Economic evaluation in schistosomiasis: valuation of health states preferences. A research note

Poor countries can ill-afford ineffective health care. An effective disease intervention is one which produces a net improvement in beneficiaries' quality of life and/or increases life expectancy. Unlike developed countries, very little research has been done in developing countries on the measures of the ultimate output of health care. The objectives of this study were to: (i) apply the existing health-related quality of life (HRQoL) methods in eliciting health state valuations from farmers, teachers and health professionals living and working in the schistosomiasis endemic Mwea Irrigation Scheme in Kenya; (ii) determine whether there is significant difference between average health states valuations from the three main groups of people at risk of schistosomiasis infection; and (iii) assess the relative effect of different respondent characteristics and health states prognosis on valuations. The instrument consists of seven health state descriptions-each defined along six functional dimensions: self-care, mobility, livelihood activities, energy, social participation and pain. Cardinal health state values were measured using a visual-analogue-scale (VAS). Values were elicited from three random samples of farming general public, medical professionals and teachers. The Kruskal-Wallis one-way ANOVA test showed that there is significant difference in the average health state values (for mild, moderate, severe, very severe and comatose states) obtained from the three samples. Generally, except for the valuation of the immediately following state, the other explanatory variables are not statistically significant determinants of valuations for the mild, moderate, severe and very severe states. The results suggest that VAS valuations are primarily affected by prognosis. There is urgent need for more representative and systematic HRQoL studies to test the relevance of the Western-based generic instruments in African countries contexts, with a view to developing more appropriate tool(s) if necessary.