Returns on investment can be assessed in monetary terms using cost-benefit analysis (CBA), or in terms of disease cases or deaths averted using cost-effectiveness analysis (CEA).

The economic benefits of hygiene

There are three main ways in which practicing hygiene behaviour can have economic benefits. The first is in provision of direct health gains, such as avoided deaths and avoided cases of diseases (e.g. COVID-19). Systematic reviews have identified that handwashing with soap can result in a reduction in diarrhoeal disease by about 30% and a reduction in acute respiratory infections by about 21%. Various studies are also able to quantify the ‘cost of illness’, such as for diarrhoea. Second, there can be indirect health benefits, such as the value of time lost if a person is sick or caring for a person who is sick. Third, there is economic value in improving quality of life, through feelings of dignity, pride, or cleanliness, though these have not been quantified in existing literature. While relatively little evidence exists on the relationship between COVID-19 and handwashing and its effects, several studies explore how hand hygiene can limit influenza transmission and seasonal coronavirus in various contexts.

Cost-benefit studies of hygiene programmes

There are few CBA and CEA studies for hygiene programmes, relative to those that exist for drinking water or sanitation programmes. In particular, there are no such studies in humanitarian settings, despite ‘hygiene kits’ and associated hygiene promotion often being at the top of the list for interventions in such settings. It is plausible that returns on hygiene investments in humanitarian settings might be higher in the short-term than interventions in stable settings, due to heightened disease risk and vulnerability. However, any impacts are also likely to be less sustained, and intervention costs may be higher in crisis settings. Studies in this area are required.

One high-quality cost-benefit study which synthesises evidence on the effectiveness of interventions and their costs across settings applied a hypothetical model developed for a typical low-income country setting. This is a particularly useful study because the authors incorporate both rates of uptake (the proportion of people targeted by a programme who change their behaviour) and of subsequent adherence (the proportion of people who changed their behaviour who continue to practice the new behaviour). Their model has different scenarios for ‘low’, ‘medium’ and ‘high’ performance on these two factors to account for real-world variation. They simulate different hygiene programme scenarios where 20-60% of the target population initially take up the new behaviour (rate of uptake), and of that population, 20-80% continue to practice it over the duration of the intervention (subsequent adherence). Under the authors’ ‘medium’ scenario for uptake and adherence, results from 10,000 simulations of the model show a base case benefit-cost ratio of 2.1 (a return on investment of about $2 for $1 invested). The benefit-cost ratio was greater than 1 in 80% of their simulations. The scenario with higher uptake and adherence suggests a return of $6 for $1 invested, and for lower uptake/adherence a return of only $0.9. It is important to emphasise that this is a hypothetical study, with data collated from review of many studies. There is a serious lack of cost-benefit studies of real-world handwashing interventions, based on empirical evidence on what actually happened in a given setting. Benefit-cost ratios may also be higher if studies included health benefits beyond diarrhoea, such as for acute respiratory infections, which this study did not do.

It would be beneficial to future hygiene decision-making if implementers filled this gap in evidence by conducting cost-benefit analyses of hygiene programmes, and particularly by collecting the required data during design and implementation. Advocacy targeting implementers who design and implement hygiene programmes, as well as donors who fund such studies, would help to advance understanding of hygiene programming costs and benefits, and guide design of more effective and economically-beneficial programs.

Cost-effectiveness studies of hygiene programmes

A high-quality cost-effectiveness study of an empirical intervention in Burkina Faso evaluated a handwashing promotion intervention in terms of its uptake and behaviour change among mothers of young children. Combining these estimates with secondary data on health risk reduction, the authors concluded that the intervention cost USD 51 per case of diarrhoea averted, compared to no intervention. Such results are hard to interpret alone. The Disease Control Priorities (DCP) project synthesises results from individual cost-effectiveness studies into combined assessments of the cost-effectiveness of health interventions, standardised according to the disability-adjusted life years (DALYs) averted benefit metric. Based on the above CEA study, DCP authors estimated a range for handwashing cost-effectiveness of USD 90–225 per DALY averted (2012 prices). Their graph below, which compares the relative cost-effectiveness of various child health interventions, identifies handwashing as a highly cost-effective intervention and on a similar level to oral rehydration therapy and most childhood vaccinations.

Regarding what is known about the return on investment in hygiene programming, four messages are to be emphasised:

Want to learn more about the economics of hygiene programmes?

Author: Ian Ross
Review: Marc Jeuland, Guy Hutton, Robin Lloyd
Last Update: 15.12.2020