ICD -9

elixhauser i9_dx1-i9_dx40, index(9) idvar(unique_id) diagprfx(i9_dx) smelix cmorb

ICD - 10

elixhauser i10_dx1-i10_dx40, index(10) idvar(unique_id) diagprfx(i10_dx) smelix cmorb

To adapt your Elixhauser comorbidity index calculation for ICD-9 codes in Stata, you need to:

1. Change the prefix from i10_dx (for ICD-10) to i9_dx (for ICD-9).
2. Ensure that the index() option correctly references ICD-9.
3. Use the correct Elixhauser comorbidity classification method for ICD-9.

Explanation of Parameters

• i9_dx1-i9_dx40: These are the variables containing ICD-9 diagnosis codes.
• index(9): Specifies that the diagnosis codes are ICD-9 (use index(10) for ICD-10).
• idvar(unique_id): Identifies the patient ID variable.
• diagprfx(i9_dx): Specifies that diagnosis variables are prefixed with i9_dx.
• smelix: Requests summary Elixhauser comorbidity scores.
• cmorb: Requests binary indicators for individual Elixhauser conditions.