Analysis of rodent growth data in toxicology studies

To evaluate compound-related effects on the growth of rodents, body weight and food consumption data are commonly collected either weekly or biweekly in toxicology studies. Body weight gain, food consumption relative to body weight, and efficiency of food utilization can be derived from body weight and food consumption for each animal in an attempt to better understand the compound-related effects. These five parameters are commonly analyzed in toxicology studies for each sex using a one-factor analysis of variance (ANOVA) at each collection point. The objective of this manuscript is to present an alternative approach to the evaluation of compound-related effects on body weight and food consumption data from both subchronic and chronic rodent toxicology studies. This approach is to perform a repeated-measures ANOVA on a selected set of parameters and analysis intervals. Compared with a standard one-factor ANOVA, this approach uses a statistical analysis method that has greater power and reduces the number of false-positive claims, and consequently provides a succinct yet comprehensive summary of the compound-related effects. Data from a mouse carcinogenicity study are included to illustrate this repeated-measures ANOVA approach to analyzing growth data in contrast with the one-factor ANOVA approach.