# Introduction

CohortMethod is an R package for performing new-user cohort studies in an observational database in the OMOP Common Data Model.

# Features

• Extracts the necessary data from a database in OMOP Common Data Model format.
• Uses a large set of covariates for both the propensity and outcome model, including for example all drugs, diagnoses, procedures, as well as age, comorbidity indexes, etc.
• Large scale regularized regression to fit the propensity and outcome models.
• Includes function for trimming, stratifying and matching on propensity scores.
• Includes diagnostic functions, including propensity score distribution plots and plots showing covariate balance before and after matching and/or trimming.
• Supported outcome models are (conditional) logistic regression, (conditional) Poisson regression, and (conditional) Cox regression.

# Screenshots

 Propensity (preference score) distribution Covariate balance plot

# Technology

CohortMethod is an R package, with some functions implemented in C++.

# System Requirements

Requires R (version 3.6.0 or higher). Installation on Windows requires RTools. Libraries used in CohortMethod require Java.

# Installation

1. See the instructions here for configuring your R environment, including RTools and Java.

2. In R, use the following commands to download and install CohortMethod:

install.packages("remotes")
remotes::install_github("ohdsi/CohortMethod")
1. Optionally, run this to check if CohortMethod was correctly installed:
connectionDetails <- createConnectionDetails(dbms="postgresql",
server="my_server.org",
user = "joe",

checkCmInstallation(connectionDetails)

Where dbms, server, user, and password need to be changed to the settings for your database environment. Type

?createConnectionDetails

for more details on how to configure your database connection.

# User Documentation

Documentation can be found on the package website.

PDF versions of the documentation are also available: * Vignette: Single studies using the CohortMethod package * Vignette: Running multiple analyses at once using the CohortMethod package * Package manual: CohortMethod.pdf

# Contributing

Read here how you can contribute to this package.