clinicaltrials_gov_download {cthist}

Mass-download registry entry historical versions from ClinicalTrials.gov

Description

This function will download all ClinicalTrials.gov registry records for the NCT numbers specified. Rather than transcribing NCT numbers by hand, it is recommended that you conduct a search for trials of interest using the ClinicalTrials.gov web front-end and download the result as a comma-separated value (CSV) file. The CSV can be read in to memory as a data frame and the ⁠NCT Number⁠ column can be passed directly to the function as the nctids argument.

Usage

clinicaltrials_gov_download(
  nctids,
  output_filename = NA,
  quiet = FALSE,
  earliest = FALSE,
  latest = FALSE
)

Arguments

nctids

A list of well-formed NCT numbers, e.g. c("NCT00942747", "NCT03281616").

output_filename

A character string for a filename into which the data frame will be written as a CSV, e.g. "historical_versions.csv". If no output filename is provided, the data frame of downloaded historical versions will be returned by the function as a data frame.

quiet

A boolean TRUE or FALSE. If TRUE, no messages will be printed during download. FALSE by default, messages printed for every version downloaded showing progress.

earliest

A boolean TRUE or FALSE. If TRUE, only the earliest version of the registry entry will be downloaded, if FALSE, all versions will be downloaded. FALSE by default. Can be combined with latest.

latest

A boolean TRUE or FALSE. If TRUE, only the latest version of the registry entry will be downloaded, if FALSE, all versions will be downloaded. FALSE by default. Can be combined with earliest.

Value

If an output filename is specified, on successful completion, this function returns TRUE and otherwise returns FALSE. If an output filename is not specified, on successful completion, this function returns a data frame containing the historical versions of the clinical trial that have been retrieved, and in case of error returns FALSE. After unsuccessful completion with an output filename specified, if the function is called again with the same NCT numbers and output filename, the function will check the output file for errors or incompletely downloaded registry entries, remove them and try to download the historical versions that are still needed, while preserving the ones that have already been downloaded correctly.

Examples

filename <- tempfile()
clinicaltrials_gov_download(c("NCT00942747",
    "NCT03281616"), filename)



hv <- clinicaltrials_gov_download("NCT00942747")