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associated with each disease as a single number.* The system that evolved, described in Chapter 4, consolidates information on the annual numbers of illness episodes and their durations, with additional data on related complications, sequelae, and deaths. (For chronic disability, the system incorporates the annual increment to the pool of individuals affected.) It also incorporates value judgments on the undesirability (disutility) of various conditions occurring in various age groups.

Disease Burden Estimates

Whenever possible, global or regional information from the World Health Organization or other knowledgeable sources was used as the starting point for the disease burden estimates needed in this analysis. For many conditions, however, information needed to estimate disease burdens was not available or was not of the desired reliability; in these cases, calculations were based on judgments and assumptions made by committee members and staff with the aid of consultants. Table 1.2 presents an example of the format used to consolidate disease burden information.

Infant Mortality Equivalence Values

An important feature of the system is that it allows the user to change the perspective on disutility of disease consequences to any level desired and to observe the effect of this change on the rankings of candidates. The undesirability of conditions for morbidity category/ age group combinations are expressed as infant mortality equivalence (IME) values, that is, the number of acute morbidity days or chronic cases considered to be equal in undesirability to an infant death. The perspective used as an example throughout this report reflects the median of responses from public health professionals in a variety of developing countries (elicited by means of a questionnaire—see Appendix E). The median values are shown in Table 1.3. Other perspectives could be used, for example, an “age-neutral” perspective. The effect on rankings of using other perspectives is discussed. The committee, however, does not endorse any particular perspective for policy formulation in this area. Different rankings may result from the adoption of different viewpoints on the undesirability of illness and death at different stages of life.


See Appendix F for information on the computer software used in this analysis.

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