*! version 1.0.0 16dec2022

Title

elix22 -- Calculate Elixhauser comorbidity measures (version 2022.1)

Syntax

elix22 varlist [if] [in]
[, id(varname)]

where varlist includes one or more diagnosis fields containing ICD-10-CM codes valid from October 2015 through September 2022

Options

id(varname) specifies the patients' identifier. id() should be specified when the data contain multiple observations
per patient and it is desired to compute comorbidities across all observations within patients. When id() is not specified (the default),
Elixhauser comorbidities are computed separately for each observation in the data.

Description

elix22 computes Elixhauser comorbidities based on ICD-10-CM codes valid from October 2015 through September 2022.
This updated Elixhauser version (2022.1) was developed as part of the Healthcare Cost and Utilization Project (HCUP),
a Federal-State-Industry partnership sponsored by the Agency for Healthcare Research and Quality. The number of comorbidity
measures increases from 29, in the original Elixhauser specifications (Elixhauser et al. 1998), to 38 starting in v2021.1,
with three measures added, five measures modified to create 12 more specific measures, and one measure discontinued.
Detailed information about Elixhauser version 2022.1 can be found at:
https://www.hcup-us.ahrq.gov/toolssoftware/comorbidityicd10/comorbidity_icd10.jsp.

Remarks

The Elixhauser comorbidities version (2022.1) specifications rely on present on admission (POA) indicators to compute a subset
of the comorbidity measures where the place of service is the hospital. elix22 computes those comorbidity measures
using all of the ICD-10-CM codes (i.e. ignoring POA). The reason for this is because the plurality of health care is provided in the
outpatient setting where POA is irrelevant. elix22 therefore captures all the possible ICD-10-CM to identify comorbidities
regardless of setting in which healthcare was administered.

Elixhauser comorbidities are intended to identify pre-existing conditions based on secondary diagnoses listed on hospital administrative data.
However, researchers may want to apply elix22 across all available diagnosis fields in order to identify categories of disease conditions
(whether or not they represent "comorbitities" per se). In the former case, the user can limit the diagnoses fields to the secondary diagnosis
onward. In the latter case, the user can include all diagnosis fields available in the data. See the examples below for a demonstration of these applications.

Examples

Use elix22 across all available diagnosis fields in order to identify
categories of disease conditions (whether or not they represent "comorbitities" per se).

. use example_data.dta, clear

. elix22 dx1-dx10, i(id)

Use elix22 to compute commorbidities using diagnosis fields 2 through 10.

. use example_data.dta, clear

. elix22 dx2-dx10, i(id)

Use elix22 to compute commorbidities using only primary diagnosis (dx 1).

. use example_data.dta, clear

. elix22 dx1, i(id)

Use elix22 to compute commorbidities at the observation level (rather than at the aggregated patient level)

. use example_data.dta, clear

. elix22 dx2-dx10

References

Elixhauser, A., Steiner, C., Harris, D. R. and R. M. Coffey 1998. Comorbidity measures for use with administrative data. Medical Care 36:8-27.

Citation of elix22

elix22 is not an official Stata command. It is a free contribution
to the research community, like a paper. Please cite it as such:

Linden A. (2022). ELIX22: Stata module to compute Elixhauser commorbidity measures (version 2022.1)

Authors

Ariel Linden

President, Linden Consulting Group, LLC

alinden@lindenconsulting.org

Also see

Online: elixhauser (if installed)