Box 2 The unpaid time of volunteers

Community volunteers are being used within a number of other healthcare interventions: including mass drug administration, vitamin A supplementation, supporting HIV and tuberculosis patients, and community case management of childhood illnesses [24,25,26,27,28,29,30]. Voluntary labour is, by definition, free from wages to the health care provider. However, the economic value of the volunteers’ unpaid time is still important to account for, as the time they lose is a genuine economic resource that could have been used on other valuable activities (i.e. they gave up an alternative use of their time—such as paid work or leisure). There are also practical reasons why the economic costs related to volunteers’ time should be considered when evaluating different policy decisions and resource allocation. For example:

∙ Relying on volunteers for such a growing range of roles and interventions could become unsustainable. Potentially, volunteers who in the past worked for free would start expecting to be paid. Thus, ignoring the economic value associated with their time/contribution is important for accounting for the sustainability of the costs of interventions

∙ Community health volunteers are not established in every setting. Therefore, in some cases, more formal healthcare workers will be needed to perform the same tasks. Consequently, accounting for the value of the community health volunteers' unpaid contribution is an important consideration when generalizing cost data to other settings

Consequently, when performing an economic evaluation on an intervention that involves community volunteers, it is important to consider their economic cost, even when using the healthcare provider’s perspective. Despite their importance, the economic costs relating to volunteers' unpaid time are often overlooked or estimated inconsistently. This can give a misleading indication of the sustainability and replicability surrounding the costs of the interventions using community volunteers, potentially leading to inefficient policy decisions

The economic costs can be significant. For example, the economic costs related to the unpaid time contributed by community health volunteers' to mass drug administration for neglected tropical disease control have be found to be notable, with the averages of the different studies varying between US$0.05 and $0.16 per treatment [31]. For comparison a benchmark of US0.50 per treatment is commonly used for the delivery costs for such programs [32], highlighting the significance of these non-financial costs

It should be noted that at times, community health volunteers are given generous per diems and/or incentives, making the distinction between their time being paid or unpaid more difficult. In addition, some economists have argued that volunteers may be willing to supply labour for free since they perceive the benefits of volunteering to outweigh the opportunity costs associated with their time (i.e. it is of benefit to them and not a “cost”) [33]. This highlights the complexities in estimating opportunity costs