151 general practitioners participated and were randomly allocated to 1 of 3 intervention options: (1) brief advice by the physician; (2) individually tailored computer-generated tailored letters; or (3) a combination of these. ###>151 general practitioners participated and were randomly allocated to 1 of 3 intervention options: (1) brief advice by the physician; (2) individually tailored computer-generated tailored letters; or (3) a combination of these.