extract_publications {cthist}

Takes a data frame of the type provided by clinicaltrials_gov_download() and returns a new data frame containing one row per publication of the publication type specified indexed on ClinicalTrials.gov for every version of the clinical trial record provided.

Description

This function does not connect to ClinicalTrials.gov, and only interprets data that has already been downloaded by expanding the nested JSON-encoded data in the references column provided by clinicaltrial_gov_version.

Usage

extract_publications(df, types = c("RESULT", "BACKGROUND", "DERIVED"))

Arguments

df

A data frame containing at least the following columns: nctid, version_number, total_versions, version_date, and references. The references column should contain a nested JSON-encoded table with three columns: pmid, type and citation. This data frame can be generated by the use of clinicaltrials_gov_download.

types

A list of types to be returned or a character string if only one type specified, e.g. "RESULT" or c("RESULT", "BACKGROUND"). Allowed types: "RESULT", "BACKGROUND", "DERIVED".

Value

A data frame with all the original columns, as well as an additional three columns: pmid, type and citation. The new data frame will have one row per publication.

Examples

hv <- clinicaltrials_gov_download("NCT00942747", latest=TRUE)
extract_publications(hv)