Free-text fields change the meaning of coded data

Researchers have advocated the supplementation of coded fields with free-text fields in electronic medical records (EMRs) to provide clinicians with flexibility during data entry. They cite advantages of more complete data capture and improved clinician acceptance and use of the EMR. However, free text may have the disadvantage of changing the meaning of coded data, which causes lower data accuracy for applications that cannot read free text. We studied the free-text entries that clinicians made during the recording of medication data. We found that these entries changed the meaning of coded data and lowered data accuracy for the medical decision-support system (MDSS) in our EMR. We conclude that supplemental free-text entries made by clinicians frequently alter the meaning of coded data.