Fig. 1

Participation in LIFE-Adult and in the short questioning, age range 40 to 79 years. Sample 1 of LIFE-Adult participants was used for the comparison with the Leipzig population and with short questionnaire participants using descriptive statistics (see Table 1). Sample 2 of LIFE-Adult participants was used for a more detailed comparison with short questionnaire participants using logistic regression (see Table 2, as well as the “Methods” section for further explanation). Invitation running refers to those invitees who had been sent an invitation few weeks before the end of the recruitment and who did not respond within that time frame. Persons willing to participate are those invitees who had agreed to participate in LIFE-Adult but did not get an appointment because the targeted total number of participants had been achieved. Refusals are those invitees who actively declined to participate by means of a response form enclosed in the invitation letters or by phone. Nonresponders are those invitees who entirely ignored the invitation. Data available for analysis refers to the number of non-missing data for each variable. Missing data include questioning and item nonresponse, the answer categories “I don’t know” and “refusal of answer”, and erroneous data. ISCED 97 = International Standard Classification of Education 1997