In outpatient data, the reasons for visit (I10_DX_Visit_Reasonn, where n has a value 1-3) includes diagnosis codes describing the patient's stated reason for seeking care (or as stated by the patient's representative). This may be a condition representing patient distress, an injury, a poisoning, or a reason or condition (not illness or injury) such as follow-up or pregnancy in labor. Reported first is the diagnosis code describing the patient's primary reason for seeking care. There are up to two other diagnosis code reporting additional reasons for the patient's visit or care.
I10_DX_Visit_Reason is an ICD-10-CM diagnosis code. Diagnoses are compared to a list of ICD-10-CM codes valid for the discharge date. Anticipation of or lags in response to official ICD-10-CM coding changes are permitted for discharges occurring within a window of time around the official ICD-10-CM coding changes (usually October 1). Beginning in the 1998 data, a year window (six months before and six months after) is allowed. Invalid diagnoses are set to "invl".
For data prior to the fourth quarter of 2015, the reason for diagnosis is stored in the data element DX_Visit_Reason to indicate the use of the ICD-9-CM coding system.