Comparison of Analysis of Covariance and Analysis of Variance in Pharmacokinetic Similarity Studies

The aim of this study was to evaluate the impact of demographic covariates on pharmacokinetic (PK) similarity assessment. A total of 30 PK similarity studies were analyzed to compare the use of analysis of covariance (ANCOVA) and analysis of variance (ANOVA). Trial simulations were conducted to further compare the two statistical approaches by varying sample size and covariates. Our analyses showed that ANCOVA and ANOVA were generally comparable in establishing PK similarity between the two products in the PK similarity studies. However, ANCOVA was observed to produce narrower confidence intervals and thus demonstrate higher power, particularly when the sample size was small.