to display a selection of causes which may have public health importance in different settings.

Table 8 represents an attempt to categorise selected major causes of death according to whether they are likely to be diagnosed or excluded based on symptoms reported by relatives. Clearly the possibility of exclusion of a diagnosis depends on whether the deceased suffered from a condition with similar symptoms. For example, stomach cancer could be excluded if the deceased had been well until shortly before death and suddenly developed a severe respiratory infection which proved fatal, but could not be excluded if the deceased in addition gave a history suggestive of a chronic peptic ulcer. The potential value of the exclusion category l. that it provides an upper limit to the rate of mortality from any given cause.

In 1978, the World Health Organization produced a list of symptoms associated with possible diagnoses, for use in the lay reporting of morbidity and mortality (WHO, 1978), stating that the list was to be regarded as an example needing modification and adaptation to fit differing local circumstances. Garenne and Fontaine (1986) and Zimicki (1989) have pointed out the limitations of this list.

An alternative approach to the collection of detailed information on symptomatology is the use of diagnostic algorithms (Essex, 1980). These have been used mainly in developing countries, to assist W paramedical workers with the diagnosis and treatment of common illnesses. They are based on step by step exclusion of possible alternative diagnoses for each symptom reported by a patient. An algorithm is provided for each of the major common symptoms, for example cough, fever, oedema, weight loss and so on. The interviewer works through the algorithms corresponding to each of the principal symptoms experienced by the deceased, and the Zinal diagnoses given by these algorithms should agree. An example of a diagnostic algorithm is given in Figure 1.

How applicable existing algorithms developed' for the questioning of living patients are to the retrospective question'ing of surviving relatives remains to be ascertained. The availabl,' algorithms would require adaptation for this purpose, and this woulc be a major undertaking. The number of diagnoses would need tc. be reduced to encompass only fatal diseases, and pathways adapted to permit broader diagnostic groupings in cases where the presence or absence of particular symptoms cannot be determined. Algorithms may need to be country- or area-specific bacause of variations in the endemicity of different diseases. Extensive field testing and validation would be required to establish how appropriate algorithms are in this context. The development of a set of algorithms for the determination of cause of death based on symptoms reported by surviving relatives that proved to be valid in a range of settings would represent a valuable addition to the tools available for epidemiological work in developing countries.

The use of algorithms would require more highly trained interviewers and a lengthier interview. Computer programs have been developed for use with small portable computers in order to facilitate the use of diagnostic algorithms in the field, and the feasibility of this approach needs to be assessed (Zimicki, 1989).

22