arv {bp}R Documentation

Average Real Variability (ARV)

Description

Calculate the Average Real Variability (ARV) at various levels of granularity based on what is supplied (ID, VISIT, WAKE, and / or DATE). ARV is a measure of dispersion that takes into account the temporal structure of the data and relies on the sum of absolute differences in successive observations, unlike the successive variation (SV) which relies on the sum of squared differences.

Usage

arv(data, inc_date = FALSE, subj = NULL, bp_type = 0, add_groups = NULL)

Arguments

data

Required argument. Pre-processed dataframe containing SBP and DBP with optional ID, VISIT, WAKE, and DATE columns if available. Use process_data to properly format data.

inc_date

Optional argument. Default is FALSE. As ABPM data typically overlaps due to falling asleep on one date and waking up on another, the inc_date argument is typically kept as FALSE, but the function will work regardless. Setting inc_date = TRUE will include these dates as a grouping level.

subj

Optional argument. Allows the user to specify and subset specific subjects from the ID column of the supplied data set. The subj argument can be a single value or a vector of elements. The input type should be character, but the function will comply with integers so long as they are all present in the ID column of the data.

bp_type

Optional argument. Determines whether to calculate ARV for SBP values or DBP values. Default is 0 corresponding to output for both SBP & DBP. For both SBP and DBP ARV values use bp_type = 0, for SBP-only use bp_type = 1, and for DBP-only use bp_type = 2

add_groups

Optional argument. Allows the user to aggregate the data by an additional "group" to further refine the output. The supplied input must be a character vector with the strings corresponding to existing column names of the processed data input supplied. Capitalization of add_groups does not matter. Ex: add_groups = c("Time_of_Day")

Value

A tibble object with a row corresponding to each subject, or alternatively a row corresponding to each date, if inc_date = TRUE. The resulting tibble consists of:

References

Mena et al. (2005) A reliable index for the prognostic significance of blood pressure variability Journal of Hypertension 23(5).505-11, doi: 10.1097/01.hjh.0000160205.81652.5a.

Examples

# Load data
data(hypnos_data)
data(bp_jhs)

# Process hypnos_data
hypnos_proc <- process_data(hypnos_data, sbp = "SYST", dbp = "DIAST", bp_datetime = "date.time",
id = "id", wake = "wake", visit = "visit", hr = "hr", pp ="pp", map = "map", rpp = "rpp")
# Process bp_jhs data
jhs_proc <- process_data(bp_jhs, sbp = "Sys.mmHg.", dbp = "Dias.mmHg.", bp_datetime = "DateTime",
hr = "Pulse.bpm.")

# ARV Calculation
arv(hypnos_proc, add_groups = c("SBP_Category"))
arv(jhs_proc, inc_date = TRUE)

[Package bp version 1.0.1 Index]