Data
We utilise data from the LSMS-ISA surveys. These are part of a global programme supported by the World Bank to undertake panel surveys and are conducted by national statistical agencies.Footnote 3 The surveys monitor population, health, and agricultural programmes in developing countries. The surveys are nationally representative and use standardised questionnaires across the different countries. As noted earlier, we use LSMS-ISA surveys from five countries, i.e. Ethiopia, Malawi, Nigeria, Tanzania, and Uganda. All five countries have at least one survey conducted during 2013–2015. The sample size is relatively large, covering more than 3200 households in each survey round. Table 2 shows the coverage of each specific survey used.
Table 2 LSMS-ISA surveys to be used in the analysis. All the LSMS-ISA are based on a two-stage cluster sampling design. In the first stage, clusters or enumeration areas (EAs) stratified according to spatial location are the principal sampling unit. The selections of EAs was based on the most recent census as the frame for each country. In the second stage, 10 households are randomly selected from each EA. Each LSMS-ISA survey is composed of at least three questionnaires: the household, agricultural, and community questionnaires. The household questionnaire covers the characteristics of the household, e.g. demographic composition and individual experience of shocks. The household questionnaires have a detailed health module capturing individual experience of illness during the past 30 days prior to the survey. Information captured in the health module includes the nature of illness, type of healthcare provider sought, and the cost of health services if paid for. In addition, the health module captures distance to healthcare provider. Furthermore, ISA surveys capture at the household level, health and medical care expenditures during the past 30 days. This serves as the major indicator of OOP expenditures used in the analysis. Finally, the ISA surveys also contain a detailed community questionnaire with a health facility survey. The facility survey captures services offered at the facility and their corresponding costs.
Estimation Approach
We utilise the framework by Wagstaff and van Doorslaer [15] who examined catastrophic health expenditures in another developing country (Vietnam). In this model, catastrophic expenditures are measured in relation to either total household expenditure or non-discretionary household expenditures (i.e. after accounting for food expenditures). For the present study, we adopt non-food expenditures as our reference for catastrophic health payments.
Healthcare expenditures are considered as catastrophic if they exceed a given threshold. This is formally represented as
$${\text{CTP}} = \frac{T}{E - F} > z,$$
(1)
where CTP is the catastrophic health expenditures, T is OOP expenditures, E is total household expenditures, F are food expenditures and Z is a set threshold. The incidence of catastrophic health expenditures can be considered within the realm of the standard Foster–Greer–Thorbecke (FGT) class of poverty indexes that incorporate the three most common poverty measures—poverty head count (P0), poverty gap (P1), and the square poverty gap (P2). If we define CTP equal 1 if \(\frac{{T_{i} }}{{E_{i} - F_{i} }} > 1\)and zero otherwise, then the head count measure is defined as
$$H = \frac{1}{N} \sum \limits_{i = 1}^{N} {\text{CTP}}_{i} .$$
(2)
The headcount does not reveal the extent to which households exceed a given threshold. To capture the extent to which household exceed the set thresholds, we measure the “catastrophic payment overshoot” and this captures the average degree by which OOP payments as share of total household non-food expenditures exceed the threshold Z. The overshoot is formally defined as
$$O_{i} = {\text{CTP}}\left[ {\left( {\frac{{T_{i} }}{{E_{i} - F_{i} }}} \right) - Z} \right],$$
(3)
where Ti represents the OOP payments of household i, Ei − Fi represents the household non-food consumption expenditure of household i, and Z represents the catastrophic threshold selected. The actual estimates of the overshoot are a simple average of the estimate in Eq. (3) defined as
$$O = \frac{1}{N} \sum \limits_{i = 1}^{N} O_{i} .$$
(4)
Following [15] as well as [16], the intensity of catastrophic expenditures is estimated as the average of the catastrophic overshoot over all households that exceed the selected catastrophic threshold. The estimated average is referred to as the mean positive overshoot. Formally, this is defined as
$${\text{MPO}} = \frac{O}{H}.$$
(16)
It is also important to understand how catastrophic payments affect different households based on the status of the welfare distribution. The distribution of the incidence and intensity of catastrophic payments is assessed by estimating concentration indices (CI) for household overshoot (Oi) and CTP. Following [15], the CIs are estimated using the covariance between the fractional rank of the household sorted by socio-economic status (consumption expenditures) and the variable of interest. If the corresponding CIs for the catastrophic payments and overshoot are labelled CE and CO respectively, they can take on values ranging from − 1 to + 1. A positive CE indicates a greater tendency for the relatively well-to-do households to exceed the selected threshold while a negative index indicates that it is mainly the worse off that exceed these payments. Similarly, a positive value for CO indicates that the overshoots are concentrated among richer households. Following Wagstaff et al. [15], in order to take into account the distribution-sensitive aspects of catastrophic payments, both the headcount and overshoot measures are adjusted by multiplying with the corresponding CI. Formally, this is written as:
$$H^{\text{W}} = H\left( {1 - C_{\text{E}} } \right), \;H_{\text{w}} \left\langle {H \;{\text{if}}\; C_{\text{e}} } \right\rangle 0$$
(6)
$$O^{\text{W}} = O(1 - C_{o} ), H_{\text{w}} \left\langle {H \;{\text{if}} \;C_{\text{o}} } \right\rangle 0$$
(7)
Variables Used in the Analysis
Household health expenditures are payments for direct healthcare services, such as medicines, consultation fees, hospital/clinic charges, laboratory diagnostic tests, as well as fees paid to traditional doctors and medicine. These expenditures are obtained from the consumption module of the survey—in particular the section on non-durable goods and frequently purchased services during the last 30 days.
Non-food household expenditures These are total household consumption expenditures less expenditures on food, i.e. housing, durable goods, health, education and transportation. This is derived from the consumption module of the LSMS surveys.
Threshold of catastrophic health expenditures In the literature, various thresholds are used to capture the severity of catastrophic health expenses—ranging from 10 [17] to 40% [16]. Following World Health Organization and World Bank [2], we adopted the 15% and 25% threshold and defined catastrophic health expenditures as health expenditures that are either 15% or 25% of a household’s ability to pay, where ability to pay is measured by non-food household expenditures.