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Homelessness flag

homelessness.Rd

homelessness() returns homelessness status for each genc_id based on ICD-10-CA diagnosis codes Z59.0 or Z59.1.

Coding of homelessness became mandatory in 2018. We therefore recommend that users only only apply this function to encounters discharged since 2018 (see below for details).

For data since 2018, previous studies have shown that ICD-10-CA codes have a sensitivity of 60-70% for detecting whether a patient has experienced homelessness at the time of hospitalization (Richard et al, 2024).

Usage

homelessness(cohort, ipdiag, erdiag)

Arguments

cohort

(data.frame or data.table) Cohort table with all relevant encounters of interest, where each row corresponds to a single encounter. Must contain GEMINI Encounter ID (genc_id).

ipdiag

(data.table) ipdiagnosis table as defined in the GEMINI Data Repository Dictionary. This table must contain genc_id and diagnosis_code (as ICD-10-CA alphanumeric code) in long format.

erdiag

(data.table) erdiagnosis table as defined in the GEMINI Data Repository Dictionary. This table must contain genc_id and er_diagnosis_code (as ICD-10-CA alphanumeric code) in long format.

Typically, ER diagnoses should be included when deriving the homelessness flags in order to increase sensitivity. However, in certain scenarios, users may choose to only include IP diagnoses by specifying erdiag = NULL. This may be useful when comparing cohorts with different rates of ER admissions.

Value

data.table with the same number of rows as input cohort with an additional derived boolean field labelled as "homelessness_icd__flag". Possible values are TRUE, FALSE or NA. NA indicates that an encounter does not have a diagnosis code in the diagnosis table input.

Details

Below are the current ICD-10-CA codes related to homelessness, which are coded regardless of the diagnosis type. For more information, please refer to the references in this page.

  • Z59.0: For confirmed homelessness assign Z59.0.

  • Z59.1: For confirmed inadequate housing due to factors relating to safety or accessibility, but not necessarily a complete lack of housing assign Z59.1.

Homelessness (Z59.0) is coded when an individual is determined to be homeless. Effective of the year 2018-2019, CIHI mandated that Z59.0 is to be coded when a "patient's record shows that they are homeless upon admission". After the mandate, prevalence of the flag increased by 84% compared to the previous year, suggesting that ICD-10-CA diagnosis codes underestimate true homelessness rates prior to the reporting mandate. (For details, see 2018 CIHI mandate to code homelessness)

Inadequate housing (Z59.1) is coded when an individual is determined to be experiencing poor housing conditions, their usual housing is uninhabitable, or if they are experiencing a lack of utilities. Some examples include unsafe living conditions, safety issues such as a lack of heating, and if the home isn't safely inhabitable due to repairs in progress.

References

Examples

if (FALSE) { # \dontrun{
drv <- dbDriver("PostgreSQL")
dbcon <- DBI::dbConnect(drv,
  dbname = "db",
  host = "domain_name.ca",
  port = 1234,
  user = getPass("Enter user:"),
  password = getPass("password")
)
ipadm <- dbGetQuery(dbcon, "select * from admdad") %>% data.table()
ipdiagnosis <- dbGetQuery(dbcon, "select * from ipdiagnosis") %>% data.table()
erdiagnosis <- dbGetQuery(dbcon, "select * from erdiagnosis") %>% data.table()
homeless <- homelessness(cohort = ipadm, ipdiag = ipdiagnosis, erdiag = erdiagnosis)
# view only genc_id's with homelessness flag
homeless <- homeless %>% filter(homeless$homelessness_icd_flag == TRUE)
} # }