Tuberculosis patients with higher levels of poverty face equal or greater costs of illness

Abstract

SETTING: Fifty-six public clinics in Limpopo Province, South Africa.OBJECTIVE: To evaluate the association between tuberculosis (TB) patient costs and poverty as measured by a multidimensional poverty index.DESIGN: We performed cross-sectional interviews of consecutive patients with TB. TB episode costs were estimated from self-reported income, travel costs, and care-seeking time. Poverty was assessed using the South African Multidimensional Poverty Index (SAMPI) deprivation score (a 12-item household-level index), with higher scores indicating greater poverty. We used multivariable linear regression to adjust for age, sex, human immunodeficiency virus status and travel time.RESULTS: Among 323 participants, 108 (33%) were 'deprived' (deprivation score >0.33). For each 0.1-unit increase in deprivation score, absolute TB episode costs were 1.11 times greater (95%CI 0.97-1.26). TB episode costs were 1.19 times greater with each quintile of higher deprivation score (95%CI 1.00-1.40), but lower by a factor of 0.54 with each quintile of lower self-reported income (higher poverty, 95%CI 0.46-0.62).CONCLUSION: Individuals experiencing multidimensional poverty and the cost of tuberculosis illness in Limpopo, South Africa faced equal or higher costs of TB than non-impoverished patients. Individuals with lower self-reported income experienced higher costs as a proportion of household income but lower absolute costs. Targeted interventions are needed to reduce the economic burden of TB on patients with multidimensional poverty.

Figure 1

Study flowchart. Of the nine TB patients excluded for missing cost data, five could not provide sufficient income information, three were unable to provide transportation costs, and one was missing both types of data. Of the 23 reference patients (i.e., those without TB) excluded for missing cost data, 15 were unable to provide sufficient income information, seven were unable to provide transportation costs and 1 was missing both types of data. TB = tuberculosis.

Figure 2

Mean costs of TB episode in US Dollars (USD) by SAMPI deprivation score and income quintile in order of decreasing poverty (defined as either decreasing SAMPI deprivation score or increasing self-reported pre-illness income). Error bars represent 95% confidence intervals. Income given as annual US Dollars. For October 2017, 1 US Dollar = 13.6 South African Rand. SAMPI = South African multidimensional poverty index

Figure 3

Absolute (panel A) and proportional (panel B) TB costs by income quintile and deprivation status. Absolute costs are given in US Dollars (1 US Dollar = 13.6 South African Rand). Sample size n is listed for each subgroup. Income was assessed at the household level prior to the onset of illness by self-report. Deprivation was defined as a SAMPI deprivation score ≥ 0.33. TB = tuberculosis; USD = US dollar; SAMPI = South African Multidimensional Poverty Index; ZAR = South African rand

Figure 4

Relative cost estimates based on different methods of time valuation for lost wages. Relative cost represents the relative change in absolute disease cost for each quintile of increasing poverty in either SAMPI deprivation score or income. The y-axis is on a log scale. Error bars represent 95% confidence intervals. “Income adjusted” denotes valuation of time as median hourly wage of the patient’s income quintile (primary analysis). “Equal income” denotes equal valuation of time for all patients using the study median as the hourly wage. “Patient estimates” denotes valuation of time based directly on patient estimates rather than an hourly wage. “No time value” refers to ignoring lost wages due to time loss and considering only out-of-pocket costs and changes to income as a result of illness. SAMPI = South African Multidimensional Poverty Index