# Cohort diagnostics

## Introduction

In this example we’re going to summarise cohort diagnostics results for cohorts of individuals with an ankle sprain, ankle fracture, forearm fracture, or a hip fracture using the Eunomia synthetic data.

Again, we’ll begin by creating our study cohorts.

    library(CDMConnector)
    library(CohortConstructor)
    library(CodelistGenerator)
    library(CohortCharacteristics)
    library(CohortSurvival)
    library(PhenotypeR)
    library(dplyr)
    library(ggplot2)

    con <- DBI::dbConnect(duckdb::duckdb(),
                          CDMConnector::eunomiaDir("synpuf-1k", "5.3"))
    cdm <- CDMConnector::cdmFromCon(con = con,
                                    cdmName = "Eunomia Synpuf",
                                    cdmSchema   = "main",
                                    writeSchema = "main",
                                    achillesSchema = "main")

    cdm$injuries <- conceptCohort(cdm = cdm,
      conceptSet = list(
        "ankle_sprain" = 81151,
        "ankle_fracture" = 4059173,
        "forearm_fracture" = 4278672,
        "hip_fracture" = 4230399
      ),
      name = "injuries")

## Cohort diagnostics

We can run cohort diagnostics analyses for each of our overall cohorts like so:

    cohort_diag <- cohortDiagnostics(cdm$injuries,
                                     matchedSample = NULL,
                                     survival = TRUE)

Cohort diagnostics builds on CohortCharacteristics and CohortSurvival R packages to perform the following analyses on our cohorts:

- Cohort count: Summarises the number of records and persons in each one of the cohorts using summariseCohortCount().
- Cohort attrition: Summarises the attrition associated with the cohorts using summariseCohortAttrition().
- Cohort characteristics: Summarises cohort baseline characteristics using summariseCharacteristics(). Results are stratified by sex and by age group (0 to 17, 18 to 64, 65 to 150). Age groups cannot be modified.
- Cohort large scale characteristics: Summarises cohort large scale characteristics using summariseLargeScaleCharacteristics(). Results are stratified by sex and by age group (0 to 17, 18 to 64, 65 to 150). Time windows (relative to cohort entry) included are: -Inf to -1, -Inf to -366, -365 to -31, -30 to -1, 0, 1 to 30, 31 to 365, 366 to Inf, and 1 to Inf. The analysis is perform at standard and source code level.
- Cohort overlap: If there is more than one cohort in the cohort table supplied, summarises the overlap between them using summariseCohortOverlap().
- Cohort timing: If there is more than one cohort in the cohort table supplied, summarises the timing between them using summariseCohortTiming().
- Cohort survival: If `survival = TRUE`, summarises the survival until the event of death (if death table is present in the cdm) using
  estimateSingleEventSurvival().

The analyses cohort characteristics, cohort age distribution, cohort large scale characteristics, and cohort survival will also be performed (by default) in a matched cohort. The matched cohort will be created based on year of birth and sex (see matchCohorts() function in CohortConstructor package). This can help us to compare the results in our cohorts to those obtain in the matched cohort, representing the general population. Notice that the analysis will be performed in: (1) the original cohort, (2) individuals in the original cohorts that have a match (named the sampled cohort), and (3) the matched cohort.

As the matched process can be computationally expensive, specially when the cohorts are very big, we can reduce the matching analysis to a subset of participants from the original cohort using the `matchedSample` parameter. Alternatively, if we do not want to create the matched cohorts, we can use `matchedSample = 0`.

The output of `cohortDiagnostics()` will be a summarised result table.

## Visualise cohort diagnostics results

We will now use different functions to visualise the results generated by CohortDiagnostics. Notice that these functions are from CohortCharacteristics and CohortSurvival R packages packages. ### Cohort counts

    tableCohortCount(cohort_diag)

### Cohort attrition

    tableCohortAttrition(cohort_diag)

    plotCohortAttrition(cohort_diag)

### Cohort characteristics

    tableCharacteristics(cohort_diag)

### Cohort large scale characteristics

    tableLargeScaleCharacteristics(cohort_diag)

### Cohort overlap

    tableCohortOverlap(cohort_diag)

    plotCohortOverlap(cohort_diag)

### Cohort timing

    tableCohortTiming(cohort_diag)

    plotCohortTiming(cohort_diag)

### Cohort survival

    tableSurvival(cohort_diag, header = "estimate_name")

    plotSurvival(cohort_diag, colour = "target_cohort", facet = "cdm_name")