This study examined differences in the treatment duration written in an opioid prescription versus the duration associated with the dosing frequency and number of pills per day. Over a 22-month period, nearly 17% of opioid prescriptions were for a duration greater than what was documented in the prescription. The study found that making the opioid prescription duration a required field in the electronic health record (EHR) reduced the discrepancy between the written and calculated durations but did not eliminate the discrepancies.