Continuous smoking abstinence rates over time

Mean continuous abstinence rates up to 52 weeks from the start of a quit attempt in clinical trials can be modelled with simple power functions for placebo, nicotine replacement therapy, bupropion and varenicline. This lets us predict abstinence at any point up to 52 weeks from any other point.

Usage

SmkContAbst(
  treatment = c("placebo", "varenicline", "bupropion", "nrt"),
  weeks = 4
)

Arguments

treatment

Character - the pharmacological support used for the quit attempt. One of "placebo", "varenicline", "bupropion", "nrt".

weeks

Numeric vector - weeks since the quit attempt started. The start of the attempt is week 0. Maximum 52.

Value

A vector of probabilities that the person is still abstinent.

Details

The equations are taken from Supplementary Figure 2 of:

Jackson SE, Kotz D, West R, Brown J (2019). Moderators of real-world effectiveness of smoking cessation aids: a population study. Addiction 114(9):1627-1638. doi:10.1111/add.14549

This function used to live in stapmr. It has been moved here because data-raw/Relapse_Hawkins2010/prep_Hawkins_relapse.R needs it to build hawkins_relapse, and stapmr is a private package, so anyone outside the group could not rebuild the package data. There is nothing in the function that needs stapmr: it is four curves and no dependencies.

Note the curves are only fitted out to 52 weeks. Do not ask it for anything beyond that.

Examples

if (FALSE) { # \dontrun{

# Continuous abstinence over the first four weeks
SmkContAbst("placebo", 0:4)
# 1.0000000 0.4129423 0.3152202 0.2691612 0.2406239

# Relative effectiveness of quit aids at 4 weeks
SmkContAbst("varenicline", 4) / SmkContAbst("placebo", 4)
# 2.279061

# For 1000 four-week quits on placebo, how many twelve-week quits
1000 * (SmkContAbst("placebo", 12) / SmkContAbst("placebo", 4))
# 651.8131

} # }