The health and economic benefits of the global programme to eliminate lymphatic filariasis (2000-2014)

Abstract

Background: Lymphatic filariasis (LF), also known as elephantiasis, is a neglected tropical disease (NTD) targeted for elimination through a Global Programme to Eliminate LF (GPELF). Between 2000 and 2014, the GPELF has delivered 5.6 billion treatments to over 763 million people. Updating the estimated health and economic benefits of this significant achievement is important in justifying the resources and investment needed for eliminating LF.

Method: We combined previously established models to estimate the number of clinical manifestations and disability-adjusted life years (DALYs) averted from three benefit cohorts (those protected from acquiring infection, those with subclinical morbidity prevented from progressing and those with clinical disease alleviated). The economic savings associated with this disease prevention was then analysed in the context of prevented medical expenses incurred by LF clinical patients, potential income loss through lost-labour, and prevented costs to the health system to care for affected individuals. The indirect cost estimates were calculated using the human capital approach. A combination of four wage sources was used to estimate the fair market value of time for an agricultural worker with LF infection (to ensure a conservative estimate, the lowest wage value was used).

Results: We projected that due to the first 15 years of the GPELF 36 million clinical cases and 175 (116-250) million DALYs will potentially be averted. It was estimated that due to this notable health impact, US$100.5 billion will potentially be saved over the lifetimes of the benefit cohorts. This total amount results from summing the medical expenses incurred by LF patients (US$3 billion), potential income loss (US$94 billion), and costs to the health system (US$3.5 billion) that were projected to be prevented. The results were subjected to sensitivity analysis and were most sensitive to the assumed percentage of work hours lost for those suffering from chronic disease (changing the total economic benefit between US$69.30-150.7 billion).

Conclusions: Despite the limitations of any such analysis, this study identifies substantial health and economic benefits that have resulted from the first 15 years of the GPELF, and it highlights the value and importance of continued investment in the GPELF.

Keywords: DALYs averted; Economic impact; GPELF; Health impact; Lymphatic filariasis; Programme evaluation.

Fig. 1

The number of countries that have started a LF MDA programme (a) and the cumulative number of treatments (b) provided by the GPELF over time. Data from the PCT databank [5]. Values in black indicate data provided after the timeframe of the previous analyses (2000–2007) [2, 4]. Insert in panel b illustrates the proportion of the cumulative number of treatments (2000–2014) in each of the different WHO regions (AMRO Region of the Americas, AFRO African Region, EMRO Eastern Mediterranean Region, WPRO Western Pacific Region, SEARO South-East Asia Region)

Fig. 2

Baseline model assumptions. Assumptions based on [2, 4]. The sources for the parameters are outlined in Table 3

Fig. 3

Schematic representation of the benefit cohorts and the assumed impact of treatment. *The number of uniquely treated individuals in any one country was assumed to be the maximum number of individuals treated in any single MDA for each country

Fig. 4

The estimated decline in the number of people at-risk of LF infection over time. The reductions were projected using the model presented in [18] and Fig. 3. Since a few countries are still doing mapping/have not started, the numbers at-risk remain incompletely defined. If a country has passed the Transmission Assessment Survey (TAS) in all of its implementation units it was assumed to have an at-risk population of zero (from that point forward)

Fig. 5

Duration of the health and economic benefits for the different benefit cohorts. The base year of the analysis was 2014. Health and economic benefits are calculated only for the benefit cohort populations receiving MDA between 2000 and 2014 (red bar); however, the benefits are gained until the end of their lifetime (green bar). For modelling purposes, single average ages were used to encompass the entire age range of individuals in each population benefit cohort accounting for the fact that, in reality, some individuals receiving treatment will be younger or older than the average age. The size of each benefit cohort decreases each year based on country and age-specific mortality rate. Figure based on [4]

Fig. 6

Total economic benefit disaggregated cost type

Fig. 7

Total Economic benefits by morbidity type, and clinical presentation

Fig. 8

Tornado plot illustrating the impact of the sensitivity analysis on the estimated total economic benefit of the GPELF (2000–2014). The parameter ranges investigated are shown in Table 7. Results stratified by cost type are shown in Additional file 2: Table S6