Measuring and valuing quality of life in the economic evaluation of sanitation interventions

Abstract

Recent trials of basic sanitation interventions in low- and middle-income countries have identified little or no health impact, despite improving access to toilets and their quality. However, qualitative studies frequently report that toilet users value broader benefits for privacy, safety and status. Economic evaluations have not included these benefits, in the absence of means to measure them quantitatively, potentially leading to misallocated resources. The aim of this research was to develop and apply an approach to measuring and valuing quality of life in the economic evaluation of sanitation interventions. This is a paper-style thesis which incorporates five papers linked by short pieces of supporting material. By integrating qualitative and quantitative methods from health economics, this thesis outlines the development and application of a measure of “sanitation-related quality of life” (SanQoL). The thesis finds that the benefits of an urban sanitation intervention for toilet users’ quality of life can be quantitatively measured and valued, working alongside the Maputo Sanitation trial in Mozambique. Attributes of the measure are first identified in qualitative research using the capability approach. The validity and reliability of the ensuing SanQoL measure are assessed using psychometric analytic methods. The SanQoL measure captures the degree of achievement of five sanitation-related capabilities: privacy, safety, health, shame and disgust. Rescaling with user-derived weights results in SanQoL index values ranging from zero (no sanitation capability) to one (full sanitation capability). These index values can be used to weight sanitation-adjusted person years (SAPYs), a proposed measure of the value of sanitation. After estimating the effect of a shared, urban sanitation intervention on SanQoL, that effect is applied in a cost-effectiveness analysis using the novel SAPY measure as the outcome. This thesis demonstrates how measuring and valuing toilet users’ quality of life brings new insights to the effectiveness and cost-effectiveness of sanitation interventions.