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The article presents different mathematical algorithms intending to quantify the "potential years of life lost" based on life table models, and on real age-structured populations, respectively. Applying these algorithms to accident and cardiovascular mortality data from Berlin (West) demonstrates their individual and specific relevance.

The article gives algorithms to calculate mean ages at death for specific causes, based on life table models. Parameters of interest are death due to a specific cause, dying after the "elimination" of the specific cause, or the transition into a "new" structure of mortality when a specific cause of death vanishes. The setbacks of widely used calculations are discussed in this context. These different approaches are demonstrated by means of data pertaining to accident and cardiovascular mortality of the male population of Berlin (West). The estimated impact on life expectancy varies according to both the mathematical model and the specific cause of death: differences are negligible in mortality due to accidents, whereas the results differ considerably in cardiovascular causes of death. The algorithm suggested allows to constrain the calculations to specific age groups. Topics such as "avoidable death" and "health objectives" have to be aware of these different methods.

The formal mathematical steps of direct and indirect standardisation are deduced and it is pointed out that standardisation is an analytical concept for processing data within the framework of structurised populations to enable correct interpretation of these data in a manner modified according to specific problems. In particular, this concept is not confined to transforming age-structured mortality data of a population to the age distribution of the members of a larger population by means of a rule of three. Standardisation is in fact a model of the macrolevel (population). It makes no demands on the modalities of structuring. The structure selected as standard is arbitrarily set. With time series, standardisation usually modifies only the levels of the figures and not the frequencies. The results of standardisation are in every case valid only if the standard is also stated. A rule of thumb is: In retrospective analysis it is meaningful to standardise on the structure at the beginning or end of the time series; in extrapolations standardisation should be performed on the last structure that had been determined, whereas for comparisons a median structure should be standardised. The standardisation approach can be used in case of weighted arithmetic, geometric or harmonic means. Before effecting standardisation, the type of connection between the employed data should be examined. The examples of concepts of direct standardisation refer to cardiovascular and accident mortality in West Berlin from 1963 to 1991, whereas those of indirect standardisation are based on the accident mortality in West Berlin in 1987 structured according to city districts.

Following a long-term decline, death rates due to infectious diseases in West-Berlin men have dramatically increased since 1983. The Berlin mortality statistics introduced AIDS as a specific cause of death only in 1989. However, opportunistic infections, a negligible quantity until 1983, and pointing to AIDS as the underlying cause, show a steep increase in the mid and late eighties. In terms of Potential Years of Life Lost, AIDS-related mortality amounts to 8 percent of total mortality in West-Berlin men in 1989/1990.