Of the 10 313 randomly selected individuals, 882 subjects were excluded according to the following criteria: unable to speak or understand German (n = 637), dead, severely ill or senile (n = 137), away for an extended period of time (n = 52) or hearing impaired (n = 56). A response rate of 21.23% was achieved in the study, which corresponded to a net sample size of 2002 persons, 982 men and 1020 women.