title: Sample Size Estimation for Negative Binomial Regression Comparing Rates of Recurrent Events with Unequal Follow-Up Time.
abstract: A sample size formula is derived for negative binomial regression for the analysis of recurrent events, in which subjects can have unequal follow-up time. We obtain sharp lower and upper bounds on the required size, which is easy to compute. The upper bound is generally only slightly larger than the required size, and hence can be used to approximate the sample size. The lower and upper size bounds can be decomposed into two terms. The first term relies on the mean number of events in each group, and the second term depends on two factors that measure, respectively, the extent of between-subject variability in event rates, and follow-up time. Simulation studies are conducted to assess the performance of the proposed method. An application of our formulae to a multiple sclerosis trial is provided.
authors.affiliation: a GlaxoSmithKline , Research Triangle Park , North Carolina , USA.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Tang
mesh_terms: D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D000068876:Fingolimod Hydrochloride / Q000627:therapeutic use; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis / Q000628:therapy; D009716:Numerical Analysis, Computer-Assisted; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012008:Recurrence; D018401:Sample Size; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D000068876:Fingolimod Hydrochloride
keywords: Negative binomial; Overdispersion; Power and sample size; Quasi-Poisson regression; Recurrent events.