A critical re-examination of the economics of blindness prevention under the onchocerciasis control programme

This article is a critical re-examination of the recent cost-effectiveness analysis of the Onchocerciasis Control Programme (OCP) in West Africa, undertaken by Prost and Prescott in 1984. We use the same approach, namely, measuring effectiveness of the programme by the number of healthy years of life added by the prevention of blindness. This work focuses on certain technical aspects of the data used for estimating parameter values in the cost-effectiveness calculations. Through examination of available data and the relationships between certain key variables, we estimate values that differ substantially from Prost and Prescott for the population at risk, the incidence and prevalence of onchocercal blindness, and the years of healthy life lost due to blindness. Our final results suggest that depending on the discount rate that the OCP is 7-40 times more costly as measured by discounted years of productive life added than measles immunisation. These results are in contradiction to Prost and Prescott's estimation that the OCP was more cost-effective than measles immunisation. We, however, feel that our results do not demonstrate that OCP is an inefficient use of resources. Rather, they call into question the methods used and the relevance of comparing measles immunisation and onchocerciasis control. In a subsequent article, we hope to deal directly with these conceptual problems by presenting separate humanitarian and economic cost-effectiveness measures.