Measure the Length of the Longest Abstinent Period — measure_abstinence

Find the longest number of sequential visits in the pattern with negative UDS

Usage

measure_abstinence_period(use_pattern_binary, use_is = "+")

Arguments

use_pattern_binary: A character string showing the daily, by visit, or weekly substance use pattern for a single subject, recoded to binary use or abstinence indicators.
use_is: Which single character is used to mark positive UDS in the use pattern string? Defaults to "+".

Value

An integer measuring the longest number of sequential visits for which the subject was abstinent from the substance(s) of interest. If the subject's entire use pattern is missing, then this will be 0.

Details

The use pattern MUST be in binary code for this function to work. For use patterns coded in our default language (see the "dictionary" in the Details section for measure_retention), the binary form would have all "_" (missing by study protocol) visits replaced with "-" and all "o" (missing for non-compliance) and "*" (mixed positive and negative) visits replaced with "+". See the example below.

Examples

  pattern_char <- "__++++*o-------+--+-o-o-o+o+oooooo"
  
  # replace "_" with "-"
  pattern2_char <- recode_missing_visits(
    pattern_char,
    missing_is = "_",
    missing_becomes = "-"
  )
  # replace "o" with "+"
  pattern3_char <- recode_missing_visits(pattern2_char)
  # replace "*" with "+"
  pattern4_char <- recode_missing_visits(pattern3_char, missing_is = "*")
  
  measure_abstinence_period(pattern4_char)
#> [1] 7