to compare because of differing methods of classification. There is therefore a clear need for an initiative to explore possible methods of producing reliable, useful and comparable data on causes of adult mortality, that could be applied in a wide range of developing countries.

# 3. SURVEY DESIGN FOR THE MEASUREMENT OF CAUSE-SPECIFIC ADULT MORTALITY

# 3.1 Introduction

'The measurement of adult mortality and its causes poses three fundamental problems that are not encountered in the case of childhood mortality. Firstly, adult deaths are relatively rare events, and large sample sizes are therefore needed to provide precise mortality estimates. Even larger samples are needed to provide a reliable indication of the percentage of deaths attributable to each cause. Secondly, unlike childhood deaths for which the mother or guardian is the natural informant, for adult deaths there is no single relative or associate that can always be used as an appropriate informant. Thirdly, it may be more difficult to obtain a reliable diagnosis through retrospective questioning for adult deaths than for childhood deaths. The first two problems, and other survey design issues are discussed in this section. Problems asssciated with the diagnosis and classification of causes of death are discussed in Section 4.

Given the need for reliable data on cause-specific adult mortality in developing countries, there are three basic approaches. The first is to take steps to increase the coverage and reliability of national systems for the collection of mortality data. In many countries, coverage levels of the formal vital registration system are currently extremely low outside the main urban centres. An alternative method of increasing coverage in rural areas w'ould be to involve primary health care workers in the maintenance of records of the births and deaths occurring in the communities for which they are responsible. Such community-based reporting systems might encourage a better understanding by health care workers of the communities they serve, and thus contribute to the development of effective primary health care. The gradual development of effective national systems for the collection of mortality data, either via community-based reporting or some other approach, should certainly be seen as an important long-term goal. Given the extensive training, supervision and coordination required to establish systems of this kind on a nationwide basis, however, such a process will clearly be lengthy. It seems very unlikely, therefore, that such an approach will yield useful and reliable data on adult mortality in the immediate future.

A second alternative is to make use of statistics collected at health care facilities. These data should not be neglected, but refer more often to morbidity than mortality, and may be affected by important biases. People attending hospitals or clinics are often unrepresentative of the general population. Use of a health facility will depend on the accessibility and acceptabi±ity of the services offered, and on their cost, both in terms of expenditure on treatment or transport and in terms of opportunity costs. These in turn will be affected by factors such as socio-economic status, ethnic group, 11