dshr

An R package that implements the methods to derive disease-specific hazard ratios (dsHR) from overall hazard ratios (oHR) described in the publication:

• Alarid-Escudero F, Kuntz KM “Potential bias associated with modeling the effectiveness of healthcare interventions in reducing mortality using an overall hazard ratio.” PharmacoEcon 2020; 38(3):285-296. https://doi.org/10.1007/s40273-019-00859-5

Installation

You can install the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("feralaes/dshr")

Example

This is a basic example which shows you how to derive a disease-specific hazard ratio (dsHR) from a disease-specific mortality rate, an overall hazard ratio (oHR) reported in a trial, the initial age of the cohort in the trial, and the length of the trial using an empirical approach with background mortality from US life tables.

library(dshr)
ohr        <- 0.55 # Overall hazard ratio (oHR)
n_age_init <- 50   # Initial age of cohort in trial
trial_time <- 5    # Length of clinial trial in years
mu_Dis     <- 0.05 # Disease-specific mortality rate

dshr_emp <- calc_dshr_from_ohr(ohr = ohr, 
                               mu_Dis = mu_Dis,
                               n_age_init = n_age_init, 
                               trial_time = trial_time, 
                               hazard = "empirical")
dshr_emp
#>      dshr 
#> 0.5038836

To estimate dsHR assuming an anlaytical functional form of background mortality (either exponential, linear or geometric), estimate the mu0 and alpha parameters of the functional form, type them in calc_dshr_from_ohr and substitute empirical with the functional form of interest. For example, using an exponential functional form with background mortality from US life tables, the estimated parameters are

coef_hazard_exp <- est_hazard_params(n_age_init = n_age_init,
                                     trial_time = trial_time,
                                     hazard = "exponential")
coef_hazard_exp
#> $mu0
#>  (Intercept) 
#> 0.0001105985 
#> 
#> $alpha
#>        Age 
#> 0.07362561

and the dshr is

dshr_exp <- calc_dshr_from_ohr(ohr = ohr, 
                               mu_Dis = mu_Dis,
                               n_age_init = n_age_init, 
                               trial_time = trial_time, 
                               mu0 = coef_hazard_exp$mu0,
                               alpha = coef_hazard_exp$alpha,
                               hazard = "exponential")
dshr_exp
#>      dshr 
#> 0.5022318