We observed a total of 4271 drug administrations for 720
patients: 2592 administrations for 514 patients at hospital
A and 1679 for 206 patients at hospital B. The mean
age of patients differed by hospital: 72.6 years (95% CI,
71.1-74.0) for hospital A and 67.5 years (95% CI, 65.0-
70.0) for hospital B.