#' Rectal Indomethacin for Prevention of Post-ERCP Pancreatitis
#'
#' @description
#' Patient-level data from a multi-center, randomized, double-blind,
#' placebo-controlled 2-arm trial (n = 602) of rectal indomethacin (100 mg)
#' versus placebo to prevent post-ERCP pancreatitis in high-risk patients,
#' as reported by Elmunzer, Higgins, et al. (2012) in the
#' \emph{New England Journal of Medicine}.
#'
#' This dataset was originally collected, cleaned, reformatted, and released
#' for public teaching and research use by Dr. Peter D. R. Higgins in the
#' \pkg{medicaldata} R package as \code{indo_rct}. The version shipped here is
#' redistributed in support of the worked examples in this package. The
#' variable definitions below follow \pkg{medicaldata}; note that a few
#' columns are stored as numeric (rather than factor) in this copy. Users who
#' need the authoritative copy or accompanying documentation should consult
#' \pkg{medicaldata}.
#'
#' @name indo
#' @docType data
#' @format A data frame with 602 observations on the following 33 variables:
#' \describe{
#'   \item{\code{id}}{Subject identifier (numeric); leading digit indicates
#'     center. Range 1001--4003.}
#'   \item{\code{site}}{Study site (factor, 4 levels):
#'     \code{1_UM} = University of Michigan,
#'     \code{2_IU} = Indiana University,
#'     \code{3_UK} = University of Kentucky,
#'     \code{4_Case} = Case Western Reserve University.}
#'   \item{\code{age}}{Age in years (numeric), range 19--90.}
#'   \item{\code{risk}}{Risk score for post-ERCP pancreatitis (numeric),
#'     range 1--5.5.}
#'   \item{\code{gender}}{Sex (factor): \code{1_female}, \code{2_male}.}
#'   \item{\code{outcome}}{Primary outcome: post-ERCP pancreatitis
#'     (numeric, 1 = yes, 0 = no).}
#'   \item{\code{sod}}{Sphincter of Oddi dysfunction present (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{pep}}{History of prior post-ERCP pancreatitis (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{recpanc}}{History of recurrent pancreatitis (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{psphinc}}{Pancreatic sphincterotomy performed (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{precut}}{Sphincter pre-cut needed to enter papilla (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{difcan}}{Cannulation of papilla was difficult (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{pneudil}}{Pneumatic dilation of papilla performed (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{amp}}{Ampullectomy performed (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{paninj}}{Contrast injected into pancreas (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{acinar}}{Pancreas appeared to have acinarization on imaging
#'     (factor): \code{0_no}, \code{1_yes}.}
#'   \item{\code{brush}}{Brushings taken from pancreatic duct (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{asa81}}{Aspirin used at 81 mg per day (factor with 3 levels):
#'     \code{0_no}, \code{1_yes}, and a third level retained from the
#'     source coding.}
#'   \item{\code{asa325}}{Aspirin used at 325 mg per day (factor with 3
#'     levels): \code{0_no}, \code{1_yes}, and a third level retained from
#'     the source coding.}
#'   \item{\code{asa}}{Aspirin used at any dose (factor with 3 levels):
#'     \code{0_no}, \code{1_yes}, and a third level retained from the
#'     source coding.}
#'   \item{\code{prophystent}}{Pancreatic duct stent placed per endoscopist
#'     judgment (factor): \code{0_no}, \code{1_yes}.}
#'   \item{\code{therastent}}{Pancreatic duct stent placed to treat narrowing
#'     (factor): \code{0_no}, \code{1_yes}.}
#'   \item{\code{pdstent}}{Pancreatic duct stent placed for any reason
#'     (factor): \code{0_no}, \code{1_yes}.}
#'   \item{\code{sodsom}}{Sphincter of Oddi manometry performed (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{bsphinc}}{Biliary sphincterotomy performed (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{bstent}}{Biliary stent placed to relieve obstruction
#'     (factor): \code{0_no}, \code{1_yes}.}
#'   \item{\code{chole}}{Choledocholithiasis present (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{pbmal}}{Biliary duct or pancreatic malignancy found (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{train}}{Trainee participated in ERCP (factor):
#'     \code{0_no}, \code{1_yes}.}
#'   \item{\code{status}}{Patient status (factor):
#'     \code{0_inpatient}, \code{1_outpatient}.}
#'   \item{\code{type}}{Sphincter of Oddi dysfunction type (factor):
#'     \code{0_no SOD}, \code{1_type 1}, \code{2_type 2}, \code{3_type 3}.}
#'   \item{\code{rx}}{Treatment assignment (numeric, 1 = indomethacin,
#'     0 = placebo).}
#'   \item{\code{bleed}}{Reportable gastrointestinal bleeding (numeric,
#'     coded 1 = no, 2 = yes; \code{NA} when not assessed).}
#' }
#'
#' @source
#' Higgins, P. D. R. \pkg{medicaldata}: Data Package for Medical Datasets.
#' R package, dataset \code{indo_rct}.
#' \url{https://CRAN.R-project.org/package=medicaldata}
#'
#' @references
#' Elmunzer BJ, Higgins PDR, Saini SD, et al. A randomized trial of rectal
#' indomethacin to prevent post-ERCP pancreatitis.
#' \emph{New England Journal of Medicine} 2012; 366(15):1414--1422.
#' \doi{10.1056/NEJMoa1111103}
#'
#' @examples
#' data(indo)
#'
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