ss_ni_ve {ssutil}R Documentation

Sample Size and Non-Inferiority Margin for Vaccine Efficacy Trials

Description

Computes the non-inferiority margin, number of events, and maximum hazard ratio (HR) to declare non-inferiority in vaccine efficacy (VE) trials, based on the approach described by Fleming et al. (2021).

Usage

ss_ni_ve(ve_lci, alpha = 0.025, power = 0.9, use70 = FALSE, preserve = 0.5)

Arguments

ve_lci

Numeric. Lower bound of the current vaccine's efficacy (e.g., 0.95 for 95% VE).

alpha

Numeric. Type I error rate (default = 0.025).

power

Numeric. Desired power for the test (default = 0.90).

use70

Logical. If TRUE, assumes at least 30% VE for the new vaccine (the 90–70 rule); otherwise, preserves a fixed fraction of the reference VE.

preserve

Numeric. Proportion of the current vaccine's efficacy to preserve under use70 = FALSE (default = 0.5).

Details

The method applies either the 95–95 rule or 90–70 rule, depending on whether a minimum VE of 30% is assumed (use70 = TRUE) or 50% of the current VE is preserved.

This implementation approximates Table 1 of the paper using exact binomial confidence intervals via binom.test and the nBinomial1Sample function from gsDesign.

Value

A named list with:

References

Fleming, T.R., Powers, J.H., & Huang, Y. (2021). The use of active controls and non-inferiority studies in evaluating COVID-19 vaccines. Clinical Trials, 18(3), 335–342. doi:10.1177/1740774520988244

Examples

ss_ni_ve(ve_lci = 0.95)


[Package ssutil version 1.0.0 Index]