Study objective: To review the World Health Organisation's methodological approach for the purpose of measuring health inequalities presented in the WHR 2000 and reference papers.
Main findings: Recommending that health inequalities be assessed by measuring interindividual differences, without regard for the distribution of health status among specific population subgroups, the approach taken by WHO does not take into account the socioeconomic dimension, is strongly influenced by the extent of socioeconomic inequalities in the population, and suffers from the health redistribution problem. Apart from the conceptual issues, the estimation procedure also has methodological problems hidden in a sophisticated statistical procedure, which is confusingly explained in one of the referred discussion papers. The results presented in the WHR 2000 are based on Demographic and Health Survey data that refer to more than 10 years ago.
Other methodological problems: The WHO's individual differences measure of health inequalities is expressed in units of survival time raised to the power of 2.5. Besides the difficulty of interpretation, the individual differences index is not a relative measure. However, the index of equality of child survival was defined as the complement of the individual differences index, as though it were a relative measure.
Neglect to the specialised literature: The WHO's index is a particular case in a family of measures that provides generalisations of the Gini coefficient. However, concerns on the adequacy and validity of this procedure for the purposes of measuring health inequalities were completely ignored.
Conclusions: The need to open up the debate with the scientific community has been recently recognised by the executive board of the WHO. In view of the new prospect, the paper concludes by raising some points that can contribute to the discussion on the measurement of health inequalities, with regard to the evaluation of the health system performance.