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Recruitment prediction for multicenter clinical trials based on a hierarchical Poisson–gamma model: Asymptotic analysis and improved intervals: Asymptotic analysis and improved intervals

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
<mark>Journal publication date</mark>30/06/2022
<mark>Journal</mark>Biometrics
Issue number2
Volume78
Number of pages13
Pages (from-to)636-648
Publication StatusPublished
Early online date18/02/21
<mark>Original language</mark>English

Abstract

We analyze predictions of future recruitment to a multicenter clinical trial based on a maximum-likelihood fitting of a commonly used hierarchical Poisson–gamma model for recruitments at individual centers. We consider the asymptotic accuracy of quantile predictions in the limit as the number of recruitment centers grows large and find that, in an important sense, the accuracy of the quantiles does not improve as the number of centers increases. When predicting the number of further recruits in an additional time period, the accuracy degrades as the ratio of the additional time to the census time increases, whereas when predicting the amount of additional time to recruit a further n+• patients, the accuracy degrades as the ratio of n+• to the number recruited up to the census period increases. Our analysis suggests an improved quantile predictor. Simulation studies verify that the predicted pattern holds for typical recruitment scenarios in clinical trials and verify the much improved coverage properties of prediction intervals obtained from our quantile predictor. In the process of extending the applicability of our methodology, we show that in terms of the accuracy of all integer moments it is always better to approximate the sum of independent gamma random variables by a single gamma random variable matched on the first two moments than by the moment-matched Gaussian available from the central limit theorem

Bibliographic note

This is the peer reviewed version of the following article: Rachael Mountain, Chris Sherlock (2021), Recruitment prediction for multicenter clinical trials based on a hierarchical Poisson–gamma model: Asymptotic analysis and improved intervals. BIOMETRIC METHODOLOGY. doi: 10.1111/biom.13447 which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/biom.13447 This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.