Identify episodes of care

The episodes_of_care() function groups encounters that are linked via transfers into a single episode of care. The derived episodes of care are used in the readmission() function to avoid counting transfers as readmissions. Therefore, the criteria for transfers used in this function are based on CIHI guidelines for readmission calculations. However, the episodes_of_care function can also be used independently to compute episodes of care outside of readmission.

Transfer information is obtained from the GEMINI database table lookup_transfer (see GEMINI database schema). By default, the function queries all encounters in the admdad table to ensure that any encounters that may be linked via transfers are accurately grouped into the same episode of care.

Note: Users do not typically need to calculate episodes of care themselves, but rather should use the derived epicares variable in the GEMINI database, if available. This is due to the fact that the derived variable is calculated based on all available GEMINI encounters, and therefore, provides the most accurate identification of episodes of care. By contrast, datacuts or cohorts that have been pre-filtered may miss certain encounters, resulting in a loss of information. However, in certain situations, users may still find this function useful 1) to understand how the derived variable is calculated and 2) in case users need to re-calculate episodes of care or readmission rates for a restricted cohort (see below).

Usage

episodes_of_care(dbcon, restricted_cohort = NULL)

Arguments

dbcon: (DBIConnection)
A database connection to any GEMINI database.
restricted_cohort: (data.table | data.frame)
User specified cohort that is a restricted subset of all encounters in DRM table "ipadmdad" (see GEMINI Data Repository Dictionary). Must contain genc_id as the identifier. Default is Null, which loads the entire "ipadmdad" table in the user-provided database (recommended approach).

Value

(data.frame)
This function returns a data.table excluding records with invalid patient_id_hashed, age < 18, or admit_category of cadaveric donors in line with CIHI guidelines. Nine columns are returned: genc_id, patient_id_hashed, time_to_next_admission (numeric), time_since_last_admission (numeric), AT_in_coded (TRUE/FALSE), AT_out_coded (TRUE/FALSE), AT_in_occurred (TRUE/FALSE/NA), AT_out_occurred (TRUE/FALSE/NA), epicare (numeric)

Details

An episode of care refers to all contiguous inpatient hospitalizations admitted to any medical or intensive care service within GEMINI. Episodes involving inter-facility transfers are linked regardless of diagnosis. An acute care transfer is assumed to have occurred if either of the following criteria are met (see CIHI guidelines:

An admission occurs within 7 hours after discharge, regardless of whether the transfer is coded by hospitals. OR
An admission occurs within 7-12 hours after discharge, and at least one hospital has coded the transfer.

Acute transfers that are coded by hospitals (AT_in_coded and AT_out_coded) are defined by the DAD fields institution_from and institution_to: AT_in_coded/AT_out_coded is TRUE, when 'institution_from == "AT" or 'institution_to == "AT". All remaining entries are set to FALSE.

Acute transfers that actually occurred (AT_in_occurred and AT_out_occurred) are defined as follows: AT_in_occurred/AT_out_occurred is TRUE when admission is within 7 hrs of discharge regardless of transfer coding, or, admission is within 7-12hrs of discharge and at least one hospital coded the transfer. AT_in_occurred/AT_out_occurred is NA when the transfer was coded but admission time since previous discharge is unknown. This is because it cannot be determined if the transfer actually took place or not. AT_in_occurred/AT_out_occurred is FALSE, for all remaining entries.

Each episode of care (epicare) is defined by linked transfers identified based on AT_in_occurred/ AT_out_occurred. A unique numeric ID is assigned to each unique episode of care. That is, contiguous encounters linked by transfers will have the same epicare number.

Note

We recommend that users run this function on the entire GEMINI data set (the default setting) to ensure no transfers to/from are omitted. Please review the function documentation & vignette carefully. A comprehensive understanding of the following concepts is needed for proper use of the function: transfer coded vs. transfer occurred, episode of care definition.

References

CIHI readmission guidelines

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"))

epicare_table <- episodes_of_care(dbcon)
} # }