icd9cm_elixhauser_ahrq37 {medicalrisk}

Create AHRQ v3.7 map of ICD-9-CM to Elixhauser comorbidities

Description

Function makes a dataframe that links ICD-9-CM codes to the Elixhauser comorbidity categories using the AHRQ v3.7 mapping.

Usage

icd9cm_elixhauser_ahrq37(icd9)

Arguments

icd9

a unique character vector of ICD-9-CM codes

Details

Uses regular expressions based on the file "comformat2012-2013.txt" from AHRQ.

The Agency for Healthcare Research and Quality (AHRQ) has developed Comorbidity Software as part of the Healthcare Cost and Utilization Project (HCUP). The software was developed to report on the comorbidity measures reported by Elixhauser (1998).

The AHRQ software has two parts, one that classifies ICD-9-CM codes by comorbidity, and another that performs heuristics to eliminate duplicate comorbidities and ignore comorbidities which are the primary reason for the hospital visit, as per the DRG.

This table is a translation of the first part of the software, the classifier, as implemented in the SAS file Comformat2012-2013.txt.

ICD-9-CM codes must have periods removed. Diagnostic codes are prefixed with 'D' while procedure codes are prefixed with 'P'. So, diagnostic code 404.03 should be "D40403".

Value

A data frame, with ICD9 codes as row names and one logical column for each comorbidity in elixhauser_list

References

1. http://www.hcup-us.ahrq.gov/toolssoftware/comorbidity/comorbidity.jsp

See Also

icd9cm_charlson_deyo, icd9cm_charlson_romano, icd9cm_charlson_quan, icd9cm_elixhauser_quan

Examples

# Identify Elixhauser categories
cases <- data.frame(id=c(1,1,1,2,2,2),
  icd9cm=c("D20206","D24220","D4439","D5064","DE8788","D40403"),
  stringsAsFactors=TRUE)
cases_with_cm <- merge(cases, icd9cm_elixhauser_ahrq37(levels(cases$icd9cm)),
  by.x="icd9cm", by.y="row.names", all.x=TRUE)

# generate crude comorbidity summary for each patient
library(plyr)
ddply(cases_with_cm, .(id),
  function(x) { data.frame(lapply(x[,3:ncol(x)], any)) })