You definitely don't want to stretch the truth on this answer. The interviewer may already know the answer to this question if they have called your references already. If you aren't proud of your accuracy, tell the interviewer that you are making a point to slow down and pay more attention to detail. If you excel at your job and its accuracy then brag a little and throw your boss's name in there as a reference.
"Our accuracy wasn't necessarily tracked, but the smooth flow of patients, appointments, interaction with co-workers and my supervisor's positive feedback showed me that I was doing a good job."