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WARDEN: Workflows for health technology Assessments in R using Discrete EveNts

Introduction

WARDEN is a user-friendly package that facilitates the use of discrete event simulations without resource constraints for cost-effectiveness analysis. The package supports a flexible, transparent, practical approach to discrete event simulation while keeping an acceptable performance.

The current version supports:

  • Discrete event simulation models, Markov/semi-Markov models and hybrid models using parallel and non-parallel engines
  • Seamlessly integrating data.frames and other objects into the model
  • Delayed execution of the main inputs to facilitate readability of the model
  • Implementation of structural and parameter uncertainty
  • Helper functions to facilitate drawing of time to events and the use of hazard ratios, as well as other functions to facilitate transparency
  • Performing cost-effectiveness and uncertainty analysis

It is recommended that the user checks the vignettes, first the simple Sick-Sicker-Dead model and then the more complex model for early breast cancer. The markov example shows how to run a cohort Markov model while using the same modeling framework. Similarly, a simulation based Markov model could be run. Structural and parametric uncertainty are explored in the corresponding vignette. The IPD vignette shows how WARDEN can be used when individual patient data is available.

Documentation

Have a look at the package home site for more details on documentation and specific tutorials.

For more details on the code, check our Github repository, or our CRAN site.

Installation

WARDEN can now be installed directly from CRAN or this repo via

install.packages("WARDEN") #CRAN version 

# install.packages("devtools")
devtools::install_github("jsanchezalv/WARDEN", ref="main") #github version

Citation

If you use WARDEN, please contact the authors for the most up to date appropriate citation.

WARDEN

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Version

Install

install.packages('WARDEN')

Monthly Downloads

533

Version

1.2.4

License

GPL (>= 3)

Maintainer

Javier Sanchez Alvarez

Last Published

July 4th, 2025

Functions in WARDEN (1.2.4)

pcond_gompertz

Survival Probaility function for conditional Gompertz distribution (lower bound only)
disc_ongoing_v

Calculate discounted costs and qalys between events for vectors
disc_ongoing

Calculate discounted costs and qalys between events
pick_psa

Helper function to create a list with random draws or whenever a series of functions needs to be called. Can be implemented within pick_val_v.
pick_val_v

Select which values should be applied in the corresponding loop for several values (vector or list).
disc_cycle

Cycle discounting
qgamma_mse

Use quantiles from a gamma distribution based on mean and se
qcond_gompertz

Quantile function for conditional Gompertz distribution (lower bound only)
qbeta_mse

Draw from a beta distribution based on mean and se (quantile)
qcond_llogis

Conditional quantile function for loglogistic distribution
extract_psa_result

Extract PSA results from a treatment
disc_cycle_v

Cycle discounting for vectors
luck_adj

Perform luck adjustment
qtimecov

Draw Time-to-Event with Time-Dependent Covariates and Luck Adjustment
modify_event

Modify the time of existing events
qcond_lnorm

Conditional quantile function for lognormal distribution
rpoisgamma

Draw time to event (tte) from a Poisson or Poisson-Gamma (PG) Mixture/Negative Binomial (NB) Process
modify_item

Modify the value of existing items
qcond_norm

Conditional quantile function for normal distribution
run_sim

Run the simulation
qcond_weibull

Conditional quantile function for weibull distribution
rcond_gompertz

Draw from a conditional Gompertz distribution (lower bound only)
rcond_gompertz_lu

Draw from a Conditional Gompertz distribution (lower and upper bound)
modify_item_seq

Modify the value of existing items
rdirichlet_prob

Draw from a dirichlet distribution based on mean transition probabilities and standard errors
new_event

Generate new events to be added to existing vector of events
rdirichlet

Draw from a dirichlet distribution based on number of counts in transition. Adapted from brms::rdirichlet
qcond_exp

Conditional quantile function for exponential distribution
qcond_gamma

Conditional quantile function for gamma distribution
random_stream

Creates an environment (similar to R6 class) of random uniform numbers to be drawn from
summary_results_sim

Summary of PSA outputs for a treatment
qcond_weibullPH

Conditional quantile function for WeibullPH (flexsurv)
replicate_profiles

Replicate profiles data.frame
rgamma_mse

Draw from a gamma distribution based on mean and se
tte.df

Example TTE IPD data
summary_results_sens

Summary of sensitivity outputs for a treatment
summary_results_det

Deterministic results for a specific treatment
run_sim_parallel

Run simulations in parallel mode (at the simulation level)
sens_iterator

Create an iterator based on sens of the current iteration within a scenario (DSA)
rbeta_mse

Draw from a beta distribution based on mean and se
add_item

Define parameters that may be used in model calculations (list)
cond_dirichlet

Calculate conditional dirichlet values
cond_mvn

Calculate conditional multivariate normal values
create_indicators

Creates a vector of indicators (0 and 1) for sensitivity/DSA analysis
ceac_des

Calculate the cost-effectiveness acceptability curve (CEAC) for a DES model with a PSA result
add_tte

Define events and the initial event time
add_reactevt

Define the modifications to other events, costs, utilities, or other items affected by the occurrence of the event
ast_as_list

Transform a substituted expression to its Abstract Syntax Tree (AST) as a list
adj_val

Adjusted Value Calculation
add_item2

Define parameters that may be used in model calculations (uses expressions)
evpi_des

Calculate the Expected Value of Perfect Information (EVPI) for a DES model with a PSA result
disc_instant

Calculate instantaneous discounted costs or qalys
disc_instant_v

Calculate instantaneous discounted costs or qalys for vectors
draw_tte

Draw a time to event from a list of parametric survival functions
extract_elements_from_list

Extracts items and events by looking into assignments, modify_item, modify_item_seq, modify_event and new_event
extract_from_reactions

Extract all items and events and their interactions from the event reactions list