The Berlin Initiative Study (BIS) - A population-based aging cohort

Aging is a complex multidimensional process. It is important to understand the aging process at the level of body organs in order to differentiate between the physiological and pathological manifestations of aging. This also serves to answer the question: How much decline in organ function could be considered “normal” with increasing age meaning “reasonable for a given age”? Thus, the question arises as to what the threshold of organ function is at which the organ could still be regarded as healthy (i.e. below which disease begins). In turn, making this distinction has implications for the decision whether an individual should be considered ill and whether therapy is necessary or not.

It has been discussed for several years whether a purely binary classification into “ill” and “healthy” does justice to the functional adaptation throughout life course and whether the transitions are not smooth and should be adapted to the age in a more gradual manner (“age-adapted definitions”). This would have implications for epidemiological prevalence estimates within the context of healthcare research questions.

The kidney function has a model character. Currently, the staging system of chronic kidney disease applies to all age groups (Kidney Disease Improving Global Outcomes, KDIGO-Guidelines), regardless of whether a patient is 18 or 80 years old. Furthermore, there is a threshold value below which an individual is considered ill. However, a point of criticism is that, to date, the age-adaptation of the stages as well as of the threshold value is still lacking.

As for therapeutic approaches, it has been increasingly discussed whether the same treatment options could actually be suitable for all patients or do not have to be more individually tailored to the respective age (“one size does not fit all”). This applies in particular to invasive kidney transplantation and the alternative comprehensive conservative care in elderly frail individuals.