin & Alvero 2007). Typically, a programme to improve water access would be implemented in one or two villages, with latrine construction and some form of hygiene education being provided at the same time. Disease (for example diarrhoea, schistosomiasis or soil-transmitted helminths) would be measured at baseline and then again after the intervention. A couple of not too distant villages with ‘similar socio-economic conditions’ would have been followed up as a control group. Allocation of the intervention was unlikely to be random. Villages might have received the intervention because they had many diseases or were the poorest in the region. They might have been chosen for having been the least or the most accessible, the politically most influential or the most neglected. The commonly small number of allocated villages enabled a close supervision of the intervention, assuring that everything was carried out according to plan. However, the within-village (‘-cluster’) correlation of disease meant that statistically not much could be made of any difference between intervention and control arm if there were <5 or 6 villages on either side. Accounting for the baseline levels of disease allowed strengthening the causal inference (Norman & Schmidt 2011), but only to some extent. Larger, randomised studies were deemed unfeasible given the logistical and engineering complexities involved, and the low budgets available at the time.

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