These are the three factors hospitals are looking at in deciding where to replace bar codes with RFID. (Picture from Accurate Data Systems.)
Despite the calls by some experts to "skip" bar codes and go straight to chips, most hospitals know this is impossible. Chips cost much more than bar codes, the readers cost money, and there are worries about radio interference.
New Zealand has been wrestling with this question, and finally decided to bar code patients, clinicians and medicine bottles. All three tags are scanned with each dose, and the data eventually makes its way into the hospitals IT infrastructure.
On the other hand bottles of medicine in storage have bar codes, because of their higher value. English hospitals have also begun using RFID chips on patients in emergency rooms, who tend to move around a lot.
Thus the three factors determining where hospitals will chip and where they will bar code. The more mobile, the more valuable, and the more distant the reader, the more likely RFID will be needed. Otherwise, the bar code revolution will remain in force.