Socioeconomic benefit to individuals of achieving 2020 targets for four neglected tropical diseases controlled/eliminated by innovative and intensified disease management: Human African trypanosomiasis, leprosy, visceral leishmaniasis, Chagas disease

Abstract

Background: The control or elimination of neglected tropical diseases (NTDs) has targets defined by the WHO for 2020, reinforced by the 2012 London Declaration. We estimated the economic impact to individuals of meeting these targets for human African trypanosomiasis, leprosy, visceral leishmaniasis and Chagas disease, NTDs controlled or eliminated by innovative and intensified disease management (IDM).

Methods: A systematic literature review identified information on productivity loss and out-of-pocket payments (OPPs) related to these NTDs, which were combined with projections of the number of people suffering from each NTD, country and year for 2011-2020 and 2021-2030. The ideal scenario in which the WHO's 2020 targets are met was compared with a counterfactual scenario that assumed the situation of 1990 stayed unaltered. Economic benefit equaled the difference between the two scenarios. Values are reported in 2005 US$, purchasing power parity-adjusted, discounted at 3% per annum from 2010. Probabilistic sensitivity analyses were used to quantify the degree of uncertainty around the base-case impact estimate.

Results: The total global productivity gained for the four IDM-NTDs was I$ 23.1 (I$ 15.9 -I$ 34.0) billion in 2011-2020 and I$ 35.9 (I$ 25.0 -I$ 51.9) billion in 2021-2030 (2.5th and 97.5th percentiles in brackets), corresponding to US$ 10.7 billion (US$ 7.4 -US$ 15.7) and US$ 16.6 billion (US$ 11.6 -US$ 24.0). Reduction in OPPs was I$ 14 billion (US$ 6.7 billion) and I$ 18 billion (US$ 10.4 billion) for the same periods.

Conclusions: We faced important limitations to our work, such as finding no OPPs for leprosy. We had to combine limited data from various sources, heterogeneous background, and of variable quality. Nevertheless, based on conservative assumptions and subsequent uncertainty analyses, we estimate that the benefits of achieving the targets are considerable. Under plausible scenarios, the economic benefits far exceed the necessary investments by endemic country governments and their development partners. Given the higher frequency of NTDs among the poorest households, these investments represent good value for money in the effort to improve well-being, distribute the world's prosperity more equitably and reduce inequity.

Fig 1. General formula for calculating productivity loss.

TPC = Total productivity costs (in US$ 2005), NTD = Neglected Tropical Disease, c = Country, y = Year, PS1 = Number of prevalent cases aged 15+ years with sequela 1, PS2 = Number of prevalent cases aged 15+ years with sequela 2, PLs1 = % productivity loss related to sequela 1 of NTD, PLs2 = % productivity loss related to sequela 2 of NTD, I = GDP per capita in the lowest quintile, D = Annual discount rate, t = Time (years beyond 2010).

Fig 2. General formula for calculating out-of-pocket payments.

TDC = Total out-of-pocket payments (in US$ 2005), NTD = Neglected tropical disease, c = Country, y = Year, PS1 = Number of persons with sequela 1 of NTD, PS2 = Number of persons with sequela 2 of NTD, DCS1 = Annual out-of-pocket payments relating to sequela 1 (per WHO region or country), DCS2 = Annual out-of-pocket payments relating to sequela 2 (per WHO region or country), PT = Percentage of patients treated, PP = Percentage of patients paying for the treatment, D = Annual discount rate, t = Time (years).

Fig 3. Productivity loss due to Chagas chronic heart disease according to the counterfactual and target achievement scenarios (millions I$—International dollars).

Total global loss per year in the counterfactual scenario (blue) and target achievement scenario (orange). The economic benefit is the difference between both scenarios.

Fig 4. Global economic benefit (productivity loss averted) for IDM NTDs, for the period 2011–2030 (billions I$—International dollars).

Global economic benefit from reaching the targets for IDM NTDs, lower and upper estimates from sensitivity analysis. Global economic benefit per disease.

Fig 5. Regional economic benefit (productivity loss averted) for IDM NTDs, for the period 2011–2030 (billions I$—International dollars) per WHO region.

Regional economic benefit from reaching the targets for IDM NTDs, for the period 2011–2030 per WHO region.

Fig 6. Global economic benefit (out-of-pocket payments averted) for IDM NTDs, for the period 2011–2030 (billions I$—International dollars).

Total economic benefit from out-of-pocket payments averted, base case estimates and 2.5th and 97.5th percentiles (billions I$—international dollars), discounting 3% from 2010.