What can dissaving tell us about catastrophic costs? Linear and logistic regression analysis of the relationship between patient costs and financial coping strategies adopted by tuberculosis patients in Bangladesh, Tanzania and Bangalore, India

Background: Tuberculosis (TB) is a major global public health problem which affects poorest individuals the worst. A high proportion of patients incur 'catastrophic costs' which have been shown to result in severe financial hardship and adverse health outcomes. Data on catastrophic cost incidence is not routinely collected, and current definitions of this indicator involve several practical and conceptual barriers to doing so. We analysed data from TB programmes in India (Bangalore), Bangladesh and Tanzania to determine whether dissaving (the sale of assets or uptake of loans) is a useful indicator of financial hardship. Methods: Data were obtained from prior studies of TB patient costs in Bangladesh (N = 96), Tanzania (N = 94) and Bangalore (N = 891). These data were analysed using logistic and linear multivariate regression to determine the association between costs (absolute and relative to income) and both the presence of dissaving and the amounts dissaved. Results: After adjusting for covariates such as age, sex and rural/urban location, we found a significant positive association between the occurrence of dissaving and total costs incurred in Tanzania and Bangalore. We further found that, for patients in Bangalore an increase in dissaving of $10 USD was associated with an increase in the cost-income ratio of 0.10 (p < 0.001). For low-income patients in Bangladesh, an increase in dissaving of $10 USD was associated with an increase in total costs of $7 USD (p < 0.001). Conclusions: Dissaving is potentially a convenient proxy for catastrophic costs that does not require usage of complex patient cost questionnaires. It also offers an informative indicator of financial hardship in its own right, and could therefore play an important role as an indicator to monitor and evaluate the impact of financial protection and service delivery interventions in reducing hardship and facilitating universal health coverage. Further research is required to understand the patterns and types of dissaving that have the strongest relationship with financial hardship and clinical outcomes in order to move toward evidence-based policy making.