I10_NDX indicates the total number of ICD-10-CM diagnoses (valid and invalid) coded on the discharge record. In assigning I10_NDX, the first listed diagnosis is included in the count, even if it is blank, so long as there is a secondary diagnosis present (see table below).
Beginning with the 2017 HCUP databases, external cause of morbidity codes are included with other diagnoses in the diagnosis-related data elements (I10_DXn, I10_NDX, and DXPOAn) and are no longer retained in separate data elements (I10_ECAUSEn, I10_NECAUSE, and E_POAn).
For data prior to the fourth quarter of 2015, the count of the number of diagnoses is stored in the data element NDX to indicate the use of the ICD-9-CM coding system.
Value |
Description |
0 |
No ICD-10-CM diagnoses are coded on the record |
1 |
Only the first listed diagnosis (I10_DX1) is coded. All secondary diagnoses are blank. |
2 |
One secondary diagnosis (I10_DX2) is coded. The first listed diagnosis (I10_DX1) may be coded or blank. |
3 |
The second and third diagnoses (I10_DX2 and I10_DX3) are coded. The first listed diagnosis (I10_DX1) may be coded or blank. |
etc. |
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