To be eligible for inclusion in the BIS, participants had to be insured by the AOK Nordost, at least 70 years old, and living in Berlin at the time of recruitment. Individuals who required kidney dialysis, had undergone kidney transplantation, or were care-dependent at the beginning of the study were excluded from the sample as opposed to participants who met these criteria during the course of the study. From the 166,500 individuals insured by the AOK Nordost who were living in Berlin and aged 70 and older, invitations to a free kidney check-up were sent to 16,701 randomly selected potential participants in a total of 12 rounds. Potential participants were offered the opportunity to select the most suitable study location for them from 13 locations spread across Berlin. Registration for the study took place via a toll free hotline number.

Dear study participants,

As the project leaders of the BIS we would like to express our deepest appreciation for your loyalty and support! 

We have been running the BIS for more than 10 years and we are very touched by your support for us in our endeavors over the years. Without you we would not be able to pursue our goal of achieving a healthier society. Once more, on behalf of the BIS Team and the scientific community, thank you very much!

Stay safe!